HRV-1A infection fragments the Golgi apparatus and redistributes Golgi membranes into vesicles approximately 250-500nm in diameter. These Golgi-derived vesicles colocalize with viral RNA replication templates, indicating they serve as sites of viral RNA replication. Expression of the HRV-1A 3A protein alone is sufficient to induce Golgi fragmentation similar to infection and the 3A protein localizes to the Golgi-derived membranes, suggesting it plays a role in Golgi fragmentation to generate membranes for viral replication.
This document summarizes a study examining the receptor(s) that mediate dendritic cell (DC) acquisition of antigen from live cells, a process known as "nibbling". The study found that scavenger receptors (SR), particularly class A SR (SR-A), play a role in DC nibbling. SR-A expression correlated with the ability to acquire membrane from live cells. Internalized membrane colocalized with SR ligands and entered the endosomal pathway. Cross-presentation of tumor antigen by DC to T cells was inhibited by polyanionic SR ligands and anti-SR-A antibody, suggesting SR-A mediates antigen acquisition from live cells by DC.
This document discusses a study that used proteomic techniques like SDS-PAGE and 2D electrophoresis to identify and characterize secreted proteins from Streptococcus pneumoniae bacteria. 236 proteins were found, located in the extracellular space (21), cell wall (4), or cell membrane (31). Some proteins identified, like ZmpB and Sphtra, are highly immunogenic and potential vaccine candidates. The study provides insights into S. pneumoniae pathogenic factors and membrane proteins that could contribute to pneumococcal disease. Identifying secreted proteins through immuno-proteomic analysis may help develop effective vaccines to reduce mortality from pneumonia.
Karyotype variability in plant pathogenic fungi palm7016chaithram11
This document summarizes a seminar presentation on karyotype variability in plant pathogenic fungi. It discusses types of karyotype variability including chromosome number polymorphisms and chromosome length polymorphisms. Mechanisms that can lead to karyotype variability are described, such as meiotic recombination, DNA repair pathways, parasexual recombination, transposon-associated rearrangements, and lateral DNA transfer. Case studies on fungi like Mycosphaerella graminicola and Alternaria alternata are provided that demonstrate karyotype changes through these mechanisms. The importance of karyotype variability in the evolution and emergence of new virulence strains in fungi is also noted.
1. The study aims to characterize the bacteriophage Samisiti12 that infects Streptomyces griseus through RNA sequencing at different time points during infection to identify genes expressed early and late in the phage lifecycle.
2. Samples of the phage-bacteria culture will be taken at 30, 60, and 120 minutes post-infection for RNA extraction, cDNA conversion, and sequencing.
3. It is hypothesized that sequences on the right arm of the phage genome will be expressed early to encode proteins for DNA synthesis and host immunity, while sequences on the left arm expressed late will encode structural proteins for virion construction.
The document discusses the genetic epidemiology of tuberculosis. It summarizes that analysis of TB epidemics in Europe from the 18th-19th centuries found mortality rates of up to 2% per year without chemotherapy. There was an initial spike in cases over the first 50-100 years, followed by a slow decline over the next 200-250 years. This supports the hypothesis that the initial phase eliminated the most susceptible 20% of the population.
This document proposes a hypothesis for the origin of the three cellular domains of life - Archaea, Bacteria, and Eukarya. It suggests that independent transfers of DNA viruses to existing RNA cells gave rise to the three domains. Each transfer stabilized a different version of the proteins involved in translation. The existence of three different founder DNA viruses also explains why each domain has distinct DNA replication machinery. This model aims to address weaknesses in other models and explain why informational proteins differ across domains.
Hammerhead ribozymes (hRzs) targeting two regions of the Chikungunya virus (CHIKv) genome were effective at inhibiting CHIKv replication and transmission in cell cultures and transgenic Aedes aegypti mosquitoes. hRz#9 and hRz#14 were the most potent inhibitors of CHIKv, preventing cytopathic effects in transformed Vero cells and blocking CHIKv transmission in the saliva of transgenic mosquitoes. While hRzs show promise as transgenic antiviral molecules for population replacement strategies, further analysis is needed using natural CHIKv strains and mosquito populations.
This document describes the construction and characterization of recombinant viruses containing the HIV-1 env gene from seminal strains. The researchers amplified the V1-V3 region of env from seminal plasma samples and used it to construct chimeric viruses by co-transfecting the V1-V3 fragment into a V1-V3 deleted vector. Four chimeric viruses were able to replicate and were characterized as using CXCR4 as a coreceptor. Confocal microscopy was used to observe the interaction of the cell-free viral particles with reporter cell lines. The recombinant viruses representing seminal strains are useful tools for studying heterosexual HIV transmission and testing microbicides.
This document summarizes a study examining the receptor(s) that mediate dendritic cell (DC) acquisition of antigen from live cells, a process known as "nibbling". The study found that scavenger receptors (SR), particularly class A SR (SR-A), play a role in DC nibbling. SR-A expression correlated with the ability to acquire membrane from live cells. Internalized membrane colocalized with SR ligands and entered the endosomal pathway. Cross-presentation of tumor antigen by DC to T cells was inhibited by polyanionic SR ligands and anti-SR-A antibody, suggesting SR-A mediates antigen acquisition from live cells by DC.
This document discusses a study that used proteomic techniques like SDS-PAGE and 2D electrophoresis to identify and characterize secreted proteins from Streptococcus pneumoniae bacteria. 236 proteins were found, located in the extracellular space (21), cell wall (4), or cell membrane (31). Some proteins identified, like ZmpB and Sphtra, are highly immunogenic and potential vaccine candidates. The study provides insights into S. pneumoniae pathogenic factors and membrane proteins that could contribute to pneumococcal disease. Identifying secreted proteins through immuno-proteomic analysis may help develop effective vaccines to reduce mortality from pneumonia.
Karyotype variability in plant pathogenic fungi palm7016chaithram11
This document summarizes a seminar presentation on karyotype variability in plant pathogenic fungi. It discusses types of karyotype variability including chromosome number polymorphisms and chromosome length polymorphisms. Mechanisms that can lead to karyotype variability are described, such as meiotic recombination, DNA repair pathways, parasexual recombination, transposon-associated rearrangements, and lateral DNA transfer. Case studies on fungi like Mycosphaerella graminicola and Alternaria alternata are provided that demonstrate karyotype changes through these mechanisms. The importance of karyotype variability in the evolution and emergence of new virulence strains in fungi is also noted.
1. The study aims to characterize the bacteriophage Samisiti12 that infects Streptomyces griseus through RNA sequencing at different time points during infection to identify genes expressed early and late in the phage lifecycle.
2. Samples of the phage-bacteria culture will be taken at 30, 60, and 120 minutes post-infection for RNA extraction, cDNA conversion, and sequencing.
3. It is hypothesized that sequences on the right arm of the phage genome will be expressed early to encode proteins for DNA synthesis and host immunity, while sequences on the left arm expressed late will encode structural proteins for virion construction.
The document discusses the genetic epidemiology of tuberculosis. It summarizes that analysis of TB epidemics in Europe from the 18th-19th centuries found mortality rates of up to 2% per year without chemotherapy. There was an initial spike in cases over the first 50-100 years, followed by a slow decline over the next 200-250 years. This supports the hypothesis that the initial phase eliminated the most susceptible 20% of the population.
This document proposes a hypothesis for the origin of the three cellular domains of life - Archaea, Bacteria, and Eukarya. It suggests that independent transfers of DNA viruses to existing RNA cells gave rise to the three domains. Each transfer stabilized a different version of the proteins involved in translation. The existence of three different founder DNA viruses also explains why each domain has distinct DNA replication machinery. This model aims to address weaknesses in other models and explain why informational proteins differ across domains.
Hammerhead ribozymes (hRzs) targeting two regions of the Chikungunya virus (CHIKv) genome were effective at inhibiting CHIKv replication and transmission in cell cultures and transgenic Aedes aegypti mosquitoes. hRz#9 and hRz#14 were the most potent inhibitors of CHIKv, preventing cytopathic effects in transformed Vero cells and blocking CHIKv transmission in the saliva of transgenic mosquitoes. While hRzs show promise as transgenic antiviral molecules for population replacement strategies, further analysis is needed using natural CHIKv strains and mosquito populations.
This document describes the construction and characterization of recombinant viruses containing the HIV-1 env gene from seminal strains. The researchers amplified the V1-V3 region of env from seminal plasma samples and used it to construct chimeric viruses by co-transfecting the V1-V3 fragment into a V1-V3 deleted vector. Four chimeric viruses were able to replicate and were characterized as using CXCR4 as a coreceptor. Confocal microscopy was used to observe the interaction of the cell-free viral particles with reporter cell lines. The recombinant viruses representing seminal strains are useful tools for studying heterosexual HIV transmission and testing microbicides.
1) Researchers studied the origin of the retrovirus XMRV, which has been detected in human prostate tumors and chronic fatigue syndrome patients.
2) They found two related murine endogenous retroviruses, PreXMRV-1 and PreXMRV-2, in the mouse strains used to passage the human CWR22 prostate tumor xenograft.
3) The researchers conclude that XMRV likely arose through recombination of PreXMRV-1 and PreXMRV-2 during passage of the CWR22 xenograft in mice, as the CWR22 tumor itself did not contain XMRV but later passages and cell lines derived from it did.
Two metagenomic datasets from a Brazilian lake impacted by cyanobacterial blooms were analyzed to explore the dominant cyanobacterial population. Over 99% of reads were assigned to Cylindrospermopsis and Raphidiopsis genera. The most abundant strains, Raphidiopsis brookii D9 and Cylindrospermopsis raciborskii CS505, shared over 99% nucleotide similarity but had some unique genes and gene clusters. Genomic regions with missing genes, high coverage, or low similarity alignments between the two strains were analyzed in more detail. The results suggest the presence of an unknown, closely related ecotype to R. brookii D9 and C. raciborskii T3
Yanli Li - Attachment and replication of genotype 1 porcine reproductive and ...John Blue
This study examined the attachment and replication of three genotype 1 PRRSV isolates (3249, 3262, 3267) on bone marrow-derived dendritic cells (BMDCs). The researchers derived immature and mature BMDCs from bone marrow cells and examined viral attachment at 4°C and replication at 37°C over 48 hours. They found that all three isolates attached to and replicated in both CD163+ and CD163- BMDCs, though replication was higher in immature BMDCs. Additionally, the isolates replicated at different rates depending on the activation status of the BMDCs. This suggests that while CD163 facilitates PRRSV infection, it may not be the sole receptor, and that B
El Gen Zombi que previene el cáncer en elefantesGabriel Conte
El informe científico en inglés: A zombie LIF gene in elephants is up-regulated by TP53 to induce apoptosis in response to DNA damage. En www.mdzol.com
This study investigated the role of the cellular protein annexin 2 (Anx2) in human immunodeficiency virus type 1 (HIV-1) particle production and infectivity. The researchers knocked down Anx2 expression by 98% in various cell types using lentiviruses encoding short hairpin RNAs against Anx2. They found that knocking down Anx2 did not reduce HIV-1 virus-like particle production in COS-1, 293T, Jurkat T cells, or primary human macrophages. Similarly, murine cells lacking Anx2 produced normal levels of particles. However, supernatants from Anx2-depleted primary human macrophages exhibited decreased infectivity, indicating Anx2 plays a
This document describes a study that sequenced the 23S rRNA gene of Campylobacter coli VC167 and analyzed its sequence and structure. It found that the gene contained a 147 bp transcribed spacer that resulted in fragmented 23S rRNA. Analysis of 31 other C. coli and C. jejuni strains found that 69% contained a transcribed spacer of 147 bp or 37 bp, also producing fragmented 23S rRNA. Phylogenetic analysis placed Campylobacter in the epsilon subdivision of Proteobacteria based on signatures in the 23S rRNA at positions 270 and 1850.
The genotoxic potential of the RqlH helicase is curbed by RqlI activity in ex...Colin Russell
This part of my PhD work was to figure out what a particular bacterial gene does. We knew that it was important for E. coli to cause disease, but we didn't understand how it did this. This presentation outlines how we figured out the role of this gene in E. coli.
Given to the Bacterial Ultra Group (BUG) of Singapore on 11 May 2017.
This document summarizes work to construct an infectious clone of the squirrel monkey strain of simian foamy virus (SFVsqu). The researchers amplified fragments of the SFVsqu genome using PCR and plan to fuse the fragments together using Gibson assembly to generate a full-length circular viral genome. This cloned genome can then be transfected into mammalian cells to produce virus particles and allow study of the viral lifecycle. The researchers acknowledge funding sources and cite relevant references. Construction of this infectious clone will enable future study of how the human immune system responds to infection with New World Monkey strains of SFV.
This document describes a study conducted at Los Alamos National Laboratory to investigate the evolution of influenza A virus (IAV) under artificial selection pressure. The researchers engineered host cells to express IAV proteins and infected these "supplemented" cells with IAV over multiple passages. They hypothesized that the virus would evolve to efficiently infect the supplemented cells while losing ability to infect unmodified cells. Preliminary results found measurable viral replication in supplemented cells expressing one IAV protein (PB1C1) over generations, but limited replication in cells expressing another protein (M1), suggesting it may interfere with virion packaging. The goal is to better understand viral evolution and identify novel antiviral strategies.
Capsular profiling of the Cronobacter genus and the association of specific C...Pauline Ogrodzki
This study analyzed capsule-associated gene clusters involved in polysaccharide production in 104 whole genome sequenced Cronobacter strains, covering all seven species. It identified 38 potential O-antigen serotypes based on phylogeny of the O-antigen flanking genes gnd and galF. Two variants of the colanic acid gene cluster and the presence of cellulose and ECA genes were observed. C. sakazakii and C. malonaticus isolates with the capsular type [K2:CA2:Cell+] were most associated with neonatal meningitis and necrotizing enterocolitis. The study proposes a new capsular typing scheme and identifies a possible virulence trait related to severe neonatal
Franz Zhang et al Weevil Workshop 2016 Neotropical Entiminae Systematics evol...taxonbytes
The document discusses research on the Neotropical Entiminae weevil subfamily, including a molecular phylogeny that showed the Exophthalmus genus complex is polyphyletic. Historical biogeography analysis found Caribbean island ancestry with jump dispersal between islands accounting for 25% of range evolution. Molecular profiling of gut contents identified host plant associations and multiple bacterial symbionts across weevil specimens using next-generation sequencing.
This document discusses macrophages in the intestine and their roles in homeostasis and inflammation. It begins by noting the challenges in identifying intestinal macrophages due to overlap with other myeloid cells. It then describes how macrophages can be identified in the intestine using multiple markers like CD64, F4/80, and CX3CR1. The document outlines the anatomical distribution of intestinal macrophages and their key functions in homeostasis like clearing apoptotic cells and regulating epithelial proliferation. It also notes macrophages are highly phagocytic and help maintain tolerance to commensal bacteria by not triggering inflammatory responses. Finally, it discusses how macrophages may change during inflammation.
Unraveling Virus Complexes in Plants/ CIAT APR 2015CIAT
This document summarizes the work of Wilmer J. Cuellar on unraveling virus complexes in plants. It discusses that viruses occur in complex communities and interact in various ways. Historically, plant viruses were described based on symptoms alone, but it is now understood that single strains grown in pure culture do not reflect reality. Viruses often occur as mixed infections in nature, and can have varying impacts depending on the plant variety infected. The document outlines research on complex virus infections in cassava and sweet potato. It emphasizes the importance of early identification and surveillance of potential virus threats. Improving diagnostic tools is key to evaluating cleaning protocols and detecting early infections. Understanding virus diversity and interactions is important for disease management.
This document discusses classification and viruses. It describes how phylogenies are based on homologous structures in living organisms that provide evidence of common ancestry. It also discusses how molecular biology is a powerful tool in systematics, allowing phylogenetic hypotheses to be developed based on molecular comparisons. Viruses can integrate their DNA into host cells and remain latent for long periods. Bacteria can also transfer genes through transformation, transduction, or conjugation.
Tumor viruses can infect cells through either a lytic or latent life cycle. In the latent cycle, the virus genome integrates into the host cell DNA and causes cellular transformation by interfering with normal cell growth control mechanisms. This transformation allows infected cells to proliferate unchecked and form tumors. There are two major classes of tumor viruses - DNA and RNA viruses. DNA tumor viruses like hepatitis B virus and human papillomavirus can contribute to cancers like hepatocellular carcinoma and cervical cancer. RNA tumor viruses are retroviruses that carry the enzyme reverse transcriptase and integrate their RNA genome into host cell DNA, possibly inserting oncogenes that drive transformation.
This document summarizes a study that used PCR and cloning to analyze the 16S rRNA genes present in a natural marine bacterioplankton population from the Sargasso Sea. Researchers constructed a library of 51 small-subunit rRNA genes and sequenced five unique genes. In addition to genes from known marine Synechococcus and SAR11 lineages, they identified two new classes of genes belonging to alpha- and gamma-proteobacteria, confirming that many planktonic bacteria have not been previously recognized by microbiologists.
1) Researchers sequenced the genome of "Coxiella-like endosymbiont of Amblyomma americanum" (CLEAA), a bacterium that lives within the lone star tick.
2) Analysis of the CLEAA genome revealed it contains pathways for biosynthesis of many vitamins and cofactors that are scarce in vertebrate blood. This suggests CLEAA plays a role in providing nutrients to the tick.
3) CLEAA is highly prevalent within the lone star tick and is closely related to Coxiella burnetii, the agent of Q fever, but does not appear to be directly derived from it. In contrast to C. burnetii, CLE
UC Davis EVE161 Lecture 14 by @phylogenomicsJonathan Eisen
This document contains slides from a lecture on metagenomics and microbial phylogenomics. The lecture discusses the history and development of metagenomics, which involves studying the collective genomes of microbes in an environment. It reviews key papers on metagenomics and the discovery of proteorhodopsin and the SAR11 lineage of bacteria from environmental samples. The slides also discuss previous findings on marine microbes from rRNA studies and introduce two new lineages of alpha- and gamma-proteobacteria identified from an analysis of 16S rRNA genes cloned from Sargasso Sea bacterioplankton DNA.
This document discusses rhabdoviruses like rabies virus and reoviruses like rotavirus. It provides information on their structure, replication cycles, pathogenesis, epidemiology, clinical manifestations, diagnosis and treatment/prevention. Rhabdoviruses have a negative-sense RNA genome and cause diseases like rabies through bites. Rotaviruses are the most common cause of severe diarrhea in infants worldwide and have a double-layered capsid enclosing 11 segments of double-stranded RNA.
Evolutionary origins of the SARS-CoV-2 sarbecovirus lineage responsible for t...Guy Boulianne
This document analyzes the evolutionary history of SARS-CoV-2, the virus that causes COVID-19, using genomic data from related sarbecoviruses found in bats. The key points are:
- Sarbecoviruses undergo frequent recombination, exhibiting spatially structured genetic diversity in China. SARS-CoV-2 itself shows no evidence of being a recombinant of known sarbecoviruses.
- Bayesian analyses estimate the most recent common ancestor of SARS-CoV-2 and its closest known relative, RaTG13, existed between 1948-2009, indicating the lineage has been circulating unnoticed in bats for decades.
- While pangolins or other species may have facilitated transmission to
1) Researchers studied the origin of the retrovirus XMRV, which has been detected in human prostate tumors and chronic fatigue syndrome patients.
2) They found two related murine endogenous retroviruses, PreXMRV-1 and PreXMRV-2, in the mouse strains used to passage the human CWR22 prostate tumor xenograft.
3) The researchers conclude that XMRV likely arose through recombination of PreXMRV-1 and PreXMRV-2 during passage of the CWR22 xenograft in mice, as the CWR22 tumor itself did not contain XMRV but later passages and cell lines derived from it did.
Two metagenomic datasets from a Brazilian lake impacted by cyanobacterial blooms were analyzed to explore the dominant cyanobacterial population. Over 99% of reads were assigned to Cylindrospermopsis and Raphidiopsis genera. The most abundant strains, Raphidiopsis brookii D9 and Cylindrospermopsis raciborskii CS505, shared over 99% nucleotide similarity but had some unique genes and gene clusters. Genomic regions with missing genes, high coverage, or low similarity alignments between the two strains were analyzed in more detail. The results suggest the presence of an unknown, closely related ecotype to R. brookii D9 and C. raciborskii T3
Yanli Li - Attachment and replication of genotype 1 porcine reproductive and ...John Blue
This study examined the attachment and replication of three genotype 1 PRRSV isolates (3249, 3262, 3267) on bone marrow-derived dendritic cells (BMDCs). The researchers derived immature and mature BMDCs from bone marrow cells and examined viral attachment at 4°C and replication at 37°C over 48 hours. They found that all three isolates attached to and replicated in both CD163+ and CD163- BMDCs, though replication was higher in immature BMDCs. Additionally, the isolates replicated at different rates depending on the activation status of the BMDCs. This suggests that while CD163 facilitates PRRSV infection, it may not be the sole receptor, and that B
El Gen Zombi que previene el cáncer en elefantesGabriel Conte
El informe científico en inglés: A zombie LIF gene in elephants is up-regulated by TP53 to induce apoptosis in response to DNA damage. En www.mdzol.com
This study investigated the role of the cellular protein annexin 2 (Anx2) in human immunodeficiency virus type 1 (HIV-1) particle production and infectivity. The researchers knocked down Anx2 expression by 98% in various cell types using lentiviruses encoding short hairpin RNAs against Anx2. They found that knocking down Anx2 did not reduce HIV-1 virus-like particle production in COS-1, 293T, Jurkat T cells, or primary human macrophages. Similarly, murine cells lacking Anx2 produced normal levels of particles. However, supernatants from Anx2-depleted primary human macrophages exhibited decreased infectivity, indicating Anx2 plays a
This document describes a study that sequenced the 23S rRNA gene of Campylobacter coli VC167 and analyzed its sequence and structure. It found that the gene contained a 147 bp transcribed spacer that resulted in fragmented 23S rRNA. Analysis of 31 other C. coli and C. jejuni strains found that 69% contained a transcribed spacer of 147 bp or 37 bp, also producing fragmented 23S rRNA. Phylogenetic analysis placed Campylobacter in the epsilon subdivision of Proteobacteria based on signatures in the 23S rRNA at positions 270 and 1850.
The genotoxic potential of the RqlH helicase is curbed by RqlI activity in ex...Colin Russell
This part of my PhD work was to figure out what a particular bacterial gene does. We knew that it was important for E. coli to cause disease, but we didn't understand how it did this. This presentation outlines how we figured out the role of this gene in E. coli.
Given to the Bacterial Ultra Group (BUG) of Singapore on 11 May 2017.
This document summarizes work to construct an infectious clone of the squirrel monkey strain of simian foamy virus (SFVsqu). The researchers amplified fragments of the SFVsqu genome using PCR and plan to fuse the fragments together using Gibson assembly to generate a full-length circular viral genome. This cloned genome can then be transfected into mammalian cells to produce virus particles and allow study of the viral lifecycle. The researchers acknowledge funding sources and cite relevant references. Construction of this infectious clone will enable future study of how the human immune system responds to infection with New World Monkey strains of SFV.
This document describes a study conducted at Los Alamos National Laboratory to investigate the evolution of influenza A virus (IAV) under artificial selection pressure. The researchers engineered host cells to express IAV proteins and infected these "supplemented" cells with IAV over multiple passages. They hypothesized that the virus would evolve to efficiently infect the supplemented cells while losing ability to infect unmodified cells. Preliminary results found measurable viral replication in supplemented cells expressing one IAV protein (PB1C1) over generations, but limited replication in cells expressing another protein (M1), suggesting it may interfere with virion packaging. The goal is to better understand viral evolution and identify novel antiviral strategies.
Capsular profiling of the Cronobacter genus and the association of specific C...Pauline Ogrodzki
This study analyzed capsule-associated gene clusters involved in polysaccharide production in 104 whole genome sequenced Cronobacter strains, covering all seven species. It identified 38 potential O-antigen serotypes based on phylogeny of the O-antigen flanking genes gnd and galF. Two variants of the colanic acid gene cluster and the presence of cellulose and ECA genes were observed. C. sakazakii and C. malonaticus isolates with the capsular type [K2:CA2:Cell+] were most associated with neonatal meningitis and necrotizing enterocolitis. The study proposes a new capsular typing scheme and identifies a possible virulence trait related to severe neonatal
Franz Zhang et al Weevil Workshop 2016 Neotropical Entiminae Systematics evol...taxonbytes
The document discusses research on the Neotropical Entiminae weevil subfamily, including a molecular phylogeny that showed the Exophthalmus genus complex is polyphyletic. Historical biogeography analysis found Caribbean island ancestry with jump dispersal between islands accounting for 25% of range evolution. Molecular profiling of gut contents identified host plant associations and multiple bacterial symbionts across weevil specimens using next-generation sequencing.
This document discusses macrophages in the intestine and their roles in homeostasis and inflammation. It begins by noting the challenges in identifying intestinal macrophages due to overlap with other myeloid cells. It then describes how macrophages can be identified in the intestine using multiple markers like CD64, F4/80, and CX3CR1. The document outlines the anatomical distribution of intestinal macrophages and their key functions in homeostasis like clearing apoptotic cells and regulating epithelial proliferation. It also notes macrophages are highly phagocytic and help maintain tolerance to commensal bacteria by not triggering inflammatory responses. Finally, it discusses how macrophages may change during inflammation.
Unraveling Virus Complexes in Plants/ CIAT APR 2015CIAT
This document summarizes the work of Wilmer J. Cuellar on unraveling virus complexes in plants. It discusses that viruses occur in complex communities and interact in various ways. Historically, plant viruses were described based on symptoms alone, but it is now understood that single strains grown in pure culture do not reflect reality. Viruses often occur as mixed infections in nature, and can have varying impacts depending on the plant variety infected. The document outlines research on complex virus infections in cassava and sweet potato. It emphasizes the importance of early identification and surveillance of potential virus threats. Improving diagnostic tools is key to evaluating cleaning protocols and detecting early infections. Understanding virus diversity and interactions is important for disease management.
This document discusses classification and viruses. It describes how phylogenies are based on homologous structures in living organisms that provide evidence of common ancestry. It also discusses how molecular biology is a powerful tool in systematics, allowing phylogenetic hypotheses to be developed based on molecular comparisons. Viruses can integrate their DNA into host cells and remain latent for long periods. Bacteria can also transfer genes through transformation, transduction, or conjugation.
Tumor viruses can infect cells through either a lytic or latent life cycle. In the latent cycle, the virus genome integrates into the host cell DNA and causes cellular transformation by interfering with normal cell growth control mechanisms. This transformation allows infected cells to proliferate unchecked and form tumors. There are two major classes of tumor viruses - DNA and RNA viruses. DNA tumor viruses like hepatitis B virus and human papillomavirus can contribute to cancers like hepatocellular carcinoma and cervical cancer. RNA tumor viruses are retroviruses that carry the enzyme reverse transcriptase and integrate their RNA genome into host cell DNA, possibly inserting oncogenes that drive transformation.
This document summarizes a study that used PCR and cloning to analyze the 16S rRNA genes present in a natural marine bacterioplankton population from the Sargasso Sea. Researchers constructed a library of 51 small-subunit rRNA genes and sequenced five unique genes. In addition to genes from known marine Synechococcus and SAR11 lineages, they identified two new classes of genes belonging to alpha- and gamma-proteobacteria, confirming that many planktonic bacteria have not been previously recognized by microbiologists.
1) Researchers sequenced the genome of "Coxiella-like endosymbiont of Amblyomma americanum" (CLEAA), a bacterium that lives within the lone star tick.
2) Analysis of the CLEAA genome revealed it contains pathways for biosynthesis of many vitamins and cofactors that are scarce in vertebrate blood. This suggests CLEAA plays a role in providing nutrients to the tick.
3) CLEAA is highly prevalent within the lone star tick and is closely related to Coxiella burnetii, the agent of Q fever, but does not appear to be directly derived from it. In contrast to C. burnetii, CLE
UC Davis EVE161 Lecture 14 by @phylogenomicsJonathan Eisen
This document contains slides from a lecture on metagenomics and microbial phylogenomics. The lecture discusses the history and development of metagenomics, which involves studying the collective genomes of microbes in an environment. It reviews key papers on metagenomics and the discovery of proteorhodopsin and the SAR11 lineage of bacteria from environmental samples. The slides also discuss previous findings on marine microbes from rRNA studies and introduce two new lineages of alpha- and gamma-proteobacteria identified from an analysis of 16S rRNA genes cloned from Sargasso Sea bacterioplankton DNA.
This document discusses rhabdoviruses like rabies virus and reoviruses like rotavirus. It provides information on their structure, replication cycles, pathogenesis, epidemiology, clinical manifestations, diagnosis and treatment/prevention. Rhabdoviruses have a negative-sense RNA genome and cause diseases like rabies through bites. Rotaviruses are the most common cause of severe diarrhea in infants worldwide and have a double-layered capsid enclosing 11 segments of double-stranded RNA.
Evolutionary origins of the SARS-CoV-2 sarbecovirus lineage responsible for t...Guy Boulianne
This document analyzes the evolutionary history of SARS-CoV-2, the virus that causes COVID-19, using genomic data from related sarbecoviruses found in bats. The key points are:
- Sarbecoviruses undergo frequent recombination, exhibiting spatially structured genetic diversity in China. SARS-CoV-2 itself shows no evidence of being a recombinant of known sarbecoviruses.
- Bayesian analyses estimate the most recent common ancestor of SARS-CoV-2 and its closest known relative, RaTG13, existed between 1948-2009, indicating the lineage has been circulating unnoticed in bats for decades.
- While pangolins or other species may have facilitated transmission to
This document discusses the structure and evolution of viruses. It begins by describing the basic nucleic acid structure of viruses, which can be single or double stranded DNA or RNA surrounded by a protein capsid. It then covers Baltimore classification of viruses based on their mRNA synthesis and RNA genome sizes. The potential for rapid evolution in RNA viruses is examined, including quasispecies and recombination. Specific examples of evolution are provided for measles virus, myxoma virus, and influenza virus, which undergoes both antigenic drift and shifts.
potassium, chloride, bicarbonate, blood urea nitrogen (BUN), magnesium, creatinine, glucose, and sometimes calcium. Tests that focus on cholesterol levels can determine LDL and HDL cholesterol levels, as well as triglyceride levels.[6]
molecular mechanism of viral diseases and biotechnological interventions for ...wani amir
This document provides a summary of a seminar on molecular mechanisms of viral diseases and biotechnological interventions for major plant viral diseases. It discusses how viruses are structured and replicate within host cells, the types of plant virus genomes and modes of transmission. It also summarizes several major plant viruses and the symptoms they cause. The document outlines plant responses to viral infections, including various resistance mechanisms. It concludes by describing different transgenic technologies used to develop virus-resistant crops, such as using coat proteins, replicases, movement proteins, and RNA interference to induce pathogen-derived resistance.
Viruses infect all known species and can be classified in several ways, including by their genome, host range, and morphology. They require a living host cell to replicate and are made up of either DNA or RNA. The virus life cycle involves attachment to and entry into a host cell, uncoating of the viral genome, replication of the genome, assembly of new viral particles, and release of progeny virus. Viruses evolve through mutation and recombination, and new strains can emerge which infect new host species. The immune system provides protection against viruses through antibodies and T cells.
With brief acknowledgment overview for Pandemic viral infections
#Pharmaceutical
#Medical
#Viral Infection
1.)Introduction
2.) Assessment
(a) Stages
3.) Management
(a.) Containment
(b.) Mitigation
4.) Viral Infection Process
5.) Concerning diseases
6.) List of Antiviral Drugs
7.) Types of viral Infection
8.) Virus Structure
9.) Modification
10.) Causative Agent
10.) Geographical Modification
11.) References
A pandemic is defined as “an epidemic occuring worldwide, or over a very wide area, crossing international boundaries and usually affecting a large number of people”. The classical definition includes nothing about population immunity, virology, or disease severity.
This document summarizes a thesis project aimed at characterizing and developing tools to study the UL133/8 locus of human cytomegalovirus (HCMV). The UL133/8 locus encodes four viral proteins - UL133, UL135, UL136, and UL138 - that are thought to regulate HCMV latency and reactivation. The project cloned the genes for these four proteins and expressed them recombinantly in E. coli to enable future studies using small molecule modulators to probe protein function and interactions. This work provides a foundation for elucidating the mechanism by which these viral proteins control HCMV latency and reactivation, with implications for developing new antiviral therapies.
This document provides information about COVID-19, including its definition, epidemiology, etiology, structure, pathophysiology, transmission, symptoms, testing, treatment research, and vaccine research. It defines COVID-19 as a respiratory illness caused by a newly discovered coronavirus. It discusses the outbreak originating in Wuhan, China and the global spread of the disease. It also summarizes the virus's structure and life cycle within the body.
This grant proposal aims to analyze protein-protein interactions within the type-III secretion system (T3SS) of the pathogenic bacterium Chromobacterium violaceum. The researchers will use molecular techniques like PCR and the yeast two-hybrid system to study interactions between 11 proteins that are thought to be involved in Cpi-2, one of two T3SSs found in C. violaceum. Understanding these interactions could help identify new drug targets and vaccine components to treat infections caused by this antibiotic-resistant bacterium. The proposal outlines experiments to clone the genes of interest, test protein interactions using yeast two-hybrid screens, and build an interaction map of the Cpi-2 T3SS apparatus.
The potato virus X (PVX) is a plant RNA virus with a positive-sense single stranded RNA genome. Upon host cell infection, the viral replicase synthesizes minus-strand RNA from the genomic RNA to produce more genomic and subgenomic RNAs. These are translated to produce movement and coat proteins for cell-to-cell movement and virion encapsidation. PVX has a non-enveloped icosahedral structure and its genome contains 5 open reading frames encoding a replicase and proteins involved in cell-to-cell movement and virion formation.
Poliovirus is the causative agent of polio. It is a positive-sense RNA virus with an icosahedral capsid. There are three serotypes that infect humans via the fecal-oral route. While most infections are asymptomatic, in rare cases the virus enters the central nervous system and can cause paralysis or death. The virus evades the immune system by surviving the acidic stomach and replicating quickly before an immune response occurs. Vaccines provide immunity by generating antibodies that block viral replication and spread.
This document summarizes a seminar presentation on astrovirus. Astrovirus are non-enveloped, single-stranded RNA viruses that cause mild gastroenteritis. They have a star-shaped capsid and infect both mammals and birds. Astrovirus infection is diagnosed using RT-PCR or ELISA techniques. Symptoms include diarrhea, nausea, and abdominal pain. Prevention involves proper handwashing, food safety, and sanitation. The presentation covered the epidemiology, structure, replication cycle, pathogenesis, diagnosis, and prevention of astrovirus.
Covid-19 is caused by the SARS-CoV-2 virus. It was first identified in Wuhan, China in December 2019 and has since spread globally in a pandemic. Symptoms can range from mild to severe and include loss of taste/smell, breathing difficulties, fever and cough. Testing methods include RT-PCR. Coronaviruses are spherical with spikes and a lipid bilayer. They have a large RNA genome and replicate by translating their genome inside host cells and assembling new virus particles which are then released.
Retroviruses like HIV possess the enzyme reverse transcriptase which allows the viral RNA genome to be transcribed into DNA and integrated into the host cell genome. HIV specifically infects CD4+ T cells, macrophages, and dendritic cells, hijacking their machinery to replicate. Over time, HIV destroys increasingly more of the immune system by killing infected cells, until opportunistic infections or cancers can take hold, defining the acquired immunodeficiency syndrome (AIDS) stage of the infection.
This study investigated an outbreak of neonatal sepsis in a neonatal intensive care unit attributed to coagulase-negative staphylococci (CoNS). The aims were to assess the association between intravenous catheters and CoNS sepsis, identify persistent CoNS strains, and determine antibiotic resistance patterns. Random amplified polymorphic DNA (RAPD) analysis identified two main clusters of CoNS isolates, with some strains showing similarity over 88%, suggesting persistence. Staphylococcus capitis was the most prevalent pathogen, infecting 80% of patients and showing multi-drug resistance. The results support that CoNS are a significant cause of neonatal intensive care unit sepsis, can infect via intravenous catheters, and persistent strains may cir
This document summarizes theories on the origin and evolution of viruses. It discusses that viruses likely arose very early in the evolution of life on Earth and may have evolved from primitive RNA replicons. Viruses can emerge through mechanisms like mutation, recombination, and reassortment involving both cellular and viral genetic material. RNA viruses in particular evolve extremely rapidly due to high mutation rates, though some viruses can exhibit periods of evolutionary stasis. Selection plays a key role in driving virus evolution.
Viruses were first discovered in the late 1880s through experiments with tobacco mosaic virus. Since then, many other viruses have been discovered that infect plants, animals and bacteria. Viruses are generally too small to be seen with a light microscope and have a variety of structures depending on their nucleic acid content and presence of an envelope. They replicate by infiltrating a host cell and using the cell's machinery to produce more viral particles. There is ongoing debate about whether viruses are considered living organisms.
Viruses were first discovered in the late 1880s through experiments with tobacco mosaic virus. Since then, many other viruses have been discovered that infect plants, animals and bacteria. Viruses are generally too small to be seen with a light microscope and have a variety of structures depending on their nucleic acid content and presence of an envelope. They replicate by infiltrating a host cell and using the cell's machinery to produce more viral particles. There is ongoing debate about whether viruses are considered living organisms.
2. Rhinoviruses are, like poliovirus, a part of the Enterovirus genus, and
represent a large and diverse collection of at least 138 viruses, most of
which have only recently been sequenced (Palmenberg et al., 2009).
Human rhinoviruses are classified into major group viruses, which use
the ICAM-1 receptor for cell entry, and minor group viruses, which
enter cells by binding the low-density lipoprotein receptor (Uncapher
et al., 1991). They have been further classified into HRV-A, HRV-B, and
HRV-C groupings, the first two of which were originally determined by
their resistance to distinct classes of antiviral compounds (Andries
et al., 1990). The HRV-C group was more recently identified using viral
genomic array technology, and all three groupings have been verified
and refined by modern sequence analysis (Kistler et al., 2007;
Palmenberg et al., 2009).
Complete cDNA clones are available for producing several rhino-
viruses, including the HRV-1A, HRV-2, and HRV-14 strains (Callahan
et al., 1985; Duechler et al., 1989). The availability of these clones
allows production of isogenic stocks of virus; otherwise, repeated virus
passaging allows genomic drift to occur due to the low fidelity of the
RNA-dependent RNA polymerase (Wells et al., 2001). Close study of
such a large and closely related group of viruses will reveal both
differences and commonalities in generating replication membranes.
Here we investigate the origin of replication membranes for one of
the cloned rhinoviruses, HRV-1A, a minor group, HRV-A type virus.
We show that, unlike poliovirus, HRV-1A does not induce or respond
to the autophagic pathway. In addition, we provide evidence that
during HRV-1A infection, the Golgi is fragmented into vesicles that
appear to be used as a substrate for viral RNA replication. Finally, we
show that expression of the HRV-1A 3A protein induces changes in
Golgi staining reminiscent of the changes during HRV-1A infection,
and that the 3A protein co-localizes with the fragmented Golgi signal.
These data, taken together, indicate that HRV-1A uses the Golgi
apparatus as a source of RNA replication vesicles.
Results
Rhinovirus and autophagy
In previous work, we showed that poliovirus and two strains of
rhinovirus induce the formation of autophagosome-like vesicles
during infection, the cytoplasmic faces of which are used as a substrate
for viral RNA replication (Jackson et al., 2005). Here we extend our
studies on viruses and autophagy to another cloned rhinovirus strain,
HRV-1A. Background levels of autophagy vary from cell line to cell line,
so for these assays we used 293T human embryonic kidney cells, which
have a low background level of autophagy (Tanida et al., 2005). The
best marker for autophagosome formation is the microtubule-
associated light chain 3 (MAP-LC3, also known as hATG8 or LC3)
protein, which is required for generating nascent autophagic mem-
branes (Klionsky et al., 2008). As autophagic signaling is induced,
cellular pools of LC3 become lipidated and associated with autophago-
some membranes. Cytoplasmic GFP-LC3 indicates low levels of
autophagy, while punctate LC3 signal indicates increased membrane
association of LC3 on autophagosomes (Klionsky et al., 2008).
To examine induction of autophagosomes, 293T cells were
transfected with a plasmid expressing a GFP-LC3 fusion protein
(Jackson et al., 2005). Two days after transfection, cells were infected
with virus at an MOI of 50, mock infected, or treated with rapamycin to
induce autophagy. For each condition, three replicate samples of at
least 100 transfected cells each were counted under double-blinded
conditions. LC3 signal was scored as punctate or non-punctate. Some
representative images are depicted in Fig. 1A. Double-blinded
quantitation of these images, in which cells were scored as punctate
or non-punctate, is shown in Fig. 1B. The mock-infected cells
demonstrated low, intrinsic levels of LC3 puncta, and HRV-1A-infected
cells have equivalent levels. However, in PV-infected and rapamycin-
treated cells, approximately half of the population displayed LC3
puncta, an increase in puncta formation similar to that seen previously
for PV (Taylor et al., 2009). In addition, we have also found that HRV-
1A yield does not vary upon stimulation or inhibition of autophagy
(data not shown). These data indicate that the autophagic pathway is
not induced or subverted by HRV-1A infection.
Organelle staining in HRV-1A-infected cells
Since we did not observe autophagic induction during HRV-1A
infection, we wanted to observe cellular organelle markers for
potential changes during HRV-1A infection. WI-38 embryonic lung
fibroblasts have an ideal morphology for immunofluorescence
analysis and are one of the few cell lines that can be infected by all
rhinoviruses (Dolan et al., 1968). A single-cycle poliovirus or
rhinovirus infection in WI-38 cells proceeds for 48–56 h before the
cytopathic effect is observed (Fenters et al., 1967) a time course of
infection that we have confirmed. Therefore, we fixed cells 24 h post-
infection to visualize morphological changes at the mid-point of the
viral life cycle. Virus stocks were assessed by TCID50 assay in WI-38
cells, and infections were performed at matched TCID50.
First we tested the endoplasmic reticulum (ER) (Fig. 2, top). We
stained infected cells with Protein Disulfide Isomerase (PDI) to
observe the relative morphology of the ER. The characteristic lace-
like pattern of the ER can be seen, with denser regions near the
nucleus. This ER pattern, seen in mock-infected cells, is
B
MOCK
HRV-1ARAPA
A
*
*
*
*
HRV-1A
Mock
Rapamycin
PV
0
% punctate cells
PV
10 20 30 40 50 60
Fig. 1. Poliovirus, HRV-1A, and autophagy. (A) Representative images of punctate and
non-punctate GFP-LC3 localization from infected, mock-infected, and rapamycin-
treated cells. (B) Quantitation of autophagic induction. Cells transfected with GFP-LC3
were infected at an MOI of 50, treated with rapamycin, or mock treated for 6 h, then
fixed. A minimum of 100 cells were scored for punctate or cytoplasmic LC3 staining. The
percentage of punctate cells is shown. Asterisks indicate comparison of two conditions
by Student's t-test in which pb0.05.
186 C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
3. indistinguishable from that observed in infected cells. Next, we
stained infected cells with the live stain MitoTracker to observe
potential changes in the distribution or structure of the mitochondria.
We observe a typical reticulotubular pattern of mitochondrial
staining, and there were no significant changes in the staining pattern
between infected and uninfected cells (Fig. 2, second row).
Next we analyzed the Golgi apparatus. Infected and fixed cells were
stained for the Golgi cisternae marker Giantin (Fig. 2). The continuous
cisternae of the Golgi are clearly visible in a perianuclear region of
mock-infected cells. This typical pattern was not visible in the majority
of HRV-1A-infected cells. Instead, the Giantin staining in these cells is
disjointed and fragmented, with puncta and small oval-shaped
structures spread throughout the cell. To confirm that this effect was
related to infection, we co-stained for Giantin (red) and an antibody to
detect the HRV-1A capsid (green). While capsid protein is not present
in replication complexes, the presence of capsid in a cell indicates viral
entry. Mock-infected cells did not stain with capsid antibody, and the
Golgi appeared normal (Fig. 2, bottom row). All cells in the infected
population stained with capsid antibody, and in these cells Giantin
signal was abnormal, often appearing as punctae throughout the
cytoplasm. These fluorescent images were overlaid on DIC images of
the cells to show the perinuclear location of the Golgi signal.
To better observe the development of these unusual patterns of
Giantin staining, we performed a time course of infection (Fig. 3). At
6 h post-infection with HRV-1A, Golgi staining appears only slightly
more compacted than those in matched PV or mock infections. By 12 h
post-infection, the Golgi complex is more fragmented and spread
throughout the infected cell. This pattern continues until 24 h, when
the Giantin signal is distributed around the cell and fragmented into
puncta and small oval structures, with few reticular networks visible.
At 24 h post-infection with PV, we still identify a complex network of
continuous Golgi staining comparable to uninfected cells. These data
indicate that HRV-1A infection induces significant morphological
changes in the Golgi complex.
Since airway epithelial cells are the primary sites of HRV infection
in vivo, we wanted to determine if Golgi staining patterns were altered
in an airway epithelial-derived cell line (Lopez-Souza et al., 2009).
BEAS-2B lung epithelial cells were infected with HRV-1A (Fig. 4). At
24 h and 72 h post-infection, cells were fixed and stained for both
Giantin and a second Golgi marker, GM130, to ensure that the
redistribution of signal was not specific to Giantin. At 24 h.p.i., we
observed a redistribution of both Golgi markers. GM130 and Giantin
are found throughout the cytoplasm of uninfected cells but are
restricted to a small juxtanuclear region of HRV-1A-infected BEAS-2B
cells. This staining pattern is identical at 48 h.p.i. (data not shown). At
72 h.p.i. it is difficult to identify Golgi markers in any organized
pattern, and staining is punctate and spread throughout the
cytoplasm (Fig. 4). HRV-1A-infected BEAS-2B cells begin to round
up and lyse between 72 h and 84 h post-infection. At each observed
time point, both GM130 and Giantin re-localized, indicating that the
redistribution likely represents Golgi membrane redistribution, rather
than movement of a single marker to a different cellular location.
Sites of HRV-1A genome replication
Since the Giantin staining pattern was altered during HRV-1A
infection, we wanted to determine if the site of viral RNA replication
followed a similar pattern. To detect the sites of active RNA
replication, we synthesized fluorescent-labeled positive-sense RNA
probes in vitro. These probes hybridize to the negative-sense RNA
intermediate that is synthesized as a template for genomic synthesis
(Teterina et al., 2001). Our attempts at co-staining with antibody and
riboprobes destroyed RNA signal, presumably due to RNAses in the
antibody preparations, so the Giantin antibody was not used for this
experiment. Instead, WI-38 cells were first treated with the “Golgi
Organelle Lights RFP” reagent (Invitrogen), which allows visualization
of the Golgi stacks (Tan et al., 2009). This reagent expresses RFP fused
to the Golgi resident protein N-acetylgalactosaminyltransferase-2.
48 h after treatment with Organelle Lights, cells were infected
with HRV-1A for 24 h (Fig. 5A–F) or mock infected (G–I). Samples
were fixed and RNA probes were hybridized to cells in situ. Cells were
then imaged for the Golgi marker and either HRV-1A RNA (B, H) or
poliovirus RNA (E). Mock-infected cells (G–I) display intact Golgi with
clearly defined continuous patterns of staining, and background levels
of RNA hybridization. HRV-1A-infected cells (A–F) show a fragmented
juxtanuclear Organelle Lights Golgi signal. This signal co-localizes
with a positive-sense HRV-1A genomic RNA probe (B) but not with a
probe specific to poliovirus genomic RNA (E), indicating that the
signal is specific. The majority of negative-strand templates are
involved in RNA replication (Teterina et al., 2001). Therefore, these
Mock HRV1APDIMitotrackerGiantinGiantin/αHRV-1A
Fig. 2. Organelle marker staining of infected cells. WI-38 cells were mock infected or
infected with HRV-1A at four logs above the TCID50 for 24 h. Cells were fixed in
formaldehyde and stained with antibodies to Protein Disulphide Isomerase (PDI). At
24 h post infection, cells were stained with MitoTracker for 45 min before fixation.
Formaldehyde-fixed cells were stained for Giantin. Bottom row: cells were stained for
Giantin (red) and co-stained for HRV-1A capsid antibody (green), and fluorescent
signal overlaid with DIC images. Representative cells from each experiment were
imaged.
187C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
4. data indicate that altered Golgi morphologies likely represent active
sites of HRV-1A genome replication.
Electron microscopy of HRV-1A-infected cells
To further understand these cellular changes at the ultrastructural
level, we performed electron microscopy on mock-infected or HRV-
1A-infected WI-38 cells (Fig. 6). Infection was confirmed by removing
a portion of the culture before fixation and observing synchronous cell
lysis at 48–54 h.p.i. In mock-infected cells, we are able to identify
ordered stacks of membrane we identified as Golgi (closed white
arrowheads). The ultrastructure of cells infected with HRV-1A for 24 h
is distinct from that of uninfected cells. Elongated stacks of membranes
are rarely seen, and when they are, they are disorganized (open white
arrowheads). In HRV-1A infected cells, these stacks are not ordered,
while similar stacks visible in mock-infected cells are regularly spaced
and ordered. HRV-1A-infected cells also displayed larger, dark-
staining, ovoid vesicles of approximately 250–500 nM in diameter.
These vesicles, whose contents appear more electron dense than the
surrounding cytoplasm, can be seen throughout the cytoplasm of
infected cells. We do not observe structures in HRV-1A-infected cells
that have the size or characteristics of autophagosomes or autolyso-
somes. Based on these studies, HRV-1A appears to uniquely alter
cellular morphology, resulting in small vesicles distinct from those
observed in autophagic or PV-infected cells (Jackson et al., 2005).
In order to analyze the redistribution of Giantin signal during HRV-
1A infection, we performed immuno-EM analysis using our Giantin
antibody and gold-labeled secondary (Fig. 7). Golgi membranes are
more difficult to observe in our immuno-EM preparations due to
differences in the fixation and staining protocol. However, we were
able to detect Giantin staining in linear patterns, on apparent
membranes, in the cytosol of mock-infected cells (closed arrow-
heads). In contrast, HRV-1A infected cells showed a pattern of Giantin
staining near large vesicles (open arrowheads). The Giantin-staining
vesicles have light-staining contents in these images, possibly because
the vesicular contents were extracted as a result of the immuno-EM
preparation. Upon observation of over 100 cells, we did not find linear,
Golgi-like patterns of Giantin staining in HRV-1A infected cells.
Therefore, the vesicles we observe are likely to represent fragmented
Golgi membranes.
Expression of HRV-1A 3A protein
The 3A nonstructural protein from poliovirus is a 10kD transmem-
brane protein required for RNA replication (Berstein and Baltimore,
1988; Choe and Kirkegaard, 2004; Teterina et al., 2003). During PV
infection, 3A is found in the replication membranes. However, when
expressed in isolation, PV 3A localizes to the ER (Suhy et al., 2000). We
were interested in determining the effect of HRV-1A 3A protein
expression as well as its localization within cells. Lentivirus-based
constructs, which express both the protein of interest and GFP, were
generated with two versions of HRV-1A 3A. One has an HA antigenic
tag on the C-terminus, and the other is untagged. WI-38 cells were
infected and observed until GFP expression was visible (A,E,I) then
fixed and stained for Giantin (B,F,J) and HA (C,G,K). Production of 3A-
expressing lentivirus was not robust; in order to detect expression, we
needed to concentrate lentivirus by centrifugation. Even after
concentration, not every cell in our target cultures received lentivirus.
We presume that the low production of lentivirus is due to the known
toxicity of the 3A protein, since we did not have this problem with
6h 18h 24h12h
PVHRV-1AMOCK
Fig. 3. Time course of Giantin staining during infection. WI-38 cells were infected at four logs above the TCID50 for the indicated times with PV, HRV-1A, or mock infected. Cells were
then fixed and stained for Giantin as in Fig. 2. Cells were additionally stained for DAPI to visualize nuclei. Representative cells from each time point were imaged.
188 C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
5. lentiviruses that did not express 3A (Lama et al., 1992). However, this
allows for internal controls in each experiment. We have provided
fields that contain cells with and without lentivirus expression for
direct comparison (Fig. 8).
A vector-carrying lentivirus, which expresses GFP but no 3A
protein, displays normal Golgi morphology with continuous cisternae
clearly visible (A–D) indicating that the lentivirus system itself does
not alter Golgi staining. We were able to detect the HA-tagged form of
3A in lentivirus vector-expressing cells, which can further be identified
by the presence of GFP (E–H). We found that in 3A-HA expressing cells,
the pattern of Golgi staining changed, condensing to a juxtanuclear
region of the cell with distinct cisternae no longer visible. Cells in the
same field not receiving lentivirus (closed arrowheads) display a
normal pattern of Giantin staining. The pattern of 3A-HA staining
overlaps with Giantin staining, indicating that the tagged version of
HRV-1A 3A localizes to these altered Golgi membranes.
To determine if the HA antigenic tag altered the function of the 3A
protein, we expressed an untagged version of the protein (Fig. 8,
panels I–L). In GFP-positive cells (open arrowhead) the Giantin signal
is no longer in continuous lines but in diffuse puncta. While we do not
have the reagents to determine where the untagged 3A protein
localizes, this experiment does demonstrate a dramatic effect of 3A
expression on Golgi morphology. Taken together, the experiments in
Fig. 8 indicate that HRV-1A 3A is sufficient to induce changes in Golgi
morphology. In addition, the 3A-HA protein localizes to the altered
Golgi membranes.
Discussion
Our work here demonstrates that HRV-1A, like all positive-
stranded RNA viruses investigated to date, replicates its RNA in
association with cellular membranes. The novel finding about HRV-1A
genomic RNA replication is the source of the replication membranes.
A redistribution of the Golgi marker Giantin takes place during
infection, resulting in a condensation of the signal into a perinuclear
region, followed by puncta scattered throughout the cell. Negative-
DAPIGiantinGM130Merge
Mock HRV-1A
24h
Mock HRV-1A
72h
Fig. 4. Golgi redistribution in HRV1A-infected lung epithelial cells. BEAS-2B cells were infected at four logs above the TCID50, then fixed at 24 h.p.i. or 72 h.p.i. Cells were stained for
Giantin, GM130, and DAPI. Individual images are shown, and merged, bottom row.
189C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
6. stranded viral RNA, an intermediate in viral replication, also co-
localizes with a Golgi marker, indicating that viral RNA replication
occurs in association with fragmented Golgi membranes.
Our electron microscopy images (Fig. 6) of HRV-1A infected cells
reveals the presence of electron-dense vesicles of approximately
250–500 nm in diameter. These vesicles, which appear to be
multilamellar, are not visible in mock-infected WI-38 cells. In our
observations of at least 100 cells, there is a correlation between the
appearance of the electron-dense vesicles and the disorganization of
Golgi-like stacks in infected cells, although it is difficult to identify a
“Golgi-like stack” given the disorganized nature of membranes in
HRV-1A infected cells (Fig. 5). Our immunostained EM images
(Fig. 7) show Giantin staining on vesicles of approximately 500 nm
as well. Although the Giantin-stained vesicles are not electron
dense, we believe that extraction of vesicle contents may be the
result of preparation for immunostaining. Therefore, they are likely
the same 500-nm vesicles seen in conventional EM.
The 500-nm vesicles coincide with the only significant Giantin
staining in HRV-1A infected cells, so we believe they represent the
Giantin-stained puncta seen by immunofluorescence microscopy in
Figs. 2–4. Since a Golgi marker also co-localizes with negative-strand
viral RNA (Fig. 5) we believe that the electron-dense vesicles in Fig. 6
likely represent the sites of viral replication. Our model, unique to
HRV-1A of viruses studied, is that the Golgi fragments into vesicles
that serve as substrates for viral replication. It has been reported that
poliovirus causes fragmentation of the Golgi during late infection, but
that these membranes are not the sites of viral replication. (Beske
et al., 2007). At 24 h of a PV infection of WI-38 cells, we do not observe
Golgi fragmentation. Foot-and-mouth disease virus (FMDV) forms
replication sites near the Golgi apparatus, but Golgi markers are
specifically excluded from the replication membranes (Knox et al.,
2005). Therefore, this study marks the first demonstration, to our
knowledge, that the Golgi provides replication membranes to a
positive-strand RNA virus.
For insight into the possible mechanisms by which HRV-1A
hijacks Golgi membranes for replication, we have considered some
known pathways of Golgi fragmentation. For example, Brefeldin A,
which targets the ARF1 GTPase, can induce Golgi fragmentation.
The effect of Brefeldin A on the Golgi is morphologically similar to
that of HRV-1A infection (Hidalgo et al., 1992; Radulescu et al.,
2007). PV replication is extremely sensitive to Brefeldin A
treatment, suggesting that ARF1 function is important to the
Golgi RNA Probe Merge
A
D
G
B
E
H
C
F
I
PV probe
HRV-1A probe
HRV-1A probe
HRV-1AHRV-1AMOCK
Fig. 5. Localization of Golgi and HRV-1A negative-strand RNA. Cells were treated for 48 h with Organelle Lights Red Golgi (A,D,G) then infected with HRV-1A (A–F) or mock-infected
(G–I) for 24 h. After fixation, a positive sense Alexa Fluor 488-labeled HRV-1A RNA probe (B, H) or poliovirus RNA probe (E) was hybridized to the cells to detect negative-stranded
replication intermediates. Cells were then processed for imaging, and Golgi and RNA signals were merged (C, F, I).
190 C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
7. virus (Kirkegaard, 1992). Other picornaviruses vary in their
sensitivity to Brefeldin A (Gazina et al., 2002). ARF1 plays key
roles in membrane trafficking and has been implicated in Golgi
fragmentation during both mitosis and nocodazole treatment (Bui
et al., 2009; Tang et al., 2008). Guanine exchange factors (GEFs) for
ARF1 are recruited to poliovirus membranes by two different
poliovirus proteins (Belov et al., 2007). GBF1, an ARF1 GEF
recruited by poliovirus 3A, is also recruited by the 3A protein of
another picornavirus, Coxsackievirus B3 (Wessels et al., 2006).
However, the 3A proteins from HRV-2 and HRV-14 do not recruit
GBF1 to replication membranes, indicating that this is not universal
among picornaviruses (Wessels et al., 2006). We have found that
HRV-1A replication is extremely sensitive to Brefeldin A1. (Data not
shown). These data indicate that the importance of ARF1 in
picornavirus replication is independent of the organelle source of
the viral replication membrane.
The picornavirus 3A transmembrane protein is involved in
organelle rearrangements to generate replication membranes. In
this study we show that HRV-1A 3A can be expressed in isolation to
induce rearrangements of a Golgi marker within cells. In addition, an
epitope-tagged version co-localizes with the Golgi signal. These data,
along with our FISH data (Fig. 5), lead us to the model that HRV-1A
replicates its RNA in association with Golgi-derived vesicles, and that
the 3A protein plays a role in generating these replication membranes.
The effect of picornavirus 3A proteins on the Golgi is distinct
depending on the viral origin of the protein. When expressed in
isolation, poliovirus 3A localizes to the ER and induces swelling and
distension of that organelle, but no effects on the Golgi complex were
reported (Doedens et al., 1997; Suhy et al., 2000). Another group
demonstrated that expression of poliovirus 3A is capable of dispersing
the Golgi. The same study showed that myc-tagged 3A proteins from
Coxsackievirus B3, HRV-2, and HRV-14 localize to the Golgi complex
when expressed in cells (Wessels et al., 2006). Coxsackievirus B3 3A
protein can fragment the Golgi as well (Cornell et al., 2006).
We believe HRV-1A replication membranes derive from the Golgi
apparatus through an unknown mechanism. In contrast, PV replication
HRV-1A
Mock
Fig. 6. Electron Microscopy of Infected WI-38 lung fibroblasts. Cells were mock infected or infected with HRV-1A at four logs above the TCID50 for 24 h. Organized Golgi stacks can be
seen in Mock-infected cells (closed white arrowheads) but not HRV-1A-infected cells, which instead display disorganized areas of elongated membrane (open white arrowheads).
N=Nucleus. Rough ER can be seen as distinct structures (closed black arrowheads). Dark-staining vesicles approximately 250–500 nM across are observed in HRV-1A infected cells
(open black arrowheads). Note that there is no gold-particle labeling in these images; the small particles visible are likely to be virions. All bars=0.5 μM.
191C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
8. membranes likely derive from the ER, either through the autophago-
some or COPII pathways, or possibly both. When the 3A proteins of PV
and HRV-1A are expressed in isolation, each localizes to the organelle
hypothesized to be the source of replication membranes: the ER for PV,
and the Golgi for HRV-1A. This may be a mechanistic insight into a
picornavirus strategy for generating vesicles. The presence of the 3A
protein, possibly very early during infection, could mark an organelle
as the source of membranes for viral RNA replication.
In summary, we believe the marked difference in membrane
phenotype between genotypically similar viruses will lead to insights
regarding the mechanism of membrane generation by RNA viruses. If
3A is a common marker of organelles destined to become viral
replication membranes, then the differences between viral 3A
proteins can reveal novel localization signals and provide an
understanding of membrane rearrangements.
Materials and methods
Cells, virus, and plasmids
WI-38, 293T, and H1-HeLa cells were obtained from the American
Type Culture Collection (ATCC, Manassas, Virginia, United States) and
grown essentially according to ATCC protocols. WI-38 cells were grown
in Minimal Essential Medium (MEM) supplemented with 10% fetal
bovine serum and sodium pyruvate. 293T cells were grown in High
Glucose D-MEM supplemented with 5% calf serum and 5% fetal bovine
serum. H1-HeLa cells were grown in MEM supplemented with 10% calf
serum. BEAS-2B cells were a gift from Charles Myers (Department of
Pharmacology and Toxicology, Medical College of Wisconsin) and were
grown in D-MEM supplemented with 10% fetal bovine serum and 10%
LHC-9 complete medium (Invitrogen). All cell lines were maintained at
37 °C with 5% CO2 in the presence of Penicillin and Streptomycin. Viral
stocks were produced in H1- HeLa cells by transfection of in vitro
transcribed RNAs as described previously (Maynell et al., 1992;
Racaniello, 1984). Virus was diluted in PBS with 0.01% CaCl2, 0.01%
MgCl2 and cell absorption was carried out for 30–45 min at 37 °C before
addition of media. Stocks were titered by plaque assay on H1-HeLa cells
or TCID50 assay on 293T and WI-38 cells. 293T cells were transfected
using Effectene (Invitrogen) according to manufacturer's instructions.
Plasmid was first diluted 1:5 with empty vector to reduce expression
levels. The GFP-LC3 plasmid has been described previously and is
available from AddGene (www.addgene.org, plasmid 11546) (Jackson
et al., 2005). Lentivirus plasmids were provided by Dr. Richard Mulligan
(Mostoslavsky et al., 2006). Tamoxifen (Sigma) and rapamycin (LC
Labs) were dissolved in a 1:1 solution of DMSO:EtOH. 3-methyladenine
(Sigma) was dissolved directly into media.
Immunofluorescence
WI-38 cells grown on cover slips were infected at four logs above
the TCID50, fixed at room temperature (RT) for 10 min in 4%
formaldehyde, and permeabilized in PBS-BT (PBS with 3% BSA, 0.1%
Triton X-100) at RT for 15 min. Primary and secondary antibody
incubations were for 30 min at RT, and cells were subjected to three
washes with PBS-BT between antibody incubations. Mitochondria
were labeled with MitoTracker (Molecular Probes) according to
manufacturer's instructions. Antibody against Protein Disulphide
Isomerase (PDI, Abcam) was used at dilutions of 1:100. Antibody
MockMock
HRV-1A HRV-1A
Fig. 7. Immunostained electron microscopy of infected WI-38 lung fibroblasts. Samples were processed for immuno-EM using Giantin polyclonal antibody and gold-labeled
secondary antibody. Giantin staining can be seen in linear patterns in Mock-infected cells (closed arrowheads). For HRV-1A-infected cells, Giantin staining coincides with large
vesicles (open arrowheads) of approximately 500 nM in diameter. All bars=0.5 μM.
192 C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
9. against Giantin (Covance) was used at 1:1000. Antibody against HRV-
1A Capsid (ATCC) was used at 1:200. Appropriate Alexa Fluor-labeled
secondary antibodies were used for visualization at dilutions of 1:250
(Molecular Probes). Coverslips were mounted with Vectashield
(Vector Laboratories) and analyzed on a Nikon Eclipse TE2000-U
microscope with MetaMorph software. Images were minimally
processed in Adobe Photoshop 10.0.1.
Electron microscopy
WI-38 cells were placed in 10 cm dishes containing a coverslip. Cells
were infected with HRV-1A at four logs above the TCID50 for 24 h. Control
cells were mock infected for 24 h. The coverslip was removed from each
culture before fixation, placed in media, and cells were observed to
confirm lysis at 48–54 h post-infection. Remaining cells were washed in
0.1 M Sörensens phosphate buffer adjusted to pH 7.4+0.05 mM CaCl.
Fixation was performed in the dish with 1% glutaraldehyde+4%
paraformaldehyde in 0.1 M Sörensens buffer for 10 min. Cells were then
washed in 0.1 M Sörensens buffer three times for 5 min each. Post
fixation, cells were scraped from the plate, gently pelleted at 3000g for
5 min, and the pellets placed in freshly made reduced osmium tetroxide
(1% OsO4+1.25% potassium haxacyanoferrate in distilled water 2 h on
ice), dehydrated through graded methanol and processed into Embed 812
resin for EM observation of ultrathin (70 nm) sections. Cells were imaged
on a JEOL 2100 or a Hitachi H600 microscope. For immunostaining, cell
cultures were fixed in situ in a mixture of 4% paraformaldehyde and 0.1%
glutaraldehyde in Sörensen's buffer on ice for 30 min. Following fixation
the cells were washed (3×5 min) in buffer, scraped from the culture
dishes, and gently pelleted at 2000G for 10 min. Cell pellets were
processed into Lowicryl K4M resin using the progressively lower
temperature (PLT) method of Berryman and Rodewald following the
protocol of Burleigh et al. (Berryman and Rodewald, 1990; Burleigh et al.,
1993). After UV polymerization, ultrathin (60 nm) sections were cut,
mounted on formvar/carbon coated copper grids, and immuno-electron
microscopy performed on the sections by incubating sequentially on 25 μl
droplets in a humidified chamber. Anti-giantin was revealed using goat
anti-rabbit 10 nm conjugated gold colloidal reagent (Electron Microscopy
Sciences, Hatfield, PA). Double labeling was performed by first incubating
with anti-GM130, revealed using goat anti-mouse 6 nM conjugated gold
colloidal reagent, followed by 3×5-min washes in buffer then incubation
with anti-Giantin, revealed by goat-anti rabbit 10 nM gold conjugate.
Fluorescent in situ hybridization
For hybridization experiments, cells were labeled with “Organ-
elle Lights Golgi RFP” (Invitrogen) according to manufacturer's
instructions. This induces expression of an RFP-tagged portion of N-
acetylgalactosaminyltransferase-2, which localizes to Golgi stacks.
After 48 h, cells were infected with HRV-1A. 24 h later cells were
fixed and prepared for hybridization. Positive-stranded genomic
RNA was produced from full-length HRV-1A cDNA using the Ambion
MAXIscript kit in the presence of 488 nm labeled UTP (Molecular
Probes). The transcription product was treated with DNAse, and
unincorporated nucleotides were removed using Micro Bio Spin 6
Merge
3A-HA3AVector
HAGFP Golgi
A B
G H
I
FE
DC
LKJ
Fig. 8. Expression of HRV-1A 3A protein. Expression of 3A or 3A-HA proteins in the absence of HRV-1A infection. The lentivirus expression system used expresses GFP as a marker of
infection. Protein expression was allowed to proceed for 72 h before cells were processed for immunofluorescence. Giantin (Golgi marker) was detected with Alexa Fluor 647 nm
secondary antibody; HA tag was detected with Alexa Fluor 568 nm secondary antibody. Open arrowheads: cells which received lentivirus as indicated by GFP. Closed arrowheads:
cells that did not receive lentivirus.
193C.A. Quiner, W.T. Jackson / Virology 407 (2010) 185–195
10. columns (BioRad). The probes were subjected to alkaline hydrolysis
for 90 min at 60 °C in 40 mM NAF3/60 mM Na2CO3, pH 10.2 to
generate ~100 nt fragments (Cox et al., 1984). The hydrolysis
reaction was stopped by addition of 0.1 M NaAc pH 6/0.5% glacial
acetic acid, and probes were ethanol precipitated. Fragments greater
than 100 nt were removed using a Micro Bio Spin 30 column. HRV-
1A- and mock-infected WI-38 cells on cover slips were fixed and
permeabilized for 10 min in 0.2%Triton X-100/4% formaldehyde.
Following a PBS wash, aldehydes were quenched by adding PBS
containing 0.5 M ammonium chloride for 7 min. Cover slips were
placed in a moist chamber on top of 100 μl of hybridization buffer
(5% formamide, 10 mM Tris HCl pH 7.4, 600 mM NaCl, 10% dextran
sulfate, 10 mM DTT, 1% SDS, 200 μg/mL salmon sperm DNA)
containing 100 ng of probe. Probes were allowed to hybridize at
40 °C for 40 h. Cells were then washed in 0.1× SSC [0.1 M NaCl,
0.015 M Sodium Citrate] at RT for 10 min, three times and imaged.
Lentivirus vector production and expression
The 3A protein of HRV-1A was PCR amplified, with or without the
hemaggluttanin (HA) tag sequence, and cloned into the lentivirus
expression vector containing the cytomegalovirus (CMV) promoter
and sequence for GFP (Mostoslavsky et al., 2006). Lentivirus particles
were produced by transfecting five lentivirus-producing plasmids,
including the expression plasmid, into 293T HEK cells at 30%
confluency in a 10 cm dish, using TransIT-293 Transfection Reagent
(Mirus, MIR 2700). Media from the transfected 293T cells was
collected and replaced for three days. Supernatant was filtered
through a .45u PVDF membrane to create a cell-free solution and
was then centrifuged at 25,000 RPM for 2 h at 4 °C through a filter
sterilized 20% sucrose solution [20 g ultrapure sucrose, 100 mM NaCl,
20 mM HEPES (pH 7.4) and 1 mM EDTA]. Virus pellet was resus-
pended in 100 μl of PBS and vortexed every 20 min for 2 h. Tubes were
held at 4 °C in between vortexing, then removed. Remaining virus was
washed from the ultracentrifuge tube in 150 μl of PBS and combined
into 250 μl total virus stock. Virus was transferred onto PBS-washed
WI-38 cells on coverslips. Lentivirus particles were absorbed into cells
for 2 h at 37 °C, after which 1 mL of media was added to each well. The
media was changed 48 h post-infection, and cells were processed for
immunofluorescence upon observation of GFP expression, approxi-
mately 72 h post-infection. Imaging was performed on a Nikon Eclipse
Ti microscope with Nikon Elements software.
Acknowledgments
We thank Clive Wells for electron microscopy and Richard Mulligan
for providing lentivirus vectors. We acknowledge Charley Myers for
invaluable advice on the care and feeding of BEAS-2B cells. We are
grateful to Amy Hudson and Paula Traktman for experimental
suggestions and support. We also thank Kathryn Klein, Alexsia Richards,
and KathleenBoylefor criticalreadingof themanuscript. C.A.Q. thanksS.
D. for guidance. This work was supported by the Center for Infectious
Disease Research and the Advancing a Healthier Wisconsin program.
Appendix A. Supplementary data
Supplementary data to this article can be found online at
doi:10.1016/j.virol.2010.08.012.
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