Virology is the study of viruses, which were not well understood until the late 1800s. Early discoveries included Lady Montagu observing inoculation against smallpox in Turkey in the 18th century and Edward Jenner developing the smallpox vaccine using cowpox virus in 1798. In the late 19th century, the development of bacterial filters allowed viruses to be isolated and shown to be smaller than bacteria, causing diseases even when bacteria were removed. By the early 20th century, it was established that viruses could cause diseases in plants, animals, and humans and were distinct from bacteria.
Animal viruses are self replicating, intracellular parasites that completely rely on host animal cell for reproduction. They use the host's cellular components to replicate, then leaves the host cell to infect other cells.
Viruses, viroids, and prions are infectious agents. Viruses contain genetic material surrounded by a protein coat and infect all domains of life. Viroids are small, circular RNA molecules that infect plants and require a host RNA polymerase for replication. Prions are composed primarily of misfolded protein and cause neurodegenerative diseases in humans and animals by inducing normal protein molecules to take on their abnormal shape.
This document discusses virus classification systems. It provides an overview of the Baltimore classification system, which categorizes viruses based on their method of mRNA production. Group I viruses contain double-stranded DNA and produce mRNA through transcription. Group II viruses have single-stranded DNA and produce a double-stranded DNA intermediate before transcription. Group III viruses use double-stranded RNA, with one strand serving as the mRNA template. Group IV viruses contain single-stranded RNA with positive polarity that directly serves as mRNA.
Viroids are small, circular, non-encapsidated RNA molecules that infect plants and cause disease. They consist solely of nucleic acid and replicate autonomously using host cell machinery. Viroids range in size from 250-400 nucleotides and have various pathogenic effects on infected plants such as distorted growth and reduced yields. They replicate through rolling circle mechanisms using host RNA polymerases and can move systemically within the plant through the phloem. While most viroids only infect plants, the hepatitis delta virus is a human pathogen that requires hepatitis B for infection.
This document discusses viroids, virusoids, and prions. It defines viroids as small, circular, single-stranded RNA molecules without a protein coat that can infect plants. Viroids were first reported in 1971 and the most studied is the Potato Spindle Tuber Viroid. Virusoids are also circular single-stranded RNAs that depend on plant viruses for replication and encapsidation. Prions are small infectious particles composed of abnormally folded protein that can transmit their misfolded shape to normal variants of the same protein.
The document summarizes the life cycles of M13 and Mu viruses. M13 is a filamentous bacteriophage that infects E. coli. It has a single stranded DNA genome packed inside a protein capsid. It replicates through the attachment to and penetration of host cells, followed by replication of its genome and production of new virus particles. Mu is a temperate bacteriophage that can enter a lysogenic cycle by integrating its double stranded DNA into the host genome. It has an icosahedral head and tail structure and replicates through a "cut and paste" mechanism where its DNA integrates into the host chromosome.
This document defines viruses and summarizes their key characteristics and classification. It describes how viruses were first discovered through experiments filtering bacteria and plant extracts. Viruses are non-cellular particles that contain genetic material and invade living cells. They are smaller than bacteria, contain either DNA or RNA, and lack organelles. Viruses replicate only inside host cells and do not undergo binary fission. They have various structures depending on their nucleic acid arrangement and symmetry. Viruses are classified into groups based on their nucleic acids and ability to produce mRNA.
Virology is the study of viruses, which were not well understood until the late 1800s. Early discoveries included Lady Montagu observing inoculation against smallpox in Turkey in the 18th century and Edward Jenner developing the smallpox vaccine using cowpox virus in 1798. In the late 19th century, the development of bacterial filters allowed viruses to be isolated and shown to be smaller than bacteria, causing diseases even when bacteria were removed. By the early 20th century, it was established that viruses could cause diseases in plants, animals, and humans and were distinct from bacteria.
Animal viruses are self replicating, intracellular parasites that completely rely on host animal cell for reproduction. They use the host's cellular components to replicate, then leaves the host cell to infect other cells.
Viruses, viroids, and prions are infectious agents. Viruses contain genetic material surrounded by a protein coat and infect all domains of life. Viroids are small, circular RNA molecules that infect plants and require a host RNA polymerase for replication. Prions are composed primarily of misfolded protein and cause neurodegenerative diseases in humans and animals by inducing normal protein molecules to take on their abnormal shape.
This document discusses virus classification systems. It provides an overview of the Baltimore classification system, which categorizes viruses based on their method of mRNA production. Group I viruses contain double-stranded DNA and produce mRNA through transcription. Group II viruses have single-stranded DNA and produce a double-stranded DNA intermediate before transcription. Group III viruses use double-stranded RNA, with one strand serving as the mRNA template. Group IV viruses contain single-stranded RNA with positive polarity that directly serves as mRNA.
Viroids are small, circular, non-encapsidated RNA molecules that infect plants and cause disease. They consist solely of nucleic acid and replicate autonomously using host cell machinery. Viroids range in size from 250-400 nucleotides and have various pathogenic effects on infected plants such as distorted growth and reduced yields. They replicate through rolling circle mechanisms using host RNA polymerases and can move systemically within the plant through the phloem. While most viroids only infect plants, the hepatitis delta virus is a human pathogen that requires hepatitis B for infection.
This document discusses viroids, virusoids, and prions. It defines viroids as small, circular, single-stranded RNA molecules without a protein coat that can infect plants. Viroids were first reported in 1971 and the most studied is the Potato Spindle Tuber Viroid. Virusoids are also circular single-stranded RNAs that depend on plant viruses for replication and encapsidation. Prions are small infectious particles composed of abnormally folded protein that can transmit their misfolded shape to normal variants of the same protein.
The document summarizes the life cycles of M13 and Mu viruses. M13 is a filamentous bacteriophage that infects E. coli. It has a single stranded DNA genome packed inside a protein capsid. It replicates through the attachment to and penetration of host cells, followed by replication of its genome and production of new virus particles. Mu is a temperate bacteriophage that can enter a lysogenic cycle by integrating its double stranded DNA into the host genome. It has an icosahedral head and tail structure and replicates through a "cut and paste" mechanism where its DNA integrates into the host chromosome.
This document defines viruses and summarizes their key characteristics and classification. It describes how viruses were first discovered through experiments filtering bacteria and plant extracts. Viruses are non-cellular particles that contain genetic material and invade living cells. They are smaller than bacteria, contain either DNA or RNA, and lack organelles. Viruses replicate only inside host cells and do not undergo binary fission. They have various structures depending on their nucleic acid arrangement and symmetry. Viruses are classified into groups based on their nucleic acids and ability to produce mRNA.
Viriods are small circular RNA molecules without a protein coat that infect plants and animals. They replicate by hijacking the host's machinery and can cause diseases like potato spindle tuber disease in plants and Hepatitis D in humans. Prions are infectious protein particles that cause neurodegenerative diseases by changing the folding of normal host proteins. Examples include scrapie in sheep and mad cow disease in cattle. They are transmitted through ingestion and cause diseases by triggering apoptosis in the brain.
The document discusses the structure, classification, and replication of viruses. It begins by describing different viral structural components, including the capsid, envelope, and nucleic acid core. Viruses are classified based on their nucleic acid composition and structure, focusing on whether they have DNA or RNA genomes and whether they are enveloped or not. The document also examines different capsid structures like icosahedral, helical, and complex shapes. It provides examples of representative virus families and discusses how viruses are named.
Satellite viruses are sub-viral agents that depend on a helper virus for replication. The first reported satellite virus was Tobacco necrosis satellite virus. Satellite viruses contain nucleic acids enclosed in a protein coat and lack genes for replication. Satellite genomes can be single-stranded RNA, DNA, or circular RNA.
Satellite RNAs are small, linear or circular RNA strands found in certain multicomponent virus particles. They do not encode their own coat protein and depend on a helper virus for replication and encapsidation.
Viroids were discovered in 1971 and are small, circular, naked RNA molecules that replicate independently using host polymerases. Well-studied viroids include potato spindle tuber viroid and av
Viral assays allow for quantifying the number of animal viruses. While bacterial viruses can easily be grown, growing animal viruses is more difficult and expensive, often requiring whole animals or embryonating eggs. When animal cells grow as monolayers, a plaque assay can be used to count viruses by serially diluting the virus in a liquid medium and adding it to separate plates with monolayers of tissue culture cells. After the viruses attach, a semi-solid medium is added to restrict virus movement and allow only adjacent cells to become infected, forming visible plaques that can be counted.
The document discusses plant viruses. It begins by outlining learning objectives about plant virus infections, life cycles, transmission, structures, classification, replication, symptoms, identification, and control. It then provides details on the characteristics of plant viruses, including their non-cellular nature and dependence on host cells. The document discusses plant virus transmission methods, proteins, capsids, classifications, replication cycles for different types of viruses, symptoms, and methods of detection, identification, and control.
This document summarizes key information about viroids. It defines viroids as the smallest known infectious agents, consisting of small circular RNA molecules without capsids. The first viroid discovered was the potato spindle tuber viroid. Viroids are obligate parasites that replicate through a rolling circle mechanism in the nucleus of host cells. They have extensive intrastrand base pairing that allows them to avoid degradation. While viroids do not code for proteins, the hepatitis D viroid produces two RNA molecules, one that codes for the delta antigen protein. Viroids can cause economic losses through various plant diseases.
This document discusses the discovery and structure of viruses. It describes how Ivanovsky and Beijerinck discovered viruses through filtration experiments in the late 1800s. Viruses were found to be filterable, invisible agents that could not be grown in culture. The structure of viruses is then explained, noting they contain nucleic acids surrounded by a protein capsid, and some have an outer envelope. Viruses are much smaller than bacteria and lack cellular structures like organelles.
This document provides information about subviral pathogens including hepatitis delta virus (HDV), viroids, and prions. It discusses how HDV requires hepatitis B virus (HBV) to replicate and infect liver cells. Viroids are small pathogenic RNA molecules that cause plant diseases and lack a protein coat. Prions are infectious protein particles that cause transmissible spongiform encephalopathies in humans and animals like mad cow disease. The document also discusses viral diseases that affect agricultural crops and efforts to develop transgenic resistance.
The document summarizes the lytic and lysogenic cycles of viral replication. The lytic cycle involves a virus infecting a host cell, using the cell's machinery to replicate viral components, assembling new virus particles, and then causing the host cell to lyse, releasing new virus particles to infect other cells. The lysogenic cycle involves a temperate virus inserting its DNA into the host genome without killing the cell. The viral DNA is replicated along with the host DNA and remains dormant until inducing factors cause it to enter the lytic cycle. Lysogeny allows for transmission of genetic material between bacteria through specialized transduction.
This document discusses bacteriophage T4, a virus that infects E. coli bacteria. It has a complex protein coat and large double-stranded DNA genome. T4 uses the host cell's machinery to replicate and kills the host cell. T4 plays a role in cholera and diphtheria by carrying toxin genes that allow the bacteria to cause disease. Bacteriophage may be useful for treating antibiotic-resistant bacteria or infections where antibiotics cannot reach. T4 is also used in recombinant DNA technology.
- In the 1950s, a disease called kuru was observed among the Fore people of New Guinea that caused trembling, loss of motor control, and ultimately death.
- Kuru and other transmissible spongiform encephalopathies (TSEs) are caused by prion proteins, which are unique infectious proteins that can reproduce on their own and convert normal prion proteins into the abnormal infectious form.
- Prions are extremely resistant to heat and chemicals and can survive in the environment for many years. They infect the central nervous system and cause neurodegeneration through a chain reaction that multiplies copies of the infectious prion protein.
The document discusses different systems for classifying viruses. The main systems are the International Committee on Taxonomy of Viruses (ICTV) system and the Baltimore classification system. The ICTV system is based on phenotypic characteristics and defines virus taxonomy, naming conventions, and species. It aims to develop and maintain a universal virus taxonomy. The Baltimore classification system places viruses into one of seven groups based on their nucleic acid and replication strategy.
Bacteriophage introduction,Discovery of Phage,classification,Structure of Bacteriophage,Morphological Groups and Life Cycle of Bacteriophage and how it's attack on bacteria.
Vaccines work by activating the immune system through active immunization with live attenuated or killed pathogens. They provide long term immunity through memory B and T cells. Common types include killed/inactivated, attenuated, toxoid, recombinant, and DNA vaccines. Vaccines are manufactured through in vivo, in vitro, or chemical synthesis methods. Potential risks include vaccine strain infection, superantigen effects, and allergic reactions.
Viruses are composed of nucleic acids enclosed in a protein coat and are smaller than bacteria. They cannot replicate without a host cell and are considered non-living. A virus infects a host cell by attaching to receptors on its surface, and then either injects its nucleic acid inside or fuses with the host cell's membrane. Once inside, the virus takes over the cell's machinery to replicate itself through one of two cycles - lytic kills the host cell, while lysogenic integrates viral DNA into the host genome without immediately killing the cell. Retroviruses like HIV are unique as they use reverse transcriptase to transcribe their RNA into DNA before integrating into the host cell's chromosome.
Virus isolation in embryonated eggs, cell cultures and animals
Purification by centrifugation, chromatography and electrophoresis
3d models such as organoid cultures is not discussed
This document discusses virus taxonomy and classification. It provides:
1. An overview of virus classification systems, which are primarily based on phenotypic characteristics like morphology, nucleic acid type, host, and disease symptoms.
2. A history of virus naming conventions from early systems based on host names to current standardized systems like ICTV and Baltimore classifications.
3. Details on the International Committee on Taxonomy of Viruses (ICTV) which develops agreed-upon virus taxonomy, names, and classifications communicated internationally.
Viroids are the smallest known agents of infectious disease that cause disease in plants. They are composed of short strands of circular, single-stranded RNA that can self-replicate using the host cell's machinery. In 1971, viroids were discovered by Theodor Diener who found an acellular particle that infected potato plants, causing tuber deformities. There are 30 known viroid species classified into two families based on their structure and composition. Viroids can infect a wide range of plants such as potatoes, coconut palms, avocados, and citrus trees, causing diseases marked by symptoms like stunting, chlorosis, and fruit deformities.
This document provides an overview of virus classification and the Baltimore classification system. It begins with an introduction to naming conventions for viruses and general approaches to classification. It then describes the Baltimore classification in detail, which divides viruses into 7 classes based on their genome type and replication strategy. The classification focuses on whether the viral nucleic acids are DNA or RNA, and if they are single- or double-stranded. Key viral families are listed as examples for each class.
This document provides information on containing highly contagious diseases like panleukopenia and calicivirus in shelters. It discusses detection of the diseases through symptoms, determining what it is, and looking for unusual suspects. Isolation procedures are outlined, including how the diseases spread, how to kill them, and treatment options. Quarantine periods and procedures for reintroducing affected animals are also addressed. Specific information is provided on panleukopenia symptoms, testing challenges, vaccination for prevention, and handling an outbreak without euthanasia through isolation, treatment, and preventing further spread.
Viriods are small circular RNA molecules without a protein coat that infect plants and animals. They replicate by hijacking the host's machinery and can cause diseases like potato spindle tuber disease in plants and Hepatitis D in humans. Prions are infectious protein particles that cause neurodegenerative diseases by changing the folding of normal host proteins. Examples include scrapie in sheep and mad cow disease in cattle. They are transmitted through ingestion and cause diseases by triggering apoptosis in the brain.
The document discusses the structure, classification, and replication of viruses. It begins by describing different viral structural components, including the capsid, envelope, and nucleic acid core. Viruses are classified based on their nucleic acid composition and structure, focusing on whether they have DNA or RNA genomes and whether they are enveloped or not. The document also examines different capsid structures like icosahedral, helical, and complex shapes. It provides examples of representative virus families and discusses how viruses are named.
Satellite viruses are sub-viral agents that depend on a helper virus for replication. The first reported satellite virus was Tobacco necrosis satellite virus. Satellite viruses contain nucleic acids enclosed in a protein coat and lack genes for replication. Satellite genomes can be single-stranded RNA, DNA, or circular RNA.
Satellite RNAs are small, linear or circular RNA strands found in certain multicomponent virus particles. They do not encode their own coat protein and depend on a helper virus for replication and encapsidation.
Viroids were discovered in 1971 and are small, circular, naked RNA molecules that replicate independently using host polymerases. Well-studied viroids include potato spindle tuber viroid and av
Viral assays allow for quantifying the number of animal viruses. While bacterial viruses can easily be grown, growing animal viruses is more difficult and expensive, often requiring whole animals or embryonating eggs. When animal cells grow as monolayers, a plaque assay can be used to count viruses by serially diluting the virus in a liquid medium and adding it to separate plates with monolayers of tissue culture cells. After the viruses attach, a semi-solid medium is added to restrict virus movement and allow only adjacent cells to become infected, forming visible plaques that can be counted.
The document discusses plant viruses. It begins by outlining learning objectives about plant virus infections, life cycles, transmission, structures, classification, replication, symptoms, identification, and control. It then provides details on the characteristics of plant viruses, including their non-cellular nature and dependence on host cells. The document discusses plant virus transmission methods, proteins, capsids, classifications, replication cycles for different types of viruses, symptoms, and methods of detection, identification, and control.
This document summarizes key information about viroids. It defines viroids as the smallest known infectious agents, consisting of small circular RNA molecules without capsids. The first viroid discovered was the potato spindle tuber viroid. Viroids are obligate parasites that replicate through a rolling circle mechanism in the nucleus of host cells. They have extensive intrastrand base pairing that allows them to avoid degradation. While viroids do not code for proteins, the hepatitis D viroid produces two RNA molecules, one that codes for the delta antigen protein. Viroids can cause economic losses through various plant diseases.
This document discusses the discovery and structure of viruses. It describes how Ivanovsky and Beijerinck discovered viruses through filtration experiments in the late 1800s. Viruses were found to be filterable, invisible agents that could not be grown in culture. The structure of viruses is then explained, noting they contain nucleic acids surrounded by a protein capsid, and some have an outer envelope. Viruses are much smaller than bacteria and lack cellular structures like organelles.
This document provides information about subviral pathogens including hepatitis delta virus (HDV), viroids, and prions. It discusses how HDV requires hepatitis B virus (HBV) to replicate and infect liver cells. Viroids are small pathogenic RNA molecules that cause plant diseases and lack a protein coat. Prions are infectious protein particles that cause transmissible spongiform encephalopathies in humans and animals like mad cow disease. The document also discusses viral diseases that affect agricultural crops and efforts to develop transgenic resistance.
The document summarizes the lytic and lysogenic cycles of viral replication. The lytic cycle involves a virus infecting a host cell, using the cell's machinery to replicate viral components, assembling new virus particles, and then causing the host cell to lyse, releasing new virus particles to infect other cells. The lysogenic cycle involves a temperate virus inserting its DNA into the host genome without killing the cell. The viral DNA is replicated along with the host DNA and remains dormant until inducing factors cause it to enter the lytic cycle. Lysogeny allows for transmission of genetic material between bacteria through specialized transduction.
This document discusses bacteriophage T4, a virus that infects E. coli bacteria. It has a complex protein coat and large double-stranded DNA genome. T4 uses the host cell's machinery to replicate and kills the host cell. T4 plays a role in cholera and diphtheria by carrying toxin genes that allow the bacteria to cause disease. Bacteriophage may be useful for treating antibiotic-resistant bacteria or infections where antibiotics cannot reach. T4 is also used in recombinant DNA technology.
- In the 1950s, a disease called kuru was observed among the Fore people of New Guinea that caused trembling, loss of motor control, and ultimately death.
- Kuru and other transmissible spongiform encephalopathies (TSEs) are caused by prion proteins, which are unique infectious proteins that can reproduce on their own and convert normal prion proteins into the abnormal infectious form.
- Prions are extremely resistant to heat and chemicals and can survive in the environment for many years. They infect the central nervous system and cause neurodegeneration through a chain reaction that multiplies copies of the infectious prion protein.
The document discusses different systems for classifying viruses. The main systems are the International Committee on Taxonomy of Viruses (ICTV) system and the Baltimore classification system. The ICTV system is based on phenotypic characteristics and defines virus taxonomy, naming conventions, and species. It aims to develop and maintain a universal virus taxonomy. The Baltimore classification system places viruses into one of seven groups based on their nucleic acid and replication strategy.
Bacteriophage introduction,Discovery of Phage,classification,Structure of Bacteriophage,Morphological Groups and Life Cycle of Bacteriophage and how it's attack on bacteria.
Vaccines work by activating the immune system through active immunization with live attenuated or killed pathogens. They provide long term immunity through memory B and T cells. Common types include killed/inactivated, attenuated, toxoid, recombinant, and DNA vaccines. Vaccines are manufactured through in vivo, in vitro, or chemical synthesis methods. Potential risks include vaccine strain infection, superantigen effects, and allergic reactions.
Viruses are composed of nucleic acids enclosed in a protein coat and are smaller than bacteria. They cannot replicate without a host cell and are considered non-living. A virus infects a host cell by attaching to receptors on its surface, and then either injects its nucleic acid inside or fuses with the host cell's membrane. Once inside, the virus takes over the cell's machinery to replicate itself through one of two cycles - lytic kills the host cell, while lysogenic integrates viral DNA into the host genome without immediately killing the cell. Retroviruses like HIV are unique as they use reverse transcriptase to transcribe their RNA into DNA before integrating into the host cell's chromosome.
Virus isolation in embryonated eggs, cell cultures and animals
Purification by centrifugation, chromatography and electrophoresis
3d models such as organoid cultures is not discussed
This document discusses virus taxonomy and classification. It provides:
1. An overview of virus classification systems, which are primarily based on phenotypic characteristics like morphology, nucleic acid type, host, and disease symptoms.
2. A history of virus naming conventions from early systems based on host names to current standardized systems like ICTV and Baltimore classifications.
3. Details on the International Committee on Taxonomy of Viruses (ICTV) which develops agreed-upon virus taxonomy, names, and classifications communicated internationally.
Viroids are the smallest known agents of infectious disease that cause disease in plants. They are composed of short strands of circular, single-stranded RNA that can self-replicate using the host cell's machinery. In 1971, viroids were discovered by Theodor Diener who found an acellular particle that infected potato plants, causing tuber deformities. There are 30 known viroid species classified into two families based on their structure and composition. Viroids can infect a wide range of plants such as potatoes, coconut palms, avocados, and citrus trees, causing diseases marked by symptoms like stunting, chlorosis, and fruit deformities.
This document provides an overview of virus classification and the Baltimore classification system. It begins with an introduction to naming conventions for viruses and general approaches to classification. It then describes the Baltimore classification in detail, which divides viruses into 7 classes based on their genome type and replication strategy. The classification focuses on whether the viral nucleic acids are DNA or RNA, and if they are single- or double-stranded. Key viral families are listed as examples for each class.
This document provides information on containing highly contagious diseases like panleukopenia and calicivirus in shelters. It discusses detection of the diseases through symptoms, determining what it is, and looking for unusual suspects. Isolation procedures are outlined, including how the diseases spread, how to kill them, and treatment options. Quarantine periods and procedures for reintroducing affected animals are also addressed. Specific information is provided on panleukopenia symptoms, testing challenges, vaccination for prevention, and handling an outbreak without euthanasia through isolation, treatment, and preventing further spread.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
This document discusses the history and potential applications of bacteriophage therapy. It begins by introducing bacteriophages and their ability to lyse bacteria. It then provides examples of different types of phages and describes their life cycles. The document discusses the discovery of phages in the early 20th century and their use in the former Soviet Union to treat bacterial infections. It notes that antibiotic resistance has renewed interest in phage therapy as an alternative approach. The advantages and disadvantages of phage therapy over antibiotics are presented. The document concludes by stating that further studies are needed but that phages show promise as tailored treatments for multidrug-resistant bacteria.
Viruses are obligate intracellular parasites that can only multiply within host cells. They contain either DNA or RNA, and have a protein coat called a capsid that may be surrounded by an envelope. To replicate, a virus must invade a host cell, take over its machinery, and use it to produce new viral particles, which then go on to infect more cells. While viruses use living cells to multiply, they are not themselves considered living things.
Philanthropists and Fund Raisers in American Higher EducationGraham Garner
John Harvard bequeathed half his estate and library to a new school in Cambridge, Massachusetts in 1638. Elihu Yale made gifts to the Collegiate School of Connecticut from 1715 to 1718, which then changed its name to Yale University in his honor. Leland Stanford founded Stanford University in 1891 with unprecedented gifts. Methodist Bishop Holland Nimmons McTyeire established Vanderbilt University in Nashville in 1875 with $1 million from Cornelius Vanderbilt, though Vanderbilt was not religious and McTyeire was his cousin. Frederick Gates convinced John D. Rockefeller to give substantial funds to establish the University of Chicago in 1889.
This document provides an overview of transposable elements (TEs). It discusses that TEs are DNA sequences that can move within genomes. There are two major classes of TEs - retrotransposons which move via an RNA intermediate, and DNA transposons which move directly through a cut-and-paste or copy-and-paste mechanism. The document outlines different types of TEs found in bacteria, eukaryotes, and the human genome. It also discusses the impact of TEs in causing mutations and their applications in genetic engineering and mutagenesis experiments.
Prions are infectious agents that are composed of misfolded protein aggregates called PrP, lacking nucleic acid. They can cause fatal neurodegenerative diseases in humans and animals by converting normal PrP proteins into additional misfolded prions. Common prion diseases include Creutzfeldt-Jakob disease in humans, mad cow disease in cattle, and scrapie in sheep. Prions are highly resistant to sterilization by heat, chemicals, radiation, and are difficult to inactivate.
The document provides a history of discoveries related to DNA and genetics. It describes experiments in the 1940s-1950s that proved DNA is the genetic material responsible for inheritance. It details discoveries such as DNA's double helix structure and base pairing rules. The document also summarizes the mapping of the human genome and benefits of understanding the genome sequence.
La microbiología estudia los microorganismos como bacterias, virus y hongos. Se clasifica en agrícola, industrial, sanitaria, veterinaria, marina y cósmica, siendo la médica la que estudia los microbios que causan enfermedades. A través de la historia, científicos como Leeuwenhoek, Pasteur, Koch, Ivanovski, Fleming y Gilbert y Sanger hicieron importantes descubrimientos sobre microorganismos que avanzaron el conocimiento en esta área.
The document summarizes the structure and effects of prions, which are abnormal protein particles that cause fatal neurodegenerative diseases. Prions have two main forms: PrPc, the normal cellular prion protein consisting of four helices and two beta sheets, and PrPsc, the pathogenic form which has two helices and four beta sheets. PrPsc is highly resistant to heat and enzymes and converts PrPc into more PrPsc via a chain reaction, accumulating in the brain and gradually damaging neurons over time. Different prion strains preferentially affect different brain regions, ultimately leading to sponge-like brain tissue destruction and death from related diseases like Creutzfeldt-Jakob disease in humans and bovine
Bacterial transposons are mobile segments of DNA that can move within bacterial genomes. There are two main types: insertion sequences, which consist only of the DNA required for transposition; and composite transposons, which contain additional genes like antibiotic resistance genes flanked by insertion sequences. Transposons can move within genomes through replicative or conservative transposition and have played an important role in bacterial evolution and antibiotic resistance.
Viruses are small infectious agents that cannot replicate without a host cell. They contain either DNA or RNA as their genetic material and have a protein capsid that protects the genetic material. Some viruses have an additional envelope outside the capsid. Viruses hijack the machinery of host cells to replicate their genetic material and assemble new virus particles. The replication cycle involves attachment to and entry into the host cell, uncoating of the virus, replication of the genetic material, assembly of new virus particles, and release of progeny viruses. DNA viruses can either integrate into the host cell genome or replicate episomally. RNA viruses use RNA-dependent RNA polymerases or reverse transcriptase. Viruses may cause disease in hosts by
Este documento trata sobre el uso racional de los medicamentos. Explica que los medicamentos son sustancias que ayudan al organismo a curarse o protegerse de enfermedades. También describe los principales tipos de medicamentos como antibióticos y analgésicos, así como problemas comunes en el uso de medicamentos como la automedicación y dosis inadecuadas. Por último, ofrece medidas para mejorar el uso racional de medicamentos como la educación de profesionales sanitarios y pacientes.
El documento habla sobre el uso racional de los medicamentos. Explica que el uso racional implica recibir el medicamento adecuado, la dosis correcta, durante el tiempo adecuado y al menor costo. También advierte sobre las consecuencias del mal uso de medicamentos como la resistencia a antibióticos y las reacciones adversas. Recomienda siempre seguir las instrucciones médicas sobre los medicamentos.
The document lists all chemistry Nobel Laureates from 1901 to 2010. It provides the names of each year's laureate(s) and a brief description of their award-winning work. Some major achievements mentioned include discoveries relating to protein structure, organic synthesis methods, electron transfer reactions, and catalytic properties of RNA and enzymes.
Bacteria are single-celled microorganisms that can exist in three basic shapes - rods (called bacilli), spheres (called cocci), or spirals. They reproduce through binary fission and consume nutrients in various ways. Bacteria are classified based on several factors including their shape, staining properties, oxygen requirements, environment, and cell wall composition. Some key groups of bacteria include phototrophic bacteria, gliding bacteria, sheathed bacteria, and spirochetes.
This document discusses the different levels of protein structure: primary, secondary, tertiary, and quaternary. The primary structure refers to the amino acid sequence. Secondary structure includes alpha helices, beta sheets, and beta turns formed by hydrogen bonding between amino acids. Tertiary structure is the 3D conformation determined by interactions between side chains. Quaternary structure refers to the arrangement of multiple polypeptide subunits in multimeric proteins. The structures are determined through techniques like X-ray crystallography and NMR.
Transposable elements, or transposons, are DNA sequences that can move within genomes. There are two main classes of transposons: those that encode proteins to directly move the DNA element, and retrotransposons that move via an RNA intermediate using reverse transcriptase. Barbara McClintock discovered transposons in the 1940s and 1950s through her studies of maize, where she observed "jumping genes" that caused mosaic color patterns in kernels. Transposons are found in both prokaryotes and eukaryotes and can insert into new locations in genomes, sometimes causing mutations. They have played an important role in genome evolution and can continue to induce genetic variation.
Hepatitis viruses include Hepatitis A, B, C, D, E, and G. Hepatitis A virus is transmitted through the fecal-oral route and causes an acute infection. Hepatitis B virus is transmitted through blood or bodily fluids and can cause either an acute or chronic infection. Hepatitis C virus is transmitted through blood exposure and commonly causes a chronic infection. Prevention strategies include vaccination, immunoglobulin treatment, and screening of blood donors.
Viruses are small infectious particles that contain genetic material and reproduce by inserting their DNA or RNA into host cells. They are not considered living organisms as they do not have cells, lack metabolism, and are obligate intracellular parasites. Viruses can cause diseases in humans and other organisms. They reproduce through lytic and lysogenic cycles and can be transmitted through various methods like contact, air, body fluids, or insect bites depending on the virus. While viruses cause disease, they can also be used to deliver beneficial genes or drugs through viral vectors in applications like gene therapy or chemotherapy. Other infectious particles like viroids and prions also lack cells but can damage crops or brains.
Prokaryotes like archaebacteria and eubacteria are Earth's most abundant life forms. They are capable of living in many environments and obtaining energy from different sources. Bacteria are mostly single-celled organisms that lack nuclei and organelles, have circular chromosomes, and reproduce asexually or through conjugation. Viruses are not considered living as they require a host cell to reproduce, but they do evolve and regulate gene expression like other organisms. They enter host cells and use the cell's machinery to produce more viruses through a lytic or lysogenic infection cycle.
Viruses can replicate only inside living host cells. The replication process involves several steps:
1) Adsorption, where the virus attaches to the host cell receptor.
2) Penetration and uncoating, where the virus enters the cell and releases its nucleic acid.
3) Replication of the viral nucleic acid using host cell machinery. This results in many copies of the viral genome.
4) Synthesis of viral capsid proteins and assembly of new virus particles that are released from the host cell.
General Characters and Classification of Viruses. Includes ICTV classification and Baltimore classification of viruses. A brief explanation of the Viral structure and Lifecycle.
Viruses are the smallest infectious agents that can only replicate inside living host cells. They are metabolically inert and made up of either DNA or RNA surrounded by a protein coat called a capsid. Some viruses have an outer envelope as well. Viruses come in different shapes, sizes and structures depending on the symmetry of their capsids. They infect plants, animals and bacteria. Viruses replicate through lytic and lysogenic cycles where they take over the host cell machinery to produce new virus particles. While they exhibit some living properties like mutation and existing in different strains, viruses still lack many cellular functions and rely entirely on host cells for reproduction.
Viruses are non-living obligate intracellular parasites that infect all types of life forms. They consist of nucleic acid surrounded by a protein coat called a capsid. Some viruses also have an outer envelope. Viruses lack cellular structures and require a host cell to replicate. They enter the host cell and use the cell's machinery to produce more viruses. Viruses are classified based on their nucleic acid composition and morphology. Viral diseases are transmitted through various routes like droplets, sexual contact, blood, etc. Important viral diseases include influenza, hepatitis, HIV/AIDS, rabies, etc. Treatment focuses on controlling symptoms and developing vaccines.
Viruses are non-living particles that can only replicate inside host cells. They contain genetic material surrounded by a protein coat. While viruses exhibit some properties of life, such as the ability to evolve, they cannot perform all biological functions or maintain homeostasis. Viruses come in a variety of shapes and sizes and infect organisms as diverse as plants, animals, bacteria and archaea. They are classified according to their nucleic acid composition and structure. Viruses either enter a dormant latent stage within the host cell or undergo lytic replication, which results in host cell death. Treatment options for viral diseases include vaccines containing weakened live or killed viruses, interferons, antiviral drugs that target specific virus functions, and genetic engineering of attenuated viruses
Viruses have capsids made of protein subunits that enclose and protect their nucleic acid. Viruses come in two main shapes - helical or icosahedral - determined by the arrangement of capsomers in the capsid. Some viruses have an envelope in addition to the capsid.
Viral replication involves the virus binding to and entering a host cell, then using the cell's machinery to produce new viral components which are assembled and released to infect new cells. DNA and RNA viruses replicate via different mechanisms using virus-specific enzymes. Animal virus replication is more complex than bacterial viruses due to host cell complexity.
Growing viruses requires appropriate cell cultures or animal hosts that provide an environment where the virus can replicate
Viruses are parasites that can only replicate inside living host cells. They are made up of genetic material surrounded by a protein coat and have no cell structure of their own. Viruses come in many shapes and sizes but are typically 20-400 nanometers. They infect bacteria, plants, and animals. A virus replicates by entering a host cell, releasing its genetic material, and hijacking the cell's machinery to produce new virus particles that eventually cause the cell to burst and release new viruses. Viruses can have DNA or RNA as their genetic material and replicate through either a lytic or lysogenic cycle.
This document discusses viruses and provides information about their structure and life cycle. It defines viruses as non-cellular infectious particles composed of genetic material surrounded by a protein coat. Viruses are described as non-living because they contain no organelles and must use a host cell's machinery to replicate, but are also considered living because they can reproduce and mutate. The document outlines the differences between DNA and RNA viruses and describes viral capsids and envelopes. It explains the lytic and lysogenic replication cycles viruses use to infect host cells and how they are specific to certain kingdoms but not always specific species.
Viruses are non-cellular, obligate intracellular parasites that consist of nucleic acid (DNA or RNA) surrounded by a protein coat. They can only replicate inside living host cells by using the host's cellular machinery. Viruses come in a variety of shapes and sizes but are generally quite small, ranging from 18-400 nm. They are classified based on their nucleic acid composition and structure. Viruses infect both plants and animals and include important human pathogens.
This document summarizes key aspects of viruses discussed in Chapter 6. It describes viruses as obligate intracellular parasites that can only replicate inside host cells. Their basic structure is described as a nucleic acid core surrounded by a protein capsid, with some viruses also having an outer envelope. Viruses are classified based on their morphology and nucleic acid type. The viral life cycle is explained as penetration of the host cell, uncoating of the viral nucleic acid, biosynthesis of new viral components, assembly, and release of new virus particles. Viruses can cause either lytic or lysogenic infections in bacteria and either acute or latent infections in animals. Specific viruses discussed include influenza, HIV, and prions.
This document summarizes key aspects of viruses discussed in Chapter 6. It describes viruses as obligate intracellular parasites that can only replicate inside host cells. Their basic structure is described as a nucleic acid core surrounded by a protein capsid, with some viruses also having an outer envelope. Viruses are classified based on their morphology and nucleic acid type. The viral life cycle is explained as penetration of the host cell, uncoating of the viral contents, biosynthesis of new viral components, assembly, and release of new virus particles. Viruses can cause either lytic or lysogenic infections in bacteria and either acute or latent infections in animals. Specific viruses discussed include influenza, HIV, and prions.
Viruses are non-living infectious agents that contain genetic material (DNA or RNA) surrounded by a protein coat called a capsid. They can only replicate inside living host cells by hijacking the cell's machinery. Viruses come in different shapes and sizes, and some have an outer envelope. They infect bacteria, plants, and animals. To replicate, viruses enter cells, release their genetic material, and use the cell to produce new virus particles, which then exit and infect new host cells.
Viruses are microscopic particles that infect cells and rely on host cells to replicate. They contain genetic material in the form of DNA or RNA and have a protein coat. Viruses infect both eukaryotic and prokaryotic cells and differ from other organisms in their structure, biology, and reproduction. Viruses are classified into groups based on their structure and method of replication, with the Baltimore system categorizing viruses into 7 groups depending on their nucleic acid and method of replication.
This presentation gives a detail overview on Viruses - Morphology and Classification. The presentation is helpful for students of B. Pharm Second Year and those who wants to gain basic knowledge about Viruses.
Subject - Microbiology
This document provides an overview of viruses, including their history of discovery, characteristics, components, shapes, classification, bacteriophages, replication cycles, enveloped viruses, and other related infectious agents like viroids and prions. It discusses key scientists and experiments that contributed to the understanding of viruses. The replication cycles of lytic and lysogenic bacteriophages as well as enveloped DNA and RNA viruses are described.
The document provides information about viruses including their structure, classification, life cycles, and how they cause disease. It begins by describing the characteristics of viruses and explaining that they are not living or nonliving but exhibit traits of both. It then discusses the discovery of viruses and describes the structures of representative viruses like bacteriophage, influenza, and HIV. The modes of viral classification including Baltimore classification are explained. The document also covers the parasitic nature of viruses and how they depend on host cells for replication and survival. It describes the general steps in the viral life cycle including adsorption, penetration, replication, assembly and release. The lytic and lysogenic cycles of bacteriophages are explained in detail.
The document provides a brief history of smallpox and the development of vaccination. It describes how Edward Jenner used cowpox pus to inoculate and prevent smallpox in the 18th century. It then summarizes the World Health Organization's smallpox eradication program from 1967 to 1979 and contemporary concerns about smallpox being used for bioterrorism.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
ISO/IEC 27001, ISO/IEC 42001, and GDPR: Best Practices for Implementation and...PECB
Denis is a dynamic and results-driven Chief Information Officer (CIO) with a distinguished career spanning information systems analysis and technical project management. With a proven track record of spearheading the design and delivery of cutting-edge Information Management solutions, he has consistently elevated business operations, streamlined reporting functions, and maximized process efficiency.
Certified as an ISO/IEC 27001: Information Security Management Systems (ISMS) Lead Implementer, Data Protection Officer, and Cyber Risks Analyst, Denis brings a heightened focus on data security, privacy, and cyber resilience to every endeavor.
His expertise extends across a diverse spectrum of reporting, database, and web development applications, underpinned by an exceptional grasp of data storage and virtualization technologies. His proficiency in application testing, database administration, and data cleansing ensures seamless execution of complex projects.
What sets Denis apart is his comprehensive understanding of Business and Systems Analysis technologies, honed through involvement in all phases of the Software Development Lifecycle (SDLC). From meticulous requirements gathering to precise analysis, innovative design, rigorous development, thorough testing, and successful implementation, he has consistently delivered exceptional results.
Throughout his career, he has taken on multifaceted roles, from leading technical project management teams to owning solutions that drive operational excellence. His conscientious and proactive approach is unwavering, whether he is working independently or collaboratively within a team. His ability to connect with colleagues on a personal level underscores his commitment to fostering a harmonious and productive workplace environment.
Date: May 29, 2024
Tags: Information Security, ISO/IEC 27001, ISO/IEC 42001, Artificial Intelligence, GDPR
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हिंदी वर्णमाला पीपीटी, hindi alphabet PPT presentation, hindi varnamala PPT, Hindi Varnamala pdf, हिंदी स्वर, हिंदी व्यंजन, sikhiye hindi varnmala, dr. mulla adam ali, hindi language and literature, hindi alphabet with drawing, hindi alphabet pdf, hindi varnamala for childrens, hindi language, hindi varnamala practice for kids, https://www.drmullaadamali.com
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
How to Make a Field Mandatory in Odoo 17Celine George
In Odoo, making a field required can be done through both Python code and XML views. When you set the required attribute to True in Python code, it makes the field required across all views where it's used. Conversely, when you set the required attribute in XML views, it makes the field required only in the context of that particular view.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
How to Build a Module in Odoo 17 Using the Scaffold Method
Viruses, viroids, and prions
1. Viruses, Viroids, andViruses, Viroids, and
PrionsPrions
Bits and Pieces that causeBits and Pieces that cause
diseasedisease
2. Are Viruses LivingAre Viruses Living
or Non-living?or Non-living?
Viruses are both and neitherViruses are both and neither
They haveThey have some properties of lifesome properties of life
but not othersbut not others
For example, viruses can be killed,For example, viruses can be killed,
even crystallized like table salteven crystallized like table salt
However, theyHowever, they can’t maintain acan’t maintain a
constant internal stateconstant internal state
(homeostasis).(homeostasis).
3. What are Viruses?What are Viruses?
Viruses are geneticViruses are genetic
elements that replicateelements that replicate
independent of the cell’sindependent of the cell’s
chromosome(s) but notchromosome(s) but not
independently of theindependently of the
cells themselves.cells themselves.
Have anHave an extra cellularextra cellular
form-can exist ousideform-can exist ouside
the host(the host(VIRIONVIRION))
To multiply-should enterTo multiply-should enter
cell-cell-InfectionInfection
4. VirusesViruses
Viruses contain DNA or RNA and aViruses contain DNA or RNA and a
protein coatprotein coat
Some are enclosed by an envelopeSome are enclosed by an envelope
Naked/envelopedNaked/enveloped
Some viruses have spikesSome viruses have spikes
Most viruses infect only specificMost viruses infect only specific
types of cells in one hosttypes of cells in one host
Host range is determined byHost range is determined by
specific host attachment sites andspecific host attachment sites and
cellular factorscellular factors
5. CharacteristicsCharacteristics
Some viruses are enclosedSome viruses are enclosed
in an protectivein an protective envelopeenvelope
Some viruses may haveSome viruses may have
spikesspikes to help attach toto help attach to
the host cellthe host cell
Most viruses infect onlyMost viruses infect only
SPECIFIC host cellsSPECIFIC host cells
CAPSID
ENVELOPE
DNA
SPIKES
6. CharacteristicsCharacteristics
Non living structuresNon living structures
NoncellularNoncellular
Contain a protein coat called theContain a protein coat called the capsidcapsid
Have a nucleic acid core containingHave a nucleic acid core containing DNA orDNA or
RNARNA
Complete complex of NA and ProteinComplete complex of NA and Protein
packaged is called NUCLEOCAPSID.packaged is called NUCLEOCAPSID.
Capable of reproducingCapable of reproducing only when inside aonly when inside a
HOST cellHOST cell
7. CharacteristicsCharacteristics
ViralViral capsidscapsids
(coats) are made of(coats) are made of
individualindividual proteinprotein
subunitssubunits
Individual subunitsIndividual subunits
are calledare called
capsomeres.capsomeres.(20sides)(20sides)
Process –Process –
self-assemblyself-assembly
CAPSOMERES
8. CharacteristicsCharacteristics
Outside of host cells,Outside of host cells,
viruses areviruses are inactiveinactive
Lack ribosomes andLack ribosomes and
enzymesenzymes needed forneeded for
metabolismmetabolism
Use theUse the raw materialsraw materials
and enzymes of the hostand enzymes of the host
cell to be able tocell to be able to
reproducereproduce
EBOLA VIRUS
HIV VIRUS
9. CharacteristicsCharacteristics
Some viruses causeSome viruses cause diseasedisease
Smallpox, measles,Smallpox, measles,
mononucleosis, influenza, colds,mononucleosis, influenza, colds,
warts, AIDS, Ebolawarts, AIDS, Ebola
Some viruses may causeSome viruses may cause somesome
cancers like leukemiacancers like leukemia
Virus-free cells areVirus-free cells are rarerare
MEASLES
11. Tobacco Mosaic VirusTobacco Mosaic Virus
Wendell StanleyWendell Stanley
(1935) crystallized(1935) crystallized
sapsap from sickfrom sick
tobacco plantstobacco plants
He discoveredHe discovered
viruses were made ofviruses were made of
nucleic acid andnucleic acid and
proteinprotein
12. Discovery of VirusesDiscovery of Viruses
BeijerinckBeijerinck (1897) coined(1897) coined
the Latin name “virus”the Latin name “virus”
meaningmeaning poisonpoison
He studiedHe studied filtered plantfiltered plant
juicesjuices & found they& found they
caused healthy plants tocaused healthy plants to
become sickbecome sick
13. SmallpoxSmallpox
Edward JennerEdward Jenner
(1796)(1796) developed adeveloped a
smallpox vaccine usingsmallpox vaccine using
mildermilder cowpox virusescowpox viruses
Deadly viruses areDeadly viruses are
said to besaid to be virulentvirulent
Smallpox has beenSmallpox has been
eradicated in theeradicated in the
world todayworld today
14. Viewing VirusesViewing Viruses
Viruses areViruses are smallersmaller
than the smallest cellthan the smallest cell
Measured in nmMeasured in nm(20-300nm)(20-300nm)
Viruses couldn’t beViruses couldn’t be
seen until theseen until the electronelectron
microscopemicroscope waswas
invented in theinvented in the 2020thth
centurycentury
17. Viral ShapesViral Shapes
Viruses come in aViruses come in a variety of shapesvariety of shapes
Some may beSome may be helicalhelical shape like theshape like the EbolaEbola
virusvirus
Some may beSome may be polyhedralpolyhedral (ICOSAHEDRAL)(ICOSAHEDRAL)
shapes like theshapes like the influenzainfluenza virusvirus
Others have moreOthers have more complex shapescomplex shapes likelike
bacteriophagesbacteriophages
22. Viral TaxonomyViral Taxonomy
FamilyFamily names end innames end in -viridae-viridae
GenusGenus names end innames end in -virus-virus
Viral speciesViral species: A group of viruses sharing: A group of viruses sharing
the same genetic information andthe same genetic information and
ecological niche (host).ecological niche (host).
Common namesCommon names are used forare used for speciesspecies
SubspeciesSubspecies are designated by aare designated by a numbernumber
29. HOST they infect;HOST they infect;bacteriophages,animal,plantbacteriophages,animal,plant
RNA or DNA Virus: ss or dsRNA or DNA Virus: ss or ds
RNA DNA virusesRNA DNA viruses
Ss RNA = Retroviruses; ds DNA= HepadnavirusSs RNA = Retroviruses; ds DNA= Hepadnavirus
Do or do NOT have an envelopeDo or do NOT have an envelope
Capsid shape:Capsid shape:helical ;icosahedral; complexhelical ;icosahedral; complex
Used for VirusUsed for Virus
IdentificationIdentification
31. PhagesPhages
Viruses that attackViruses that attack
bacteria are calledbacteria are called
bacteriophagebacteriophage or justor just
phagephage
T-phagesT-phages are a specificare a specific
class of bacteriophagesclass of bacteriophages
withwith icosahedral headsicosahedral heads,,
double-strandeddouble-stranded DNADNA,,
andand tailstails
32. T-phagesT-phages
The most commonly studiedThe most commonly studied
T-phages areT-phages are T4 and T 7T4 and T 7
They infectThey infect E. coliE. coli , an, an
intestinal bacteriaintestinal bacteria
Six smallSix small spikesspikes at the baseat the base
of a contractile tail are usedof a contractile tail are used
toto attach to the host cellattach to the host cell
Inject viral DNAInject viral DNA into cellinto cell
35. Diagram of T-4Diagram of T-4
BacteriophageBacteriophage
Head withHead with 2020
triangulartriangular
surfacessurfaces
Capsid containsCapsid contains
DNADNA
Head & tailHead & tail
fibers made offibers made of
proteinprotein
37. Characteristics ofCharacteristics of
RetrovirusesRetroviruses
ContainContain RNARNA, not DNA, not DNA
FamilyFamily RetroviridaeRetroviridae
Contain enzyme calledContain enzyme called ReverseReverse
TranscriptaseTranscriptase
When a retrovirus infects a cell, itWhen a retrovirus infects a cell, it
injects itsinjects its RNA and reverseRNA and reverse
transcriptase enzymetranscriptase enzyme into theinto the
cytoplasm of that cellcytoplasm of that cell
39. RetrovirusesRetroviruses
The enzymeThe enzyme reversereverse
transcriptasetranscriptase (or RTase),(or RTase),
which causes synthesiswhich causes synthesis
of a complementary DNAof a complementary DNA
moleculemolecule (cDNA)(cDNA) usingusing
virus RNA as a templatevirus RNA as a template
RTase
40. RetrovirusesRetroviruses
HIV, the AIDSHIV, the AIDS
virus, is a retrovirusvirus, is a retrovirus
Feline LeukemiaFeline Leukemia
VirusVirus is also ais also a
retrovirusretrovirus
41. Enzymes in virionsEnzymes in virions
LysozymeLysozyme
RNA dependant DNA polymerase-RNA dependant DNA polymerase-
Reverse transcriptaseReverse transcriptase
NeuraminadasesNeuraminadases
43. ViroidsViroids
Small, circular ss-Small, circular ss-
RNARNA moleculesmolecules withoutwithout
a protein coata protein coat
InfectInfect plantsplants
Do not infect animalsDo not infect animals
Potato faminePotato famine inin
IrelandIreland
Resemble intronsResemble introns cutcut
out of eukaryoticout of eukaryotic
Mechanism ofMechanism of
infection unclearinfection unclear
44. ViriodsViriods
ssRNAssRNA
Size from 246 to 399 nmSize from 246 to 399 nm
Show considerable sequence homologyShow considerable sequence homology
Cause a no of plant diseases:Cause a no of plant diseases:
Coconut cadang cadang viroid-246 nucleotidesCoconut cadang cadang viroid-246 nucleotides
Citrus exocortis viroid- 375 nucleotidesCitrus exocortis viroid- 375 nucleotides
Potato spindle tuber viroid -359 nucleotidesPotato spindle tuber viroid -359 nucleotides
45. Extracellular form=naked RNAExtracellular form=naked RNA
RNA has no protein encoding geneRNA has no protein encoding gene
Viroid totally dep on host for its replication.Viroid totally dep on host for its replication.
Tho’ ssRNA circular,secondary structure=resemblingTho’ ssRNA circular,secondary structure=resembling
ds molecule with closed ends.ds molecule with closed ends.
Enters plant through wound:by insect or mechanicalEnters plant through wound:by insect or mechanical
damage.damage.
Replicated by plant RNA polymerasesReplicated by plant RNA polymerases
Symptomless or mild to lethal symptomsSymptomless or mild to lethal symptoms
Severe symptoms growth related.-are type ofSevere symptoms growth related.-are type of
regulatory RNAregulatory RNA
46. PrionsPrionsPrions arePrions are “infectious proteins”“infectious proteins”
They are normal body proteinsThey are normal body proteins
that getthat get converted into an alternateconverted into an alternate
configurationconfiguration by contact with otherby contact with other
prion proteinsprion proteins
They haveThey have no DNA or RNAno DNA or RNA
The main protein involved in humanThe main protein involved in human
andand mammalian prion diseasesmammalian prion diseases isis
calledcalled “PrP”(neurons)“PrP”(neurons)
Prions don’t simply subvert hostPrions don’t simply subvert host
enzymes in the cell but convert aenzymes in the cell but convert a
normal protein into a selfnormal protein into a self
propagating conformational state.propagating conformational state.
48. Prion DiseasesPrion Diseases
Prions formPrions form insolubleinsoluble
deposits in the braindeposits in the brain
Causes neurons toCauses neurons to
rapidly degeneration.rapidly degeneration.
Mad cow diseaseMad cow disease
(bovine spongiform(bovine spongiform
encephalitis: BSE) is anencephalitis: BSE) is an
exampleexample
People in New GuineaPeople in New Guinea
used to suffer fromused to suffer from
kurukuru, which they got, which they got
from eating the brainsfrom eating the brains
of their enemiesof their enemies
49. PrionsPrions
Distict extracellular formDistict extracellular form
Cause scrapie in sheepCause scrapie in sheep
BSE in cattleBSE in cattle
Chronic wasting disease in deer and elkChronic wasting disease in deer and elk
Kuru and Creutzfeldt-Jacob disease CJD in humansKuru and Creutzfeldt-Jacob disease CJD in humans
Prion diseases =transmissible spongiformPrion diseases =transmissible spongiform
encephalopathies –TSEencephalopathies –TSE
1997-Stanley Pruisner –noble prize1997-Stanley Pruisner –noble prize
1996 prion causing BSE can cause a new variant nv-1996 prion causing BSE can cause a new variant nv-
CJD in humans by consuming beef with BSECJD in humans by consuming beef with BSE
51. Viral AttackViral Attack
Viruses are very specific as to whichViruses are very specific as to which
species they attackspecies they attack
HOST specificHOST specific
Humans rarely share viral diseases withHumans rarely share viral diseases with
other animalsother animals
Eukaryotic virusesEukaryotic viruses usually haveusually have
protectiveprotective envelopesenvelopes made from themade from the
host cell membranehost cell membrane
52. Lytic vs LysogenicLytic vs Lysogenic
Lytic cycleLytic cycle
Phage causes lysis and death ofPhage causes lysis and death of
host cellhost cell
Lysogenic cycleLysogenic cycle
Prophage DNA incorporated inProphage DNA incorporated in
host DNAhost DNA
53. 5 Steps of Lytic Cycle5 Steps of Lytic Cycle
1.1. AttachmentAttachment to the cellto the cell
2.2. PenetrationPenetration (injection) of viral DNA or(injection) of viral DNA or
RNARNA
3.3. Replication (Biosynthesis)Replication (Biosynthesis) of new viralof new viral
proteins and nucleic acidsproteins and nucleic acids
4.4. AssemblyAssembly (Maturation)(Maturation) of the newof the new
virusesviruses
5.5. ReleaseRelease of the new viruses into theof the new viruses into the
environment (cell lyses)environment (cell lyses)
54. AttachmentAttachment Phage attaches by tail fibersPhage attaches by tail fibers
to host cell1to host cell1
PenetrationPenetration Phage lysozyme opens cellPhage lysozyme opens cell
wall, tail sheath contracts to force tailwall, tail sheath contracts to force tail
core and DNA into cellcore and DNA into cell
BiosynthesisBiosynthesis Production of phage DNAProduction of phage DNA
and proteinsand proteins
MaturationMaturation Assembly of phage particlesAssembly of phage particles
ReleaseRelease Phage lysozyme breaks cell wallPhage lysozyme breaks cell wall
Lytic Cycle ReviewLytic Cycle Review
56. Attachment:
Phage
attaches to
host cell.
Penetration:
Phage pnetrates
host cell and
injects its DNA.
Merozoites
released into
bloodsteam from
liver may infect
new red blood cells
1
2
3
Bacterial
cell wall
Bacterial
chromosome
Capsid DNA
Capsid
Sheath
Tail fiber
Base plate
Pin
Cell wall
Tail
Plasma membrane
Sheath contracted
Tail core
57. 4 Maturation:
Viral components
are assembled into
virions.
Tail
5 Release:
Host cell lyses
and new virions
are released.
DNA
Capsid
Tail fibers
59. Viral LatencyViral Latency
Some viruses have the ability to becomeSome viruses have the ability to become
dormantdormant inside the cellinside the cell
CalledCalled latent viruseslatent viruses
They may remainThey may remain inactiveinactive for longfor long
periods of time (years)periods of time (years)
Later, theyLater, they activateactivate to produce newto produce new
virusesviruses in response to some externalin response to some external
signalsignal
HIVHIV andand HerpesHerpes viruses are examplesviruses are examples
60. Lysogenic CycleLysogenic Cycle
Phage DNAPhage DNA injectedinjected
into host cellinto host cell
Viral DNA joins hostViral DNA joins host
DNA forming aDNA forming a prophageprophage
When anWhen an activationactivation
signalsignal occurs, the phageoccurs, the phage
DNA starts replicatingDNA starts replicating
61. Lysogenic CycleLysogenic Cycle
Viral DNA (part ofViral DNA (part of
prophage) may stayprophage) may stay
inactiveinactive in host cell forin host cell for
long periods of timelong periods of time
Replicated during eachReplicated during each
binary fissionbinary fission
Over time,Over time, many cellsmany cells
form containing theform containing the
prophagesprophages
62. Viral LatencyViral Latency
Once aOnce a prophage cell is activatedprophage cell is activated, host, host
cell enters the lytic cellcell enters the lytic cell
New viruses form a & theNew viruses form a & the cell lysescell lyses
(bursts)(bursts)
Virus said to beVirus said to be virulent (deadly)virulent (deadly)
INACTIVE STAGE
ACTIVE
STAGE
65. Latency in EukaryotesLatency in Eukaryotes
SomeSome eukaryoticeukaryotic
virusesviruses remain dormantremain dormant
for many years in thefor many years in the
nervous system tissuesnervous system tissues
ChickenpoxChickenpox (caused by(caused by
the virusthe virus VaricellaVaricella
zosterzoster) is a childhood) is a childhood
infectioninfection
It canIt can reappear later inreappear later in
life aslife as shinglesshingles, a painful, a painful
itching rash limited toitching rash limited to
small areas of the bodysmall areas of the body
SHINGLES
66. Latency in EukaryotesLatency in Eukaryotes
HerpesHerpes viruses alsoviruses also
becomebecome latent in thelatent in the
nervous systemnervous system
A herpes infectionA herpes infection lastslasts
for a person’s lifetimefor a person’s lifetime
Genital herpesGenital herpes (Herpes(Herpes
Simplex 2)Simplex 2)
Cold sores or feverCold sores or fever
blistersblisters (Herpes(Herpes
Simplex1)Simplex1)
SKIN TO SKIN CONTACT
PASSED AT BIRTH TO
BABY
68. VaccinesVaccines
AnAn attenuated virusattenuated virus is a weakened, lessis a weakened, less
vigorous virusvigorous virus
““Attenuate"Attenuate" refers to procedures thatrefers to procedures that
weaken an agent of diseaseweaken an agent of disease (heating)(heating)
AA vaccinevaccine against a viral disease can beagainst a viral disease can be
made from an attenuated, less virulentmade from an attenuated, less virulent
strain of the virusstrain of the virus
Attenuated virus is capable ofAttenuated virus is capable of stimulatingstimulating
an immune responsean immune response and creatingand creating immunity,immunity,
but not causing illnessbut not causing illness
70. Growing VirusesGrowing Viruses
Viruses must beViruses must be
grown in livinggrown in living
cells.cells.
BacteriophagesBacteriophages
form plaques onform plaques on
a lawn ofa lawn of
bacteria.bacteria.
Figure 13.6
71. Growing VirusesGrowing Viruses
AnimalAnimal
viruses mayviruses may
be grown inbe grown in
living animalsliving animals
or inor in
embryonatedembryonated
eggs.eggs.
Figure 13.7
72. Growing VirusesGrowing Viruses
Animal and plants viruses may be grownAnimal and plants viruses may be grown
in cell culture.in cell culture.
Continuous cell lines may be maintainedContinuous cell lines may be maintained
indefinitely.indefinitely.
Figure 13.8
73. Cytopathic effectsCytopathic effects
Serological testsSerological tests
Detect antibodies against viruses in a patientDetect antibodies against viruses in a patient
Use antibodies to identify viruses in neutralizationUse antibodies to identify viruses in neutralization
tests, viral hemagglutination, and Western blottests, viral hemagglutination, and Western blot
Nucleic acidsNucleic acids
RFLPsRFLPs
PCRPCR
Virus IdentificationVirus Identification
75. Multiplication of AnimalMultiplication of Animal
virusesviruses
AttachmentAttachment Viruses attaches to cellViruses attaches to cell
membranemembrane
PenetrationPenetration By endocytosis or fusionBy endocytosis or fusion
UncoatingUncoating By viral or host enzymesBy viral or host enzymes
BiosynthesisBiosynthesis Production of nucleic acid andProduction of nucleic acid and
proteinsproteins
MaturationMaturation Nucleic acid and capsid proteinsNucleic acid and capsid proteins
assembleassemble
ReleaseRelease By budding (enveloped viruses) orBy budding (enveloped viruses) or
rupturerupture
77. Release of an enveloped virus byRelease of an enveloped virus by
buddingbudding
Figure 13.20
78. Multiplication of DNA VirusMultiplication of DNA Virus
Figure 13.15
Virion attaches to host cell
Virion penetrates
cell and its DNA is
uncoated
Early transcription and
translation; enzymes are
synthesized
1
2
3
DNA
Late transcription;
DNA is replicated
4
Late translation;
capsid proteins
are synthesized
5
Virions mature6
Capsid
Papovavirus
Host cell
DNA
Cytoplasm
Virions are released7
Capsid proteins
mRNA
79. Pathways of Multiplication forPathways of Multiplication for
RNA-Containing VirusesRNA-Containing Viruses
Figure 13.17
80. Multiplication of a RetrovirusMultiplication of a Retrovirus
Figure 13.19
Retrovirus penetrates
host cell.
Virion penetrates
cell and its DNA is
uncoated
The new viral DNA is
tranported into the host cell’s
nucleus and integrated as a
provirus. The provirus may
divide indefinitely with the
host cell DNA.
1
2
3
DNA
Transcription of the
provirus may also occur,
producing RNA for new
retrovirus genomes and
RNA that codes for the
retrovirus capsid and
envelope proteins.
4
Mature
retrovirus
leaves host
cell, acquiring
an envelope as
it buds out.
5
Capsid
Reverse
transcriptase
Virus Two identical + stands of RNA
DNA of one of the host
cell’s chromosomes
Provirus
Host
cell
Reverse
transcriptase
Viral RNA
RNA
Viral proteins
Identical
strands of
RNA
81. Activated oncogenes transform normalActivated oncogenes transform normal
cells into cancerous cells.cells into cancerous cells.
Transformed cells have increased growth,Transformed cells have increased growth,
loss of contact inhibition, tumor specificloss of contact inhibition, tumor specific
transplant and T antigens.transplant and T antigens.
The genetic material of oncogenic virusesThe genetic material of oncogenic viruses
becomes integrated into the host cell'sbecomes integrated into the host cell's
DNA.DNA.
CancerCancer
82. Oncogenic DNAOncogenic DNA
VirusesViruses
AdenoviridaeAdenoviridae
HeresviridaeHeresviridae
PoxviridaePoxviridae
PapovaviridaePapovaviridae
HepadnaviridaeHepadnaviridae
Oncogenic VirusesOncogenic Viruses
Oncogenic RNAOncogenic RNA
virusesviruses
RetroviridaeRetroviridae
Viral RNA isViral RNA is
transcribed to DNAtranscribed to DNA
which can integratewhich can integrate
into host DNAinto host DNA
HTLV 1HTLV 1
HTLV 2HTLV 2
83. Latent vs PersistentLatent vs Persistent
Latent Viral InfectionsLatent Viral Infections
Virus remains in asymptomatic host cell forVirus remains in asymptomatic host cell for
long periodslong periods
Cold sores, shinglesCold sores, shingles
Persistent Viral InfectionsPersistent Viral Infections
Disease processes occurs over a long period,Disease processes occurs over a long period,
generally fatalgenerally fatal
Subacute sclerosing panencephalitis (measlesSubacute sclerosing panencephalitis (measles
virus)virus)
84. Figure 13.22
Plant VirusesPlant Viruses
Plant virusesPlant viruses
enter throughenter through
wounds or viawounds or via
insectsinsects
ViroidsViroids
Viroids areViroids are
infectiousinfectious
RNA; potatoRNA; potato
spindle tuberspindle tuber
diseasedisease
90. SimplexvirusSimplexvirus (HHV1 and HHV 2)(HHV1 and HHV 2)
VaricellavirusVaricellavirus (HHV 3)(HHV 3)
LymphocryptovirusLymphocryptovirus (HHV 4)(HHV 4)
CytomegalovirusCytomegalovirus (HHV 5)(HHV 5)
RoseolovirusRoseolovirus (HHV 6)(HHV 6)
HHV 7HHV 7
Kaposi's sarcoma (HHV 8)Kaposi's sarcoma (HHV 8)
Some herpesviruses can remainSome herpesviruses can remain
latent in host cellslatent in host cells
Double-stranded DNA,Double-stranded DNA,
nonenveloped virusesnonenveloped viruses
91. Double-stranded DNA,Double-stranded DNA,
nonenveloped virusesnonenveloped viruses
HepadnavirusHepadnavirus
(Hepatitis B(Hepatitis B
virus)virus)
Use reverseUse reverse
transcriptase totranscriptase to
produce DNAproduce DNA
from mRNAfrom mRNA
94. Single-stranded RNA, +Single-stranded RNA, +
strand, nonenvelopedstrand, nonenveloped
AlphavirusAlphavirus
Alphaviruses areAlphaviruses are
transmitted bytransmitted by
arthropods;arthropods;
include EEE,include EEE,
WEEWEE
RubivirusRubivirus
(rubella virus)(rubella virus)
95. Single-stranded RNA, +Single-stranded RNA, +
strand, nonenvelopedstrand, nonenveloped
ArbovirusesArboviruses cancan
replicate inreplicate in
arthropods; includearthropods; include
yellow fever, dengue,yellow fever, dengue,
SLE, and West NileSLE, and West Nile
virusesviruses
Hepatitis C virusHepatitis C virus
104. LentivirusLentivirus (HIV)(HIV)
Oncogenic virusesOncogenic viruses
Use reverseUse reverse
transcriptasetranscriptase
to produceto produce
DNA from viralDNA from viral
genomegenome
Includes allIncludes all
RNA tumorRNA tumor
virusesviruses
Single-stranded RNA, two RNA strands,Single-stranded RNA, two RNA strands,
produce DNAproduce DNA