Module 10a   virology
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  • 1. Choose me !!!!!! VirologyMorphology & Background Common viruses Viral Diseases
  • 2. Background Information:)s virus are parasites, s all cells can be not cells parasitized bys virus are packages virus, they only of genetic info - attack closely nucleic acids in related organisms protein coats s virus comes from as virus only supplies latin word “poison” information, rest is or “slime” dependent on host
  • 3. What are viruses? s virus = “poison”s with genetic material (DNA or RNA) and protein coat (capsid).s obligatory intracellular parasites.s infect the cells of a biological organisms.s they replicate by using the host cell’s metabolic“machinery”.
  • 4. Definition of Terms: s Capsid- protein shell, or coat, that encloses the nucleic acid genomes Capsomere – Morphologic units of virus seen under the EM on the surface of icosahedral virus particles • Represents clusters of polypeptides Defective virus – virus particle that is functionally deficient in some aspect of replication
  • 5. More terms: s Envelope – lipid containing membrane that surrounds some virus particles • Acquired during viral maturation by a budding process thru a cellular membranes Nucleocapsid – protein nucleic acid complex representing the packaged form of the viral genomes Subunit – single folded viral polypeptide chain
  • 6. s Structural units – Basic protein building blocks of the coat. • Usually a collection of more than one nonidentical protein unit. • The structural unit is often referred to a protomer.s Virion – Complete virus particle. In some instances, the virion is identical to the nucleocapsid. In more complex virions, this includes the nucleocapsid plus a surrounding envelope.
  • 7. Background Information: s Dmitri Iwanowski - s Are viruses alive?? 1892 first isolation they contain of TMV macromoleculess Martinus Beijerinck but does not - filterable viruses reproduce directlys Wendell Stanley - --- virions are intact, non- 1935 purified & replicating virus crystallized TMV particles ( no life)
  • 8. Basis of classifications Virus morphology s Virus genome • Size properties • Shape • Nucleic Acid ( DNA • Type of symmetry or RNA ) • Presence & absence • Size of genomes in of peplomers kb (kilobase pairs ) • Presence & absence • Strandedness (single of membranes or double ) • Nucleotide sequence
  • 9. Basis for Classification:s Host Range s Size • Plant virus • 25 nm to 300 nm • Animal Virus • 1/10 to 1/3 of • Bacteriophage bacteria • no cytoplasmic • Specificity cultivars structures ( plants), race or • can be 77 genes strains, receptors or 3 genes but (protein) still very lethal
  • 10. SIZEs Most viruses with capsid = between 10-300 nm
  • 11. Structure:s Nucleic Acid core surrounded by proteins Viral Envelope - naked or envelopeds Nucleic Acid - DNA or RNA
  • 12. s Genome organization & replication s Antigenic properties • Gene order • Gene number s Biologic properties • Position of open including : reading frames • Natural host range • Patterns of • Mode of replication transmission • Cellular sites • Vector relationship • Pathogenecity • Tissue tropisms • Pathology
  • 13. s Physiochemical s Virus protein Properties of the properties virion • Number • Molecular mass • Size • Buoyant density • Functional activities • pH stability • Amino acid • Thermal stability sequence • Susceptibility to agents • Modifications & – Ethers special functions – Detergents – Transcriptase – Reverse trans. – Neuramidase – fusion
  • 14. Types of Structures Four morphological types: • 1. Helical Viruses • 2. Icosahedral viruses • 3. Enveloped viruses • 4. Complex viruses
  • 15. Helical virus -Resemble long rods, may be rigid or flexible -Viral nucleic acid found within a hollow cylindrical capsid. -with single type of protomers stacked around a central axis to form a tube; eg. Tobacco mosaic virus.
  • 16. Icosahedralspherical appearancebut capsomeresarranged in ageometrical pattern likea soccer ball;eg.hepatitis B
  • 17. Enveloped with outer lipid layer = viral envelope
  • 18. Complex -- with extra structure such as protein tails, complex outer walls; eg. Bacteriophages, Poxviruses.
  • 19. Life Cycle:s outside the host there is no replications Stages : • -->Adsorption • --> Penetration • --> Uncoating • --> Viral synthesis • --> Maturation • --> Release
  • 20. Multiplication of Virusess Lytic cycle – ends with the lysis and death of the host cell.s Lysogenic cycle- host cell remains alive
  • 21. Taxonomy:s ICTV - International Committee on Taxonomy of Viruss Family Name -- Viridae -- Retroviridaes Genus -- Virus -- Lentiviruss Specie -- English -- HIVs Hepadnaviridae -- 7 DNA - Hepatitis
  • 22. Misc. Information:s Replication applicable to all viruss Plaque count - PFU Plaque forming unitss One Step Growth Phase -- Latent ---> Burst Period
  • 23. Common viruses in animals:s Line 1 - Familys Line 2 - Classification based on N.A.s Line 3 - Propertiess Line 4 - Virus (species or Genus)s Line 5 - Diseases *** Legend
  • 24. s Herpesviridaes DNA viruss Enveloped dsDNAs Herpes simplex 1&2, Varicella zoster, EBV, cytomegalovirus CMVs cold sores, genital herpes, shingles, mononucleosis, birth defects
  • 25. s Poxviridaes DNA viruss Enveloped dsDNAs Smallpox viruss Smallpox ( variola )
  • 26. s Hepadnaviridaes DNA viruss Enveloped dsDNAs Hepatitis B viruss Hepatitis B
  • 27. New Nomenclature forHepatitis Viruss Hepatitis A • HAV virus • Etiologic agent of infectious Hepatitis • A picornavirus, the prototype of a new genus, Hepatovirus • Anti-HAV – antibody to HAV. Detectable at onset of symptoms; lifetime persistence • IgM antibody
  • 28. Hepatitis B s Antibodies for Hep Bs HBV- Hepatitis B • Anti-HBs virus • Anti-HBes Etiologic agent of • Anti-HBc serum hepatitiss A hepadnavirus • IgM class Antibodys HBsAg, HBeAg, HBcAg
  • 29. Hepatitis Cs HCV – Hepatitis C Viruss A common etiologic agent of post transfusion hepatitiss A Flavivirus, genus Hepaciviruss Anti-HCV – antibody to HCV
  • 30. Hepatitis Ds Hepatitis D Viruss Etiologic agent of delta hepatitiss Causes infection only in presence of HBVs HDAg – Delta antigen, detectable only in early acute HDV infections Anti-HDV - Antibody
  • 31. Hepatitis Es HEV – Hepatitis E Viruss Enterically transmitted hepatitis viruss Causes large epidemics in Asia, North & West Africa and Mexicos Fecal-oral or waterborne infections Unclassified
  • 32. s Papoviridaes DNA viruss naked dsDNAs Human papillomavirusess Warts
  • 33. Polyomavirusess Small (45nm ) naked, heat stable, ether resistant viruss Cubic symmetry with 72 capsomeress Circular, double stranded DNAs JC virus, BK virus, SV40 viruss Formerly part of Papoviridae family
  • 34. s Adenoviridaes DNA viruss Naked dsDNAs Human adenoviruss respiratory, enteric diseases, infectious pinkeye
  • 35. Parvoviruss Naked Single stranded DNA viruss Cubic symmetry with 32 capsomeress 5.6 kb in sizes Requires the presence of adenovirus or herpesvirus as helper ( defective )
  • 36. s Retroviridaes RNA viruss Enveloped + strand RNAs HIV-1 & 2, HTLV-1 &2s AIDS , T cell leukemia
  • 37. Life Cycle of HIV Virus
  • 38. Astrovirusess 28-30 nm in diameters Exhibit a distinctive star-like morphology under the EMs Ss + sense RNA, 6.4 – 7.4 kb in sizes Causes diarrheal illnessess Transmitted by fecal-oral route thru contaminated food or water
  • 39. Arboviruses (arthropod borne)s Arenaviridaes Bunyaviridaes Flaviviridaes Filoviridaes Reoviridaes Togaviridae
  • 40. Arenavirusess Generally associated with rodent- transmitted disease in humans.s Each virus usually is associated with a particular rodent host species in which it is maintaineds Divided into two groups: • the New World or Tacaribe complex • the Old World or LCM/Lassa complex.
  • 41. Filoviruses
  • 42. s Flaviviridaes RNA viruss enveloped + strand RNAs Yellow & Dengue fever , Hep C viruss Yellow & Dengue fever, Hepatitis C
  • 43. Prevention of Dengue
  • 44. Types of Dengues Non-fatal dengue fever (DF)s Fatal Dengue Hemorrhagic fever (DHF)s Dengue Shock Syndrome ( DSS)
  • 45. Serotypes of Dengues 4 serotypess DEN-1, DEN-2, DEN-3, DEN-4s DEN-2 shows greatest antigenic and genotypic distance from the otherss Protective immunity after infection is homotypic(Which means if your really unlucky u can have dengue __ times.) 
  • 46. More types of Flaviviruss Eastern & Western Encephalitiss St. Louis Encephalitiss West Nile Fevers Japanese B Encephalitiss Yellow Fever
  • 47. s Reoviridaes RNA viruss naked dsRNAs Rotaviruss Infant diarrhea
  • 48. s Bunyaviridaes RNA viruss Enveloped - strand RNAs Hantaviruss Respiratory distress syndrome
  • 49. s Togaviridaes RNA viruss Enveloped + strand RNAs Alphavirus, Rubella viruss encephalitis, Rubella (German measles)
  • 50. Picornavirusess Enterovirus s Rhinovirus • Transient inhabitants • Isolated chiefly from of the human the throat and nose alimentary tract • More than 100 • Poliovirus species based on • Coxsackie virus receptors – ICAM -1 • Paraechovirus – LDLR – Echovirus 22 – Echovirus 23
  • 51. s Picornaviridaes RNA viruss Naked + strand RNAs Enterovirus, Poliovirus, echovirus, Rhinovirus, hepatitis A viruss Polio, Myocarditis, pericarditis, colds, Hepatitis A
  • 52. s Coronaviridaes RNA viruss Enveloped + strand RNAs Coronaviruss upper respiratory tract infections
  • 53. s Calciviridaes RNA viruss naked + strand RNAs Norwalk Agentss Gastroenteritis
  • 54. s Orthomyxoviridaes RNA viruss Enveloped - strand RNAs Influenza viruss Influenza
  • 55. s Rhabdoviridaes RNA viruss enveloped - strand RNAs Rabies viruss Rabies
  • 56. s Paramyxoviridaes RNA viruss enveloped - strand RNAs Mumps, measles virus, Parainfluenza virus, Respiratory syncitial vir.s mumps, rubeola, Croup, Bronchiolitis
  • 57. Recent Viral Diseasess SARS- severe acute respiratory syndrome
  • 58. Avian Flu- spread of H5N1 strain
  • 59. Influenza Pandemic(1918-1919) – TEM of Spanish Influenza Virus (negatively-stained); subtype H1N1; H2N2; H3N2 25 million deaths in 25 weeks 20% of world population affected. 1957-1958 1968-1969 Next pandemic ????
  • 60. Virus entry into an animal cell
  • 61. What other roles could beattributed to viruses other thanbeing pathogens?s Basic research, molecular biology and biotechnologys Horticultures Cross- protections Gene therapys Phage therapys Viro-therapy
  • 62. Continuation……..s Material Science and Nanotechnology- In April 2006, MIT scientists created nanoscale metallic wires using a genetically-modified virus. The MIT team was able to use the virus to create a working battery with an energy density up to three times more than current materials. The potential exists for this technology to be used in liquid crystals, solar cells, fuel cells, and other electronics in the future.s Biological warfare- synthesis/recreation of viruses in laboratory (eg. 1918 flu virus, smallpox virus- Variola major)