Virology

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Virology

  1. 1. Prepared by Perlie Harriet Mata, RMT
  2. 2. <ul><li>Small size: 0.01 -0.3 um </li></ul><ul><li>FILTERABLE AGENTS </li></ul><ul><li>Virion- viral particle </li></ul><ul><li>Capsid – protects the viral nucleic acid </li></ul>
  3. 3. <ul><li>Virion- the whole viral particle, that is the neocapsid w/ its outer envelope (if present) </li></ul><ul><li>Capsid – protein coat of a virus; made of of numerous capsomere </li></ul><ul><li>Nucleocapsid- the complex of protective protein and viral nucleic acid </li></ul>
  4. 5. <ul><li>They possess only one nucleic acid: </li></ul><ul><li>Either DNA/RNA (NEVER BOTH) </li></ul>
  5. 6. <ul><li>a. Helical- rod shaped </li></ul><ul><li>b. Icosahedra – cube like </li></ul><ul><li>c. complex- non conforming symmetry </li></ul>
  6. 8. <ul><li>1. Type of nucleic acid </li></ul><ul><li>2. Number of strands of nucleic acid and their physical construction (single or double stranded, linear or circular, circular w/ breaks, segmented) </li></ul>
  7. 9. <ul><li>3. Polarity of the viral genome – RNA viruses in w/c the viral genome can be used directly as messenger RNA are by convention termed “positive-stranded” and those for which a transcript has first to be made are termed “negative stranded” </li></ul><ul><li>4. The symmetry of the nucleocapsid </li></ul><ul><li>5. Presence or absence of a lipid envelope </li></ul>
  8. 10. <ul><li>w/o outer membrane – non-enveloped/ naked </li></ul><ul><li>resistant to ether </li></ul><ul><li>ether stable </li></ul><ul><li>w/ outer membrane – enveloped </li></ul><ul><li>sensitive to ether </li></ul><ul><li>ether labile </li></ul><ul><li>labile viruses </li></ul><ul><li>Enveloped – derived from nuclear membrane or host cell </li></ul><ul><li>Composed of Lipid </li></ul><ul><li>Soluble to ether because of thelipid component </li></ul>
  9. 11. <ul><li>I. DNA viruses – replicates in the nucleus </li></ul><ul><li>*dsDNA </li></ul><ul><li>*icosahedral </li></ul>
  10. 12. <ul><li>Parvoviridae – ssDNA </li></ul><ul><li>All are icosahedral symmetry except for Poxviridae – Complex; replicates in the cytoplasm </li></ul><ul><li>Pox viridae – Largest virus complex symmetry </li></ul>
  11. 13. <ul><li>ENVELOPED: Hepadnaviridae, Herpesviridae, Poxviridae </li></ul><ul><li>NAKED: Papovaviridae, Adenoviridae, Parvoviridae </li></ul>
  12. 14. <ul><li>ssRNA except Reoviridae : dsRNA </li></ul><ul><li>Helical except Picornaviridae, Caliciviridae, Reoviridae, Togaviridae, Flaviviridae : Icosahedral </li></ul><ul><li>Enveloped except Picorna, Caliciviridae, reoviridae : Naked </li></ul><ul><li>Replicates in the Cytoplasm except Retroviridae, Orthomyxoviridae : Nucleus </li></ul>
  13. 15. <ul><li>Storage: 4°C </li></ul><ul><li>Transport medium: -70°C </li></ul>
  14. 16. <ul><li>1. Light microscopy </li></ul><ul><li>Viral inclusions </li></ul><ul><li>Negri bodies – inclusion in Rabies virus – cytoplasm </li></ul>
  15. 17. <ul><li>2. Electron Microscopy </li></ul><ul><li>Most rapid way of detecting viral infection </li></ul><ul><li>Most common rapid EM method: Negative staining </li></ul>
  16. 18. <ul><li>3. Culture </li></ul><ul><li>a. Chick embryo </li></ul><ul><li>b. Tissue culture Medium </li></ul><ul><li>A549 cells – lung carcinoma </li></ul><ul><li>HeLa cells – cervical carcinoma </li></ul><ul><li>Hep2 cells – human epithelial cells from laryngeal carcinoma </li></ul><ul><li>Human Fibroblast Cells– preferred tissue culture medium for CMV </li></ul><ul><li>** We do not look for colonies, we look for CHARACTERISTIC CPE </li></ul><ul><li>CPE (cytophatic effect) – morphological change in cells associated w/ viral proliferation </li></ul>
  17. 19. <ul><li>4. SERO Test: </li></ul><ul><li>Neutralization </li></ul><ul><li>Complement fixation test </li></ul><ul><li>Hemagglutination Inhibition (Abs against influenza/ rubella) </li></ul>
  18. 20. BSL1 Non pathogenic for healthy individuals B. subtilis M. gordonae BSL2 Common agents of infectious disease including HIV Either result of bioterrorism/ natural method B. anthracis Y. pestis BSL3 Organism grown in large quantities Culture for MTB Systemic Fungi (Mold form) Francisella tularensis Brucella spp. BSL4 Arboviridae Arenaviridae Filovirus (Ebola virus) Small pox (last case 1997)
  19. 21. <ul><li>Virus Family </li></ul>
  20. 22. <ul><li>Arthropod – borne viruses </li></ul><ul><li>1. Bunyaviridae </li></ul><ul><li>2. Flaviviridae </li></ul><ul><li>3. Togaviridae </li></ul>
  21. 23. <ul><li>EBV: </li></ul><ul><li>Infectious mononucleosis </li></ul><ul><li>Burkitt’s lymphoma </li></ul><ul><li>Target cell: B cells (CD21) </li></ul><ul><li>IM: Atypical/ Reactive lymphocytes (Downey cells) </li></ul><ul><li>T cells reacting to B cells infected w/ EBV </li></ul>
  22. 24. <ul><li>infections </li></ul><ul><li>Toxoplasmosis </li></ul><ul><li>Rubella </li></ul><ul><li>CMV </li></ul><ul><li>Herpes </li></ul><ul><li>Syphilis </li></ul>
  23. 25. <ul><li>CMV: most common congenital infection </li></ul><ul><li>Blood Transfusion (leukocytes)/ organ transplant </li></ul><ul><li>CMV aka Salivary Gland Virus </li></ul><ul><li>> 40 day fever </li></ul><ul><li>Culture: human fibroblast cells </li></ul><ul><li>Inclusion: OWL’s eye inclusion </li></ul>
  24. 26. <ul><li>HHV6 and HHV7: Roseola (Exanthem subitum) </li></ul><ul><li>6 th childhood disease </li></ul><ul><li>HHV8: Kaposi’s sarcoma </li></ul><ul><li>Most common malignancy observed among AIDS patients </li></ul>
  25. 27. <ul><li>Pa = papilloma virus : WART’s </li></ul><ul><li>Po = Polyomavirus </li></ul><ul><li>Va –vacuolating virus of monkey </li></ul>
  26. 28. <ul><li>Parvovirus B-19 </li></ul><ul><li>Slapped cheek Rash </li></ul><ul><li>Erythema infection </li></ul><ul><li>5 th disease </li></ul>
  27. 29. <ul><li>Guarheiri body </li></ul><ul><li>Vaccinia – cow pox virus </li></ul><ul><li>Variola major – small pox </li></ul><ul><li>Variola minor – Alastrim </li></ul>
  28. 30. <ul><li>Caliciviridae: </li></ul><ul><li>Hepa E- fecal oral route </li></ul><ul><li>Water contamination </li></ul><ul><li>Increased fatality : pregnancy </li></ul>
  29. 31. <ul><li>Coronaviridae – common colds </li></ul><ul><li>SARS </li></ul>
  30. 32. <ul><li>Yellow viruses </li></ul><ul><li>**Dengue </li></ul><ul><li>Hepa C – most common cause of post transfusion Hepatitis </li></ul><ul><li>Hepa C 80% </li></ul><ul><li>Hepa B <10% </li></ul>
  31. 33. <ul><li>Orthomyxoviridae: Genus influenza </li></ul><ul><li>Enveloped have spikes </li></ul><ul><li>Composition of spikes: hemagglutinin Ag </li></ul><ul><li>Neuramidase </li></ul><ul><li>Infected cell is identified by HEMADSORPTION </li></ul><ul><li>Abs: Hemagglutination inhibition </li></ul>
  32. 34. <ul><li>a. Measles – rubeola </li></ul><ul><li>b. mumps </li></ul><ul><li>c. Parainfluenza </li></ul><ul><li>d. RSV – respiratory syncytial virus </li></ul>
  33. 35. <ul><li>Smallest RNA virus </li></ul>
  34. 36. <ul><li>Hepa A virus: genus enterovirus type 72 </li></ul><ul><li>Short incubation heap </li></ul><ul><li>15-40 days incubation period </li></ul><ul><li>  </li></ul><ul><li>Differentiate </li></ul><ul><li>Enterovirus: Acid resistant </li></ul><ul><li>Rhinovirus: Acid Sensitive </li></ul>
  35. 37. <ul><li>children: gastritis/ diarrhea </li></ul><ul><li>adults: asymptomatic </li></ul><ul><li>*common cause of gastritis and diarrhea in winter </li></ul>
  36. 38. <ul><li>Reverse trancscriptase: unique enzyme </li></ul><ul><li>RNA-> DNA </li></ul><ul><li>Genus: Lentivirus </li></ul><ul><li>HIV1: AIDS in US and Europe </li></ul><ul><li>HIV2: AIDS in west Aftrica </li></ul><ul><li>Target cell CD4+ </li></ul>
  37. 39. <ul><li>HTLV I </li></ul><ul><li>HTLVII – associated with hairy cell leukemia </li></ul>
  38. 40. <ul><li>– Bullet shaped </li></ul><ul><li>Rabies/ Lyssa virus </li></ul>
  39. 41. <ul><li>Rubella – German </li></ul><ul><li>Measles </li></ul><ul><li>Aka RUBIVIRUS </li></ul>
  40. 42. <ul><li>Pox viridae – Largest virus complex symmetry </li></ul><ul><li>Picornavirus - Smallest RNA virus </li></ul>

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