Virus stuff

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Virus stuff
2014-11-13 18:15:07
virus stuff fdn3 virology tubberly

Just stuff about stuff
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  1. What is a virus
    • Packaged set of genes inert outside of cells
    • Require cells for protein, nucleic acid synthesis, and energy
  2. Virion
    • viral structure
    • 20nm to 1 ┬Ám
    • helix or icosahedron with few exceptions
    • can be enveloped
    • DNA or RNA, ds ss, + -
    • DNA can be circular
    • RNA can be segmented
  3. Susceptible cells
    • have receptors for virus
    • can be productively infected
    • abortively infected
    • latently infected (maintaining viral genome)
    • non-permissive
  4. Attachment to cell
    • protein receptor interaction
    • electrostatic
  5. Penetration of cell
    • sometimes receptor binding brings membranes close enough for fusion
    • more commonly the binding recruits other receptors to form a coated pit vesicle
    • lysosome fuses with phagosome and pH releases virus from vesicle
  6. Eclipse period
    time between viral adsorption and rise in intracellular viral concentration
  7. Latent period
    • time between viral adsorption and rise in extracellular viral concentration
    • latent infections are usually through DNA
    • no viral genome replication (except with cell division)
    • few if any viral proteins expressed (non-immunogenic)
    • compatible with cell survival
  8. ds DNA
    • adenoviruses and herpesviruses
    • virus DNA replicated to make progeny DNA as well as transcribed to mRNA
    • mRNA makes immediate early proteins, early proteins, and then late proteins
    • early proteins make viral proteins and late make capsule
    • drugs can target transcription, replication, assembly
  9. Release from cell
    • capsid can associate with membrane protein viral protein spikes, causing them to gather and bud
    • usually lyse the cell
  10. Arboviruses
    • bug borne
    • eveloped RNA
    • lots of them
    • rapid onset fever, chills, aching
  11. Enteroviruses
    • all start oral and go to stomach
    • infects GI
    • usually self limiting
    • includes polio
    • hand-foot-mouth disease
  12. Plaque Assay
    • can detect viruses, titer them, and isolate
    • dilution series and then plate onto cells
  13. Salk Vaccine
    • IPV, killed
    • imperfect
  14. Sabin Vaccine
    OPV, live attenuated from chimps
  15. Accute infection
    • Viral production increases with symptoms at peak
    • After a short time the viral production decreases as do symptoms
    • rhinovirus, rotavirus, influenze virus
  16. Persistent infection
    • Viral production increases to high plateau without symptoms
    • after a long time of sustained viral production symptoms appear
    • lymphocytic chroiomeningitis virus, HBV, HCV
  17. Latent, reactivating infection
    • Viral production increases and decreases over time
    • Symptoms may or may not show depending on to what level the viral production reaches
    • Herpex simplex virus
  18. Slow virus infection
    • Initial viral production increase with symptoms at peak
    • after a short time the viral production drops and levels off at a low level with no symptoms
    • after a long time the viral production increases again, symptoms reappear and death often occurs
    • measles subacute sclerosing panenchephalitis (SSPE), HIV
  19. Herpes classification
    • classes I, II, and III are associated with different groups of animals
    • class I is mammals (humans), reptiles and birds
    • class II amphibians and fish
    • class III bivalves
    • within class I is alpha beta and gamma
    • in humans alpha is always neuroinvasive with a short reproduction cycle HSV1, HSV2, VZV
    • beta is cytomegalovirus mainly with long reproduction cycle CMV, HHV6, HHV7
    • gamma is lymphotropic, oncogenic. EBV, KSHV
  20. Primary host v secondary host
    • primary host maintains the virus in nature with mild/benign infections
    • secondary host is a dead end host, causing a fatal infection
  21. Acyclovir
    • related to valavyvlocir and gancyclovir
    • GTP analog missing 2 and 3 positions of ribosome and phosphates
    • cannot polymerize
    • herpes thymidine kinase of herpes virus adds a phosphate
    • cellular kinases continue adding kinases to make acycloguanosine-PPP
    • does not work on TK mutant viruses of immunocompromised people
  22. Virally transformed cell characteristics
    • itnegrated or episomal DNA sequences
    • indefinite in vitro growth potential
    • higher cloning efficiency
    • anchorage independence
    • chromosomal abnormalities
    • virally expressed tumor antigens
  23. Gardasil
    • inactivated fractional
    • HPV 6, 11, 16, 18
    • no effect on existing infection
    • super effective (for specific types) with no known harmful effects
    • not effective against ~30% of infections that can lead to cervical cancer
    • expensive and social drama
  24. Pap smear
    • looks for cells with aberrant morphology, koilocytes
    • nucleus pushed to side (good sensitivity, not specific)
    • further testing required to confirm cancer