Viruses 2 Flashcards
List 4 routes of viral entry with examples.
-Respiratory (Influenza)
-Fecal-oral (Polio)
-Skin- (HSV via cold sores)
-Urinogenital (HIV, HPV)
Why is polio primarily transmitted via the fecal-oral route?
Virus replicates in gut → shed in feces → contaminates water/food.
Define pathogenesis in virology.
Virus-induced disease mechanisms (e.g., direct cell lysis or immune-mediated damage).
Contrast innate vs. adaptive immunity to viruses.
-Innate: Fast, nonspecific (IFNs, NK cells).
-Adaptive: Slow, specific (antibodies, CTLs).
How do TLRs bridge innate and adaptive immunity?
Recognize viral PAMPs (e.g., dsRNA) → activate dendritic cells → prime T-cells.
Why are 90% of polio infections asymptomatic?
Immune response controls virus before CNS invasion.
What causes paralysis in polio?
Virus crosses blood-brain barrier → destroys motor neurons.
Explain antigenic drift vs. shift.
-Drift: Minor mutations (seasonal epidemics).
-Shift: Reassortment (pandemics, e.g., 1918 H1N1).
Why did H5N1 avian flu have high mortality but poor human transmission?
Binds α2-3 sialic acid (deep lungs) → severe pneumonia but not easily coughed out.
How does HSV establish latency?
Hides in sensory ganglia (low MHC-I) → reactivates under stress.
Why does HIV target CD4+ T-cells?
CD4 is viral receptor; cell death → immunosuppression → AIDS.
How do HPV E6/E7 proteins cause cancer?
E6 degrades p53; E7 inactivates Rb → unchecked cell division.
What is HAART’s mechanism?
inhibits reverse transcriptase, protease, integrase to suppress viral load.
Which HPV strains does the vaccine target?
Oncogenic types (16/18) and wart-causing types (6/11).
How does HIV evade CTLs?
Rapid mutation → escape variants (e.g., TW10 epitope in HLA-B57).
What is lysis from without in phage therapy?
Phage overload → bacterial death without replication.
