Viral Pathogenesis Flashcards
7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Viral Pathogenesis flashcards as text
Why are pregnant women at higher risk for severe outcomes from certain viral infections such as influenza?
Answer: Pregnancy increases susceptibility because the immune system is partially suppressed to tolerate the fetus
Immune tolerance adaptations during pregnancy reduce Th1-mediated responses, impairing antiviral immunity and increasing risk of severe viral disease.
What is antigenic drift in influenza virus, and what is its clinical significance?
Answer: Gradual accumulation of point mutations in surface antigens reducing vaccine effectiveness
Antigenic drift involves gradual mutation of hemagglutinin and neuraminidase genes, allowing influenza to escape pre-existing immunity and necessitating annual vaccine reformulation.
How does rabies virus travel from the site of a bite wound to the central nervous system?
Answer: By retrograde axonal transport along peripheral nerves
Rabies virus binds to nicotinic acetylcholine receptors at neuromuscular junctions and travels to the CNS via retrograde axonal transport within peripheral nerve fibers.
Which of the following best describes the concept of 'viral fitness'?
Answer: The virus's ability to replicate and transmit successfully in a given host environment
Viral fitness refers to the relative ability of a viral strain to replicate and be transmitted within a host population compared to competing strains.
In what way does dengue virus immune enhancement lead to more severe disease upon secondary infection?
Answer: Sub-neutralizing antibodies from prior infection facilitate uptake of new serotype into Fc receptor-bearing monocytes
Antibody-dependent enhancement (ADE) occurs when non-neutralizing antibodies from a prior dengue infection opsonize a different serotype, increasing viral uptake into monocytes and amplifying viral load.
What is the significance of the 'incubation period' in the epidemiology of viral diseases?
Answer: It is the time between exposure and symptom onset, during which transmission may silently occur
During the incubation period, the virus replicates but symptoms have not yet appeared; many viruses are transmissible during this phase, facilitating silent spread in populations.
How does hepatitis B virus (HBV) cause chronic liver disease rather than resolving like most viral infections?
Answer: HBV evades immune clearance and persists, causing ongoing immune-mediated liver inflammation
HBV evades complete immune clearance in some individuals; persistent infection leads to chronic hepatitis driven by CD8+ T cell-mediated destruction of infected hepatocytes over decades.