VIrology Mcqs Remain

10 clinical MCQs in Medical Virology. Which is the BEST order of the stages of viral pathogenesis?

Questions, Answers & Explanations

1. Q1. Which is the BEST order of the stages of viral pathogenesis?

   • Viral entry → primary replication → viremia → replication within target organs
   • Viral entry → primary replication → replication within target organs → viremia
   • Primary replication → viral entry → viremia → replication within target organs
   • Viral entry → replication within target organs → viremia → primary replication

   Answer: Viral entry → primary replication → viremia → replication within target organs

   Explanation: Viruses enter, replicate locally first, then spread via bloodstream (viremia) to reach and replicate in target organs.

2. Q2. One of the following is NOT CORRECT about Influenza A Virus:

   • May undergo antigenic shift and antigenic drift
   • Vaccination confers lifelong protection
   • May cause pandemics
   • Respond to rimantadine

   Answer: Vaccination confers lifelong protection

   Explanation: Influenza constantly mutates via antigenic drift/shift, so annual vaccination is needed. No lifelong protection exists.

3. Q3. Choose MOST CORRECT: Viruses which cause persistent infections...

   • Can establish persistence only in persons with defective immunity
   • Are all capable of destroying CD4+ T-helper cells
   • Have evolved mechanisms for escaping detection/clearance by host immune system
   • Are all able to cause persistent infection within cells not expressing Class I MHC antigens

   Answer: Have evolved mechanisms for escaping detection/clearance by host immune system

   Explanation: Persistent viruses like HSV, CMV, HIV have evolved specific strategies to evade immune detection — not limited to immunocompromised hosts.

4. Q4. Which is NOT an important factor in viral interaction with the respiratory tract?

   • Mucociliary transport
   • Relatively low temperature of upper airways
   • Mucosal IgA production
   • M cells

   Answer: M cells

   Explanation: M cells are located in gut-associated lymphoid tissue (Peyer's patches), not the respiratory tract. All others are key respiratory defense factors.

5. Q5. Which virus has capacity to spread to CNS by passage along nerve fibers?

   • Herpes simplex virus
   • Poliovirus
   • HIV-1
   • Measles virus

   Answer: Herpes simplex virus

   Explanation: HSV travels retrograde along sensory nerve axons to reach dorsal root ganglia and CNS. This is called neural/axonal spread.

6. Q6. Which host defense is LEAST likely important during EARLY stages of viral infection?

   • Mucociliary transport system
   • Interferon alpha and beta
   • Natural killer cells
   • Virus-specific cytotoxic lymphocytes

   Answer: Virus-specific cytotoxic lymphocytes

   Explanation: CTLs are adaptive immune cells requiring days to develop and activate. Early infection relies on innate immunity — interferons, NK cells, macrophages.

7. Q7. What is the body's target site for the paramyxovirus that causes mumps?

   • Throat
   • Mouth
   • Parotid gland
   • Adenoid glands

   Answer: Parotid gland

   Explanation: Mumps virus specifically targets the parotid salivary glands, causing the characteristic swollen jaw/cheeks (parotitis). Can also affect testes, ovaries, pancreas.

8. Q8. What virus can cause teratogenic effects?

   • SARS
   • Influenza
   • Hanta
   • Rubella (Rubivirus)

   Answer: Rubella (Rubivirus)

   Explanation: Rubella is the classic teratogenic virus — causes congenital rubella syndrome with cataracts, cardiac defects, deafness, and intellectual disability when infection occurs in first trimester.

9. Q9. Poliovirus has an affinity for what body system?

   • Gastrointestinal system
   • Nervous system
   • Genitourinary system
   • Circulatory system

   Answer: Nervous system

   Explanation: Poliovirus enters via GIT but its main target is anterior horn motor neurons of the spinal cord, causing flaccid paralysis.

10. Q10. Which statement TRUE regarding cell cultures?

    • Viruses can only be cultured using cell lines
    • Presence of cytopathic effect is the only way to detect a virus
    • The neutralization test is the mainstay of identification of a poliovirus isolate
    • The haemagglutination inhibition test is the mainstay of identification of RSV isolate

    Answer: The neutralization test is the mainstay of identification of a poliovirus isolate

    Explanation: Neutralization test uses specific antibodies to confirm poliovirus type. Cytopathic effect alone is not specific enough for identification.