VIrology Mcqs Remain

10 clinical MCQs in Medical Virology. Which is the BEST order of the stages of viral pathogenesis?. Kenya, Africa and global revision.

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.