Which virus, once acquired, persists in the host for life?

Correct answer: C. Herpes simplex virus

• A. Rhinoviruses cause the common cold and are cleared completely by the immune response; recurrent colds are new infections with different serotypes, not reactivation.
• B. Hepatitis A causes an acute, self-limited, faecal-orally transmitted infection with no carrier state and no chronic phase — unlike hepatitis B and C.
• C. CORRECT. HERPES SIMPLEX VIRUS establishes lifelong LATENCY. After primary infection, the virus travels retrograde along sensory axons to the TRIGEMINAL GANGLION, where its genome persists as an episome with minimal gene expression and remains beyond the reach of both the immune system and antiviral drugs. Reactivation, triggered by ultraviolet light, fever, stress, trauma or immunosuppression, sends virus back down the axon to produce recurrent herpes labialis or intraoral recurrences on keratinised mucosa. All herpesviruses share this property — VZV latent in dorsal root and cranial ganglia, EBV in B lymphocytes, CMV in monocytes.
• D. Influenza A is cleared after acute infection. Reinfection reflects ANTIGENIC DRIFT and SHIFT producing new variants, not persistence of the original virus.

Note: That is a technically accurate distinction but not the standard exam answer. The examinable fact is that herpesviruses establish lifelong latency and can reactivate at any time.