# DBT JRF 2022 — Question 55

Exam: DBT JRF 2022 · Section: B · Topic: Microbiology › Virology - Viral Latency · Difficulty: Medium

## Question

Latency is a characteristic of which one of the following viruses?

## Options

- **A.** Herpes virus
- **B.** Polio virus
- **C.** Rhino virus
- **D.** Influenza virus

## Answer

Option A

## Explanation

Herpesviruses and neuronal latency: Herpesviruses establish LIFELONG LATENT INFECTIONS in neurons: • HSV-1 (Herpes Simplex Virus 1): Latency in trigeminal ganglia; reactivation causes cold sores. • HSV-2: Latency in sacral ganglia; reactivation causes genital herpes. • VZV (Varicella-Zoster Virus): Primary infection = chickenpox; latency in dorsal root/cranial ganglia; reactivation = shingles (herpes zoster). Mechanism: During latency, only LATs (Latency-Associated Transcripts) are expressed; no viral proteins → immune evasion. Reactivation triggers: stress, UV light, fever, immunosuppression. Viruses that do NOT establish neuronal latency: • Poliovirus (Picornaviridae): causes acute infection/lytic cycle. • Rhinovirus: causes common cold; acute infection. • Influenza virus: causes acute respiratory infection; no latency. Answer: Herpes viruses (HSV-1, HSV-2, VZV) establish lifelong latency in neurons.

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