GATE 2022 BT – Question 52
Emerging viruses such as SARS-CoV2 cause epidemics. Which of the following process(es) contribute to the rise of such viruses?
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Correct answer: (A) Mutation of existing virus; (B) Jumping of existing virus from current to new hosts; (C) Spread of virus in the new host population
Explanation
**Emerging viruses** appear when a virus gains the ability to infect and spread in a new population.
- **A. Mutation of an existing virus.** Mutations can create variants that infect new hosts or spread more efficiently. ✓
- **B. Jumping from current to new hosts** (zoonotic spillover). A virus crosses from animals to humans, as SARS-CoV-2 did. ✓
- **C. Spread in the new host population.** Sustained transmission among the new hosts turns a spillover into an epidemic. ✓
- **D. Replication outside a host.** False. Viruses are obligate intracellular parasites and cannot replicate outside host cells. ✗
Answer **A, B and C**.