Question

Emerging viruses such as SARS-CoV2 cause epidemics. Which of the following process(es) contribute to the rise of such viruses?

• A. Mutation of existing virus
• B. Jumping of existing virus from current to new hosts
• C. Spread of virus in the new host population
• D. Replication of virus outside a host

Hint:

Emerging viruses usually arise through mutation, host switching, and rapid spread—never through replication outside a host.

Answer 1

The Correct Option is A, B, C

Emerging viruses arise due to several evolutionary and ecological processes.
Option A: Mutation of existing virus
Viruses, especially RNA viruses such as coronaviruses, mutate rapidly due to error-prone replication.
These mutations can give rise to variants with improved infectivity or host range. Hence, A is correct.
Option B: Jumping of viruses to new hosts (spillover)
When a virus moves from its original host species to a new host species (e.g., bat → human), it is called spillover.
This is a major mechanism behind emerging diseases such as SARS, MERS, and COVID-19. Hence, B is correct.
Option C: Spread within the new host population
After entering a new host species, extensive transmission within that population allows the virus to establish itself and expand.
Thus, this also contributes to emergence and outbreaks. Hence, C is correct.
Option D: Replication of virus outside a host
Viruses are obligate intracellular parasites and cannot replicate outside a living cell.
Therefore, D is incorrect.
Thus, the correct processes are A, B and C.