MCQ IN MEDICINE

Detailed explanation-1: -As a virus replicates, its genes undergo random “copying errors” (i.e. genetic mutations). Over time, these genetic copying errors can, among other changes to the virus, lead to alterations in the virus’ surface proteins or antigens. Our immune system uses these antigens to recognize and fight the virus.

Detailed explanation-2: -The more a virus circulates in a population of people, the more it can change. All viruses mutate but not always at the same rate. “The rate of change varies from virus to virus.

Detailed explanation-3: -RNA viruses are characterized by high mutation rates compared with most DNA systems (1), due mainly to the lack of exonuclease proofreading activity displayed by their RNA polymerases (2).

Detailed explanation-4: -Rates of spontaneous mutation vary amply among viruses. RNA viruses mutate faster than DNA viruses, single-stranded viruses mutate faster than double-strand virus, and genome size appears to correlate negatively with mutation rate.