EVERYDAY SCIENCE

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: -As you have learned, viruses typically mutate more rapidly than human cells do. This is because human cells have mechanisms to proofread the genome and also mechanisms to repair a sequence if an error is detected.

Detailed explanation-3: -The RNA polymerase that copies the virus’s genes generally lacks proofreading skills, which makes RNA viruses prone to high mutation rates-up to a million times greater than the DNA-containing cells of their hosts.

Detailed explanation-4: -What is the advantage of constantly changing viral surface protein? The host has no pre-existing immunity, in the form of antibodies, to that virus.