What is antigenic drift and how does it benefit viruses?

Answer 1

Antigenic drift is the gradual accumulation of mutations in the genes that encode viral surface proteins, such as hemagglutinin (HA) in influenza viruses, leading to changes in the antigenic properties of the virus. These antigenic changes enable the virus to evade the immune system and cause recurrent infections in individuals who have previously been exposed to the virus or vaccinated against it.

Antigenic drift benefits viruses by allowing them to escape recognition and neutralization by the host immune response, thereby increasing their survival and replication in the host population. It also enables viruses to spread globally and cause seasonal outbreaks or pandemics, as the immune system of the population gradually loses the ability to recognize and control the virus due to its antigenic changes. This is particularly evident in influenza viruses, which undergo frequent antigenic drift and require annual updates of the vaccine to match the predominant circulating strains.