Antigenic Drift

Antigenic Drift

Subject : Science & tech

Concept :

Background

• In India, it was known as the Bombay Fever that broke out in the city in June 1918, with one of the possible entry points being ships carrying troops returning from the First World War in Europe. It hit different parts of the country in three waves, with the second recording the highest fatality rate.
• The pandemic is believed to have killed 17-18 million people in the country. By early 1919, it had largely disappeared.
• It is argued that since the whole world had been exposed to the virus, and had therefore developed natural immunity against it, the 1918 strain began to mutate and evolve in a process called “antigenic drift”.

Antigenic Drift

• Antigenic drift is a kind of genetic variation in viruses, arising by the accumulation of mutations in the virus genes that code for virus-surface proteins that host antibodies recognize.
• This results in a new strain of virus particles that is not effectively inhibited by the antibodies that prevented infection by previous strains.
• This makes it easier for the changed virus to spread throughout a partially immune population. Antigenic drift occurs in both influenza A and influenza B viruses.
• Antigenic shift is a closely related process; it refers to more dramatic changes in the virus’s surface proteins. Genetic drift is very different and much more broadly applicable; it refers to the gradual accumulation in any DNA sequence of random mutational changes that do not interfere with the DNA’s function and thus that are not seen by natural selection.