Explain the difference between antigenic drift and antigenic shift in the influenza virus
What will be an ideal response?
Antigenic drift is due to the frequent point mutations in the RNA genome of influenza virus. Mutants that acquire changes in the HA and NA epitopes are selected because they are not subject to the serotype-specific immunity generated against the original strain. Because point mutation causes only relatively small changes at a time, this process is known as antigenic drift.
Antigenic shift is due to recombination between a human influenza virus and an avian influenza virus, leading to replacement of the human NA and/or HA with the avian type. The genome of the influenza virus is composed of eight separate pieces of RNA. When a human influenza virus and an avian influenza virus infect the same cell (usually in domestic livestock such as pigs, ducks, or chickens), reassortment of the RNAs can lead to the generation of a new human virus encoding the avian HA and/or NA that has never before been encountered by the human population.
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