A sudden shift in the antigenicity of a virus resulting from the recombination of the genomes of two viral strains. Antigenic shift is seen only with influenza A viruses. It results usually from the replacement of the hemagglutinin (the viral attachment protein that also mediates the entry of the virus into the cell) with a novel subtype that has n [..]

A process by which a new influenza A virus hemagglutinin subtype (with or without an accompanying new neuraminidase subtype) is introduced into the human population, which lacks prior experience of an [..]

The process by which different influenza A viruses combine to result in a new subtype of virus. Antigenic shift may result in global disease spread, or pandemic, because humans will have few or no ant [..]

Mutation, i.e., sudden change in molecular structure of RNA/DNA in microorganisms, especially viruses, which produces new strains of the microorganism; hosts previously exposed to other strains have little or no acquired immunity to the new strain; antigenic shift is believed to be the explanation for the occurrence of strains of microorganisms, su [..]