Definition of Antigenic shift

Antigenic shift: 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 not been present in human influenzaviruses for a long time. The source of these new genes is the large reservoir of influenzaviruses in waterfowl. The consequences of the introduction of a new hemagglutinin into human viruses is usually a pandemic, or a worldwide epidemic.


Last Editorial Review: 6/14/2012

Search MedTerms:


Back to MedTerms online medical dictionary A-Z List
Pill Identifier Tool

Need help identifying pills and medications?
Use the pill finder tool on RxList.


STAY INFORMED

Get the Latest health and medical information delivered direct to your inbox!