Switching, Antigenic

Medical Condition:
Switching, Antigenic

Change in the surface antigen of a microorganism. There are two different types. One is a phenomenon, especially associated with the influenza virus, where it undergoes spontaneous antigenic variation both as slow antigenic drift and sudden emergence of a new strain (antigenic shift). The second type is when certain parasites, especially trypanosomes, plasmodia, and Borrelia, survive the immune response of the host by changing the surface coat (antigen switching). (From Herbert et al., The Dictionary of Immunology, 4th ed)