A mechanism for variation by viruses that involves the accumulation of mutations within the antibody-binding sites so that the resulting viruses cannot be inhibited well by antibodies against previous strains making it easier for them to spread throughout a partially immune population. Antigenic drift occurs in both influenza A and influenza B viru [..]

A process by which circulating influenza viruses are constantly changing, which allows the viruses to cause annual epidemics of illness. Antigenic drift occurs when mutations accumulate in the hemaggl [..]

Change in the genetic makeup of a virus, especially an influenza virus, that leads to a new strain of the virus. Antigenic drift causes the virus’s outer surface to appear different to a host previous [..]

<immunology> A change that occurs on the molecular level to effect a change in the antigenicity of a bacteria or virus. Antigenic drift occurs naturally and more rapidly in certain viruses (for example HIV). It is antigenic drift which complicates the development of an effective HIV (AIDS) vaccine. (27 Sep 1997)