The influenza virus: Antigenic composition and immune response.

The architecture and chemical composition of the influenza virus particle is described with particular reference to the protein constituents and their genetic control. The dominant role in infection of the surface proteins - haemagglutinins and neuraminidases - acting as antigens and undergoing variation in time known as antigenic drift and shift is explained. The immuno-diffusion technique has illuminated the interrelationships of the haemagglutinins of influenza A viruses recovered over long periods of time. The H0 and H1 haemagglutinins are now regarded as a single sub-type with H2 and H3 representing the haemagglutinins of the 1957 and 1968 sub-types. Animal influenza viruses of pigs, horses and birds are described. A relation to human influenza strains has been shown to exist in certain instances as is the capacity of some human strains to pass to the animal kingdom.