IBV Hemagglutinin (B/Brisbane/60/2008) [His]

The influenza viruses are divided into 3 distinct immunological types (A, B, and C ) based upon their nucleocapsid and M protein antigens. Influenza A viruses also occur in pigs, birds, and horses. However, only man is infected by influenza B and C. Influenza type A viruses are divided into subtypes based on two proteins on the surface of the virus. These proteins are called hemagglutinin (HA) and neuraminidase (NA). There are 15 different hemagglutinin subtypes and 9 different neuraminidase subtypes so many different combinations are possible. The antigenic differences of the haemagglutinin and the neuraminidase antigens of influenza A viruses provide the basis of their classification into subtypes. eg. A/Hong Kong/1/68 (H3N2) signifies an influenza A virus isolated from a patient in Hong Kong in 1968, and of subtype H3N2. Influenza B virus is not divided into subtypes based on HA and NA.