ANTIGENIC RELATIONSHIP OF BRITISH SWINE INFLUENZA STRAINS TO STANDARD HUMAN AND SWINE INFLUENZA VIRUSES : THE USE OF CHICKEN AND FERRET ANTISERA IN RED CELL AGGLUTINATION.

The antigenic relationships of Type A (PR 8, WS) and Type B (Lee) human strains and the Shope and British (Cambridge, North Ireland) swine strains were studied by specific antiserum inhibition of chicken red cell agglutination by the influenza virus. The Cambridge and North Ireland strains were found to be closely related to the Type A strains and differentiated from the Shope virus. The distinctive antigenicity of the Lee strain of Type B was confirmed. Specific antibodies were developed in chickens following single intraperitoneal injections of influenza virus. Inhibition tests yielded results, in the antigenic analysis of the influenza viruses examined, comparable to those obtained with ferret antisera. Specific inhibition of hemagglutination by influenza virus proved an effective method for the study of strain relationships.