STUDIES ON THE COMPLEMENT FIXATION ANTIGENS OF INFLUENZA VIRUSES TYPES A AND B.

Two types of specific particles can be obtained from allantoic fluid preparations of influenza A and B virus. The larger particle which possesses all the attributes of the virus and which shows a sedimentation constant of about 600 S was compared with the smaller component (30 S) by complement fixation technic. The 30 S component can be differentiated from the 600 S particle by the patterns of the optimal antigen-antibody relationships and by cross-absorption of the sera with the two particles. Some of the 30 S-type antigen can be demonstrated in higher concentrations of the 600 S particles by the use of sera containing only anti-30 S; i.e., sera carefully absorbed with 600 S component. Also, upon sonic vibration of the 600 S particle, serologically active material was released which behaved in every respect like the 30 S antigen. The response of human beings to these antigens was found to vary. Antibodies to the 30 S component developed in the majority of subjects exposed to active virus either under epidemic or experimental conditions, but only rarely following vaccination with three different vaccines. In selecting sera without 30 S antibodies a fairly close correlation between the antibody titers obtained by inhibition of hemagglutination and complement fixation with the 600 S component was obtained. The presence of 30 S antibodies prevented such a correlation. The reaction with the 30 S antigen may be of value in the diagnosis and study of the epidemiology of influenza.