Preparation and immunogenicity of a purified influenza virus haemagglutinin and neuraminidase subunit vaccine.

A vaccine was prepared containing the haemagglutinin and neuraminidase subunits from the A/Port Chalmers. 1/73 (HN) strain of influenza virus. The virus particles were disrupted with ammonium deoxycholate and the matrix protein, which was insoluble in this detergent, was removed by centrifugation. Following removal of deoxycholate, the haemagglutinin and neuraminidase subunits aggregated by their hydrophobic ends, forming mixed clusters. These were then freed from nucleocapsids by electrophoresis. The haemagglutinin and neuraminidase subunits were as effective as intact inactivated virus (at equivalent concentration) in eliciting a late primary antibody response when injected in saline into rabbits. In humans also, the subunits were as immunogenic as intact inactivated virus particles at equivalent concentration. Many people, however, responded only to the ‘common’ antigenic determinant(s) on the haemagglutinin subunit of Port Chalmers/73 virus and did not respond at all to the ‘specific’ determinant(s). Sera from these people contained antibodies which reacted equally as well with Hong Kong/68 virus as with the Port Chalmers/73 strain and none which reacted exclusively with the latter virus.