Use of Staphylococcus aureus for rapid radioimmunoassay of influenza A virus haemagglutinin.

In a rapid method for the radioimmunoassay (RIA) of influenza A virus haemagglutinin, Staphylococcus aureus (strain Cowan I, Czechoslovak State Collection No Mau 55/64) was used for separation of bound and free antigens. With rabbit and human immune sera, the binding of antigen-antibody complexes to heat-killed, formalin-fixed staphylocci was comparable to the double antibody technique. The time required for the completion of binding reaction was about 10 min compared to 18--24 hr required for double antibody precipitation. S. aureus did not bind directly (i.e. in the absence of specific antibody) a significant amount of radiolabelled antigen.