Enzyme-linked immunosorbent assay for identification and measurement of antibodies to group A streptococcal bacteriophage.

A sensitive enzyme immunoassay (ELISA) was developed to identify and measure antibodies to group A streptococcal bacteriophage hyaluronidase. With a purified preparation of bacteriophage hyaluronidase as the solid-phase antigen, the ELISA was shown to be as specific as and more sensitive than the standard bacteriophage neutralization test for measurement of antibody to bacteriophage. In rabbits immunized with bacteriophage, the ELISA detected antibody earlier than the neutralization assay (7 vs. 11 days) and was able to distinguish IgG and IgM class antibodies. A strong correlation was demonstrated between antibody titers measured by ELISA and bacteriophage neutralization (r = 0.88; P less than 0.001). Preliminary data using the ELISA, modified to measure human antibody to bacteriophage hyaluronidase, indicated that an antibody response of both IgG and IgM classes occurred in humans after group A streptococcal infection. This ELISA provided a sensitive method for detection and measurement of antibody to a specific bacteriophage antigen, which will be useful in the investigation of the role of bacteriophage in the pathogenesis of group A streptococcal infections.