Differences in attachment antigens of gonococci in reinfection.

On the basis of bacterial typing, pyocin typing, and antibiotic sensitivity tests, two consorts appeared to have been reinfected 34 and 41 days later, respectively, with the same gonococcal strain, suggesting a failure in these patients to develop effective immunity to reinfection. However, these tests do not measure antigens which mediate attachment, a function which may correlate with virulence. When the above infecting strains were retested in an inhibition-of-attachment assay using rabbit gonococcal antisera, the antigens mediating attachment were found to be different. Homologous antisera inhibited attachment of the homologous strain at a high titer. Absorbing the antisera with the initial infecting strain did not remove any of the blocking activity of the antisera raised to the reinfecting strai, but the latter strain did share some attachment antigens in common with the initial infecting strain. Homologous antisera also bound preferentially to pili purified from the homologous strains.