Abstract
Sonicates of eight Neisseria species from man were analysed in a micro-Ouchterlony double-diffusion absorption assay in comparison with a gonococcal reference antiserum-antigen system. Five major gonococcal precipitin zones were identified which comprised genus-, species- and type-specific components. One antigen was found in all strains of three species with pathogenic capability--N. gonorrhoeae, N. meningitidis and N. flavescens. It was not detected in N. lactamica, N. pharyngis, N. elongata, N. cinerea or N. catarrhalis.