Serological grouping of virulent and avirulent strains of the lobster pathogen Aerococcus viridans.

Virulent strains of Aerococcus viridans (formerly Gaffkya homari) are the aetiologic agents of gaffkemia, a septicaemic disease of the American lobster (Homarus americanus). The virulent and avirulent forms of this bacterium, previously thought to be taxonomically indistinguishable, have been differentiated by serological studies. Antisera were produced in rabbits using autoclaved bacteria as antigens. Reactions were measured by agglutination tests using microtitre techniques and an antigenic scheme was determined. Specific antisera were prepared by absorption and used to determine antigens of strains of A. viridans and other Gram-positive cocci. In general, only virulent strains of A. viridans have antigen b. Both virulent and avirulent strains possess other antigens also detected in strains of the genus Staphylococcus.