A serological study of somatic antigens from Haemophilus influenzae and two related species.

Somatic antigenic preparations from Haemophilus influenzae strains, types a-f, and from non-capsulated H. influenzae strains obtained from the oral cavity of healthy individuals were analysed with the double-diffusion technique by means of antisera against the capsulated strains. The somatic precipitinogenic pattern of each of these strains, consisting of 12--20 lines, was very similar. In addition, the somatic antigenic pattern of one H. parainfluenzae strain and one strain tentatively designated H. haemoglobinophilus were studied. Precipitinogens common to H. influenzae as wel as strain-specific precipitinogens were demonstrated in these strains. It is concluded that immunodiffusion analyses might be of value for taxonomic studies of the genus Haemophilus.