| Abstract: | The chemical nature of the antigens of the meningococcal serotypes described by Frasch and colleagues was determined by a combination of immunodiffusion and the SDS-polyacrylamide gel electrophoresis immunoperoxidase technique (SGIP). It was confirmed that the serotype antigens of the outer membrane of serotypes 1, 2, 6, 9, 11 and 12 were proteins, whilst those of serotypes 4,5 and 8 were lipopolysaccharides. Serotype 2 can now be divided into three related types, provisionally called 2a (originally serotype 2), 2b and 2c with the specific antigens being proteins having molecular weights of 41,000, 41,500 and 41,500, respectively. A total of 195 strains of meningococci isolated from patients and carriers in the Netherlands and 20 serogroup Y strains from patients in the U.S.A. were serotyped by means of immunodiffusion. Serotype 2a could be demonstrated in some strains belonging to the serogroups B (only those from carriers), C, W-135 and Y (only those from the U.S.A.). The W-135 strains isolated from patients in this series more often belonged to serotype 2a than did the W-135 strains from carriers. Serotype 2b was present in about half of the serogroup B and a few serogroup C strains isolated from patients with meningitis, but absent in serogroup B and C strains from carriers. Serotype 2c could only be demonstrated in serogroup Y strains, both from the Netherlands and the U.S.A. The other serotypes were found only sporadically. |
