Lipopolysaccharide serotyping of Neisseria meningitidis by hemagglutination inhibition

Abstract

Hemagglutination inhibition was used to investigate the antigenic diversity of lipopolysaccharide (LPS) from N. meningitidis and to develop a serotyping system based on this antigen. The system uses outer membrane complex prepared by a simple extraction procedure to inhibit homologous hemagglutination reactions involving sheep erythrocytes sensitized with purified LPS and rabbit antiserum raised to whole meningococci. Antisera with specificity for 8 different LPS determinants were used as typing sera to serotype a cross section of 67 meningococcal strains. Only 2 strains (both group A) were not typable with the 8 sera, and most strains had more than 1 type. Comparison of LPS type and bactericidal serotype suggests that the LPS and protein serotypes are independent serological markers.