LIPO-OLIGOSACCHARIDE IMMUNOTYPING OF NEISSERIA-MENINGITIDIS BY A WHOLE-CELL ELISA WITH MONOCLONAL-ANTIBODIES

To assess the applicability of a whole-cell ELISA (WCE) with monoclona l antibodies (MAbs) for lipo-oligosaccharide (LOS) immunotyping of Nei sseria meningitidis, 675 meningococcal isolates obtained in 1989 and 1 990 in the Netherlands and 57 isolates collected in 1974, of which the immunotype had been determined previously by microprecipitation, were analysed. Despite the lack of specific MAbs for L2 and L4, an algorit hm was developed for the assignment of immunotypes on the basis of the reaction patterns of the reference strains and these isolates to a co mbination of 14 MAbs. The immunotypes found by WCE were in accordance with those obtained by microprecipitation and the results from WCE wer e reproducible. The distribution of immunotypes among isolates of the various serogroups in the Netherlands in 1989-1990 is presented. Based on the reaction patterns of the isolates, two main categories of rela ted immunotypes could be distinguished among isolates of serogroups B and C: L2/L4 and L3/L1/L8. Some isolates of the latter category were o f one immunotype, but many isolates expressed one or two additional im munotypes, either strongly or weakly, indicating that the differences in this category are quantitative rather than qualitative. The results of this study have demonstrated that the WCE method for LOS immunotyp ing is easily applicable and provides better definition of test strain s for invitro bactericidal assays and research into pathogenesis.