Phenotypic and genotypic changes in a new clone complex of Neisseria meningitidis causing disease in The

To characterize the phenotypic and genotypic changes that occurred in a new clone lineage of Neisseria meningitidis (lineage III) in the Netherlands, the electrophoretic type (ET) was deter-mined for 79 serogroup B isolates of serotype 4 or subtypePIA (or both) obtained between 1958 and 1990 from patients with systemic meningococcal disease. Thirty-five previously described isolates were also included. After its appearance in 1980, lineage III started homogeneouslywith regard to both genotype (ET-24) and phenotype (B:4:P1.4). After 1984, other clones appeared in the lineage, and the various clones acquired other serotypes (serotypes 14 and 15) and subtypes (P1.2, P1.7, and Pl.I2), indicating frequent exchange of genetic material betweenclones. These results indicate that basing a serogroup B vaccineon outer membrane components from a single strain is not a valid strategy for the prevention of meningococcal disease. Meningococci are classified into serogroups, serotypes, and subtypes on the basis of antigenic differences in their capsular polysaccharides, class 2/3 outer membrane proteins (OMPs), and class I OMPs, respectively [I]. Studying the distribution of these surface structures has proved useful fo