PHENOTYPIC AND GENOTYPIC CHANGES IN A NEW CLONE COMPLEX OF NEISSERIA-MENINGITIDIS CAUSING DISEASE IN THE NETHERLANDS, 1958-1990

To characterize the phenotypic and genotypic changes that occurred in a new clone lineage of Neisseria meningitidis (lineage III) in the Net herlands, the electrophoretic type (ET) was determined for 79 serogrou p B isolates of serotype 4 or subtype P1.4 (or both) obtained between 1958 and 1990 from patients with systemic meningococcal disease. Thirt y-five previously described isolates were also included. After its app earance in 1980, lineage III started homogeneously with regard to both genotype (ET-24) and phenotype (B:4:P1.4). After 1984, other clones a ppeared in the lineage, and the various clones acquired other serotype s (serotypes 14 and 15) and subtypes (P1.2, P1.7, and P1.12), indicati ng frequent exchange of genetic material between clones. These results indicate that basing a serogroup B vaccine on outer membrane componen ts from a single strain is not a valid strategy for the prevention of meningococcal disease.