DIFFERENTIATION OF NEISSERIA-GONORRHOEAE IB-3 AND IB-7 SEROVARS BY DIRECT SEQUENCING OF PROTEIN IB GENE AND PULSED-FIELD GEL-ELECTROPHORESIS

Serotyping of Neisseria gonorrhoeae based on the differential recognit ion by a panel of six monoclonal antibodies (MAbs) against Protein IB (PIB) is a valuable tool for studying the epidemiology of gonorrhoea. However, the predominance of certain serovars in specific geographic r egions necessitates the development of new MAbs or new genotyping appr oaches. Nucleotide and amino-acid sequence analysis of PIB from strain s within the IB-3 and IB-7 serovars revealed strain differences within the same serovar. Based on the generation of PIB nucleotide and deduc ed amino-acid sequences that centred on amino-acid residues 196 and 23 7, eight serovar IB-3 strains and nine serovar IB-7 strains were separ ately subdivided into five groups. Intra-serovar differences were also established by pulsed-field gel electrophoresis (PFGE) of macro-restr iction fragments generated by SpeI- and NheI-cleavage of genomic DNA. There was good correlation between the results based on PIB gene PCR-s equencing and those based on PFGE analysis of macro-restriction fragme nt patterns. These data demonstrate the high precision of PFGE analysi s and indicate that this approach can be used as a rapid epidemiologic al subtyping system for major serovars of N. gonorrhoeae.