POLYMERASE CHAIN-REACTION AND DIRECT SEQUENCING OF NEISSERIA-GONORRHOEAE PROTEIN-IB GENE - PARTIAL NUCLEOTIDE AND AMINO-ACID-SEQUENCE ANALYSIS OF STRAIN-S4, STRAIN-S11, STRAIN-S48 (SEROVAR-IB4) AND STRAIN-S-34(SEROVAR-IB5)

A pair of primers were designed for the polymerase chain reaction (PCR ) to amplify a 341-base pair fragment of the gene encoding the outer m embrane protein IB (PIB) of Neisseria gonorrhoeae. This PCR technique is specific and sensitive, being able to detect gonococcal strains bel onging to ten different PIB serovars, but not PIA gonococcus nor other negative control bacteria. PCR products of four representative PIB st rains were directly sequenced. Of the three strains belonging to serov ar IB4, two (S11 and S48) shared identical nucleotide and amino acid s equences in the PIB region examined. The third IB4 strain (S4) reveale d sequences identical to the published IB26 strain (P9). The sequences of strains P9, S4, S11 and S48 were found to differ from those of str ain S34 (serovar IB5). The PCR sequencing technique can further differ entiate strains belonging to a common serovar and establish clonal rel ationships among strains. As a molecular epidemiological tool, the PCR -sequencing strategy can augment existing typing methods including ser otyping.