FREQUENCY OF PILIN ANTIGENIC VARIATION IN NEISSERIA-GONORRHOEAE

Variation of the pilus of Neisseria gonorrhoeae occurs by the recombin ation of silent pilin DNA sequences into the pilin expression locus. W e have developed a quantitative, competitive reverse transcription-PCR assay which measures the frequency of pilin antigenic variation indep endently of changes in gonococcal colony morphology and have determine d this frequency within a gonococcal population. We have also studied the frequency of antigenic variation during growth and have concluded that growth does not dramatically influence the frequency of pilin ant igenic variation, although a reproducible, twofold increase is observe d upon the transition into late log/stationary phase.