MULTIPLE GONOCOCCAL OPACITY PROTEINS ARE EXPRESSED DURING EXPERIMENTAL URETHRAL INFECTION IN THE MALE

The opacity (Opa) proteins of Neisseria gonorrhoeae are a family of ou ter membrane proteins demonstrating phase and antigenic variation. N. gonorrhoeae strain FA0190 has 11 opa loci that encode at least 8 antig enically distinct Opa proteins. To determine if expression of one Opa protein or a subset of them is favored during gonococcal infection, we inoculated Opa-negative variants of strain FA1090 intraurethrally int o male volunteers. The Opa phenotype of gonococci isolated from urine and urethral swab cultures from nine infected subjects was determined. Opa proteins were expressed in a large proportion of the reisolates f rom the infected subjects. Gonococci cultured from urine or urethral s wab samples from six of the subjects were uniformly Opa positive, with the predominant Opa variants differing among subjects. Three differen t Opa proteins were represented as the predominant type in at least on e subject each. In three subjects, there was more heterogeneity in Opa phenotype of the reisolates, including the presence of Opa-negative v ariants. An increase in the proportion of isolates expressing multiple Opa proteins occurred over time in most subjects. Passage of the inoc ulum in vitro did not result in similar changes in Opa expression. The re was no detectable difference in infectivity of an Opa-negative vari ant and one expressing an Opa protein (OpaF) that was highly represent ed in reisolates from the original nine subjects. Reisolates from thre e infected volunteers inoculated with the OpaF variant showed continue d expression of OpaF alone or in conjunction with other Opa proteins. These results demonstrate that there is strong selection for expressio n of one or more Opa proteins by strain FA1090 in vivo, but that no si ngle protein is preferentially expressed during early infection in the male urethra.