SIALYLATION LESSENS THE INFECTIVITY OF NEISSERIA-GONORRHOEAE MS11MKC

In a human challenge experiment, the infectivity of gonococci with sia lylated lipooligosaccharide (LOS) was compared with the infectivity of gonococci with unsialylated LOS. Volunteers were intraurethrally inoc ulated with similar to 5000 sialylated or unsialylated piliated, non-o paque (P(+)Opa(-), transparent) colony type gonococci, strain MS11mkC. Five (83%) of 6 volunteers inoculated with unsialylated gonococci bec ame infected; however, only 1 of 5 volunteers became infected with sia lylated gonococci. The unsialylated gonococcal infections, with a medi an incubation time of 62 h (range, 32-98), were similar to previously described experimental infections, Gonococci shed by infected voluntee rs showed a transition from the P(+)Opa(-) phenotype of the inoculatio n strain to the P(+)Opa(+) (piliated, opaque) phenotype 12-60 h before onset of disease. The subject with sialylated gonococcus infection ha d an extended incubation period, showing a progressive increase in the number of organisms shed until he became symptomatic on day 6 after i noculation. These results show that gonococci with sialylated LOS are less infective than gonococci with unsialylated LOS.