IMMUNOGENICITY OF NEISSERIA-GONORRHOEAE LIPOOLIGOSACCHARIDE EPITOPE 2C7, WIDELY EXPRESSED IN-VIVO WITH NO IMMUNOCHEMICAL SIMILARITY TO HUMAN GLYCOSPHINGOLIPIDS

Natural infection with Neisseria gonorrhoeae may elicit a substantial antibody response directed against gonococcal lipooligosaccharide. Mon oclonal antibody (MAb) 2C7 recognized a gonococcal lipooligosaccharide epitope, identified the epitope directly in 94% of 68 consecutive cul ture-positive genital secretions, and recognized 95% of 101 randomly c hosen fresh (second-passage) gonococcal isolates, The epitope was stab ly maintained after multiple in vitro passages and did not compete wit h any of the known cross-reactive human glycosphingolipid structures, MAb 2C7 mediated in vitro killing and phagocytosis by human polymorpho nuclear leukocytes of 1 serum-sensitive (sialylated or not) and 1 stab ly serum-resistant gonococcal isolate that expressed the epitope. Gono coccal endometritis and disseminated infection elicited increases (6.5 -fold IgM, 4.4-fold IgG; 18-fold IgM, 17-fold IgG, respectively) in an ti-2C7 epitope antibody. Immunization with a gonococcal outer membrane vaccine elicited a mean 44.5-fold increase in IgG anti-2C7 epitope an tibody in 20 of 28 subjects. The epitope identified by MAb 2C7 may rep resent an excellent target for a potentially protective gonococcal vac cine candidate.