HUMAN VACCINATION WITH ESCHERICHIA-COLI J5 MUTANT INDUCES CROSS-REACTIVE BACTERICIDAL ANTIBODY AGAINST NEISSERIA-GONORRHOEAE LIPOOLIGOSACCHARIDE

The lipopolysaccharides of enteric gram-negative bacteria and the lipooligosaccharides (LOS) of Neisseria gonorrhoeae may share antigenic determinants that are targets of bactericidal antibody. Natural (disseminated) infection with a serum-resistant gonococcal strain and immunization with Escherichia coli J5 stimulated bactericidal IgG anti-LOS antibodies that recognize different serum-resistant gonococcal LOS epitopes. In bactericidal assays, convalescent serum from disseminated infection killed only the homologous strain while post-J5 vaccination serum killed 6 of 9 additional strains. Both convalescent and post-J5 vaccination sera mediated marker (Cr-51) release from liposomes sensitized with serum-resistant gonococcal LOS (homologous strain), linking acquired killing activity to cross-reacting anti-LOS antibody. Post-J5 IgG mediated Cr-51 release more effectively than did convalescent IgG. Thus, bactericidal antibody elicited by J5 vaccination is more efficacious and broadly cross-reactive against serum-resistant gonococci than is antibody elicited by natural infection. Moreover, multiple LOS epitopes may serve as bactericidal targets on serum-resistant gonococci.