Opacity Proteins of Neisseria Gonorrhoeae in Lipooligosaccharide Mutants Lost Ability to Interact with Neutrophil-restricted CEACAM3（CD66d）

Lipooligosacharide(LOS) of Neisseria gonorrhoeae(gonococci, GC) is involved in the interaction of GC with host cells. Deletion of the alpha-oligosaccharide(alpha-OS) moiety of LOS(lgt F mutant) significantly impairs invasion of GC into epithelial cell lines. GC opacity(Opa) proteins, such as Opa I, mediate phagocytosis and stimulate chemiluminescence responses in neutrophils in part through interaction with members of the carcinoembryonic antigen(CEA) family, which includes CEACAM3(CD66d), a human neutrophil specific receptor for phagocytosis of bacteria. In the present work, we examined the effects of Opa I-expressing lgt F mutant on phagocytosis by He La-CEACAM3 cells and chemiluminescence responses in neutrophils. The results showed that lgt F mutant even expressing Opa I completely lost the ability to promote either phagocytosis mediated by CEACAM3 interaction in He La cells or chemiluminescence responses in neutrophils. These data indicated that Opa proteins in the lgt F mutant, which might result from the conformational change, cannot be functional.