The 70-Kd neisserial common antigen is a surface-exposed, antigenically stable peptidic structure.

A previously described 70-Kd antigen present in all Neisseria gonorrhoeae strains tested and in most Neisseria species was characterized as a mercaptoethanol-and heat-stable protein. Using mouse polyclonal antisera specifically directed against this antigen, it was shown that it is a surface-exposed structure. The 70-Kd antigen was recovered from all gonococcal strains isolated from different anatomic sites in male and female partners, thus demonstrating its antigenic stability after in vivo transmission in humans.