The lipopolysaccharide (R type) as a common antigen of Neisseria gonorrhoeae. I. Immunizing properties

Abstract

The ability of R-type lipopolysaccharide (LPS), isolated from Neisseria gonorrhoeae colony type 4, to protect against infection with N. gonorrhoeae colony type 1 (T1 isolates) in the mouse and chicken embryo was investigated. C57 black mice were immunized intraperitoneally with 50 μg of LPS, and challenged intracerebrally with 10–20 LD₅₀'s of N. gonorrhoeae colony type 1. Immunized mice were significantly protected (P < 0.01 to < 0.05) against challenge with different T1 isolates of N. gonorrhoeae when compared with non-immunized mice. Mice, injected with succinylated or alkali-treated LPS were not protected against gonococcal challenges.In a second animal model, leghorn hens were immunized intravenously with three injections of 500 μg of LPS followed by a booster of 2.5 mg 2 weeks later. Embryonated eggs obtained from immunized hens were protected against challenge with 5 × 10³ – 1 × 10⁴ LD₅₀'s of three different T1 isolates. When hens were injected with the chemically modified LPS, the embryos were not resistant to gonococcal challenge. The results of this study demonstrate the ability of R-type gonococcal LPS to provide protection against different T1 isolates of N. gonorrhoeae.