Partial protection against genital reinfection by immunization of guinea-pigs with isolated outer-membrane proteins of the chlamydial agent of guinea-pig inclusion conjunctivitis

Abstract

~ ~Because partial protection against reinfection is induced by experimental infection in the guinea-pig model of genital chlamydial infection, we sought to induce immunity by immunization. Female guinea-pigs were immunized subcutaneously with the major outer-membrane protein (MOMP) and the 61 kDa cysteine-rich outer-membrane protein (61 kDa) of the agent of guinea-pig inclusion conjunctivitis (GPIC) eluted from SDS-polyacrylamide gels (SDS-MOMP, SDS-61 kDa). Post-immunization sera and secretions contained antibodies to the SDS-purified proteins at high titre as measured by immunoblotting, whereas enzyme immunoassays (EIA) using whole elementary bodies as antigen showed significantly lower titres (P < 0.001). Likewise, blastogenic responses of peripheral mononuclear cells to GPIC elementary bodies were weak. Animals immunized with SDS-MOMP and SDS-61 kDa were fully susceptible to intravaginal challenge, as were control animals immunized with buffer without protein. Another group of animals were immunized with material prepared by extraction of chlamydial outer-membrane complexes with octyl /?-D-glucopyranoside (OGP) and dithiothreitol, which consisted largely of M O M P (OGP-MOMP). In contrast to the SDS-MOMP group, sera and secretions in the OGP-MOMP group showed high titres in EIA, and high titre antibodies to M O M P by immunoblot; however, most animals also had antibodies to 61 kDa, 72 kDa and ca. 84 kDa outer-membrane proteins. OGP-MOMP animals were partially protected against genital challenge as evidenced by low inclusion scores compared to control animals, although duration of infection measured by culture isolation was similar to controls. Immunoblot analysis of sera from immunized animals and from a group of immune animals post-infection was performed using recombinant fusion peptides containing the four variable domains of MOMP. No consistent differences in reaction patterns were observed when sera from protected and non-protected animals were compared. Thus, a highly refined outermembrane preparation is capable of producing partial immunity to genital infection. Further study is required to determine whether the protection is due to M O M P itself or to other outer-membrane proteins found in small amounts in the OGP-MOMP immunogen. The results suggest the possibility that discontinuous M O M P epitopes could play a role in inducing a protective immune response in the guinea-pig model, a concept that requires further evaluation.

Animal Models for Studying Female Genital Tract Infection with Chlamydia trachomatis

“…As already mentioned, the GPIC guinea pig model closely resembles disease following C. trachomatis infection in humans and is therefore suitable to evaluate potential vaccine candidates (104)(105)(106).…”

A Novel Recombinant Multisubunit Vaccine against Chlamydia

“…This 40-kDa immunodominant protein has been well characterized as a porin, an adhesin, a key determinant of chlamydial genus and species specificity, and a highly promising candidate vaccine. However, experience with purified or recombinant MOMP as a protective Ag in several animal models (7)(8)(9)(10)(11) suggests that MOMP alone is inadequate, calling either for a multisubunit approach or a more effective delivery system that will optimize the immune response.…”

Vaccination with theChlamydia trachomatisMajor Outer Membrane Protein Can Elicit an Immune Response as Protective as That Resulting from Inoculation with Live Bacteria

“…Immunization of mice with C. trachomatis MoPn subunit vaccines has also provided some encouraging results. For instance, immunization with the outer membrane has been shown to induce significant protection (3,34). A preparation of Mice were challenged in the ovarian bursa 4 weeks after the last i.m.-plus-s.c. boost (35).…”