A chlamydial major outer membrane protein extract as a trachoma vaccine candidate.

PURPOSE: As shown in infected humans and in animal models of chlamydial infection, the major outer membrane protein (MOMP) of Chlamydia trachomatis is immunogenically potent. The purpose of this investigation was to test in the cynomolgus monkey model of trachoma a new extract of MOMP as a candidate vaccine against ocular chlamydial infection. METHOD: The nonionic detergent octyl-beta-D glucopyranoside (OGP) was used to extract MOMP from purified C. trachomatis (serovar C) elementary bodies. Protective immunization with OGP-MOMP by mucosal and systemic routes was compared in the cynomolgus monkey model of trachoma. All control and immunized monkeys were challenged by topical application of infectious C. trachomatis to the conjunctivae 35 days after the initiation of immunization. RESULTS: Immunization with OGP-extracted MOMP successfully induced chlamydia-specific local and systemic immunity to MOMP and to whole organism before challenge and early clearance of infection by systemically immunized monkeys. Although ocular disease was not significantly reduced in either immunized group compared to control animals, the lowest clinical and microbiologic disease scores developed in two animals in the mucosal group with the highest immunoglobulin A tear antibody titers at day 0 to 14, whereas higher tear and serum immunoglobulin G correlated with reduced disease in the systemically immunized group. CONCLUSIONS: These data demonstrate that despite evidence of vigorous MOMP-specific and other chlamydia-specific serologic and cell-mediated immunity, as well as anamnestic serologic responses to chlamydia, vaccination with OGP-MOMP was only partially protective against chlamydial ocular disease. The partial protection correlated best with tear immunoglobulin A responses after mucosal immunization and with local and systemic immunoglobulin G responses after peripheral immunization, suggesting that alternative chlamydial antigens may have to be considered in future vaccine development to induce more effective protective immunity and that evaluation of efficacy must be appropriate to route of immunization.

Trachoma in a rural Haitian community.

We selected 43 patients, aged 15 days to 57 yesrs, for intensive study after screening 975 people for clinical evidence of trachoma in rural Haiti. Trachoma was present in Haiti with low endemicity and was followed by relatively mild sequelae. Laboratory studies confirmed the disease through demonstration of conjunctival inclusion bodies by immunofluoresence and serotyping of antibody in sera or eye secretions, or both. Of 23 patients (age 1 to 36 years) with active trachoma, all had serum antibody to chlamydia (range 1:10 to 1:640), nine had eye secretion antibody (range 1:10 to 1:1280), and one was inclusion positive. The remaining 20 patients (age 15 days to 57 years) had the following diagnosis: atypical follicles (eight), conjunctivitis with or without mucopurulent discharge (ten) innactive pannus only (one), and severe anemia (one). Only 16 of the 20 were tested for serum antibody and all were positive (1:10 to 1:5,120), 11 of 20 had eye secretion antibody (1:10 to less than or equal to 1:640), and one was inclusion positive. Serotyping attempted on 22 patients yielded 16 patients with antibodies specific for type A, one patient with type B, and five who were not typed.