Chlamydia trachomatis major outer membrane protein variants escape neutralization by both monoclonal antibodies and human immune sera.

We have identified two families of novel Chlamydia trachomatis isolates with amino acid changes within the major outer membrane protein (MOMP) variable domains: one family of Da, D*, and D- and one family of Ia and I-. In order to determine whether these MOMP variants can escape antibody neutralization of infectivity, we tested both the D and I prototype strains and the variants in a complement-independent in vitro neutralization assay. We found that variants can indeed escape neutralization by both monoclonal antibodies and polyclonal human immune sera that neutralize the prototype strain.

Sequence conservation in the major outer membrane protein gene among Chlamydia trachomatis strains isolated from the upper and lower urogenital tract.

To determine the extent of nucleotide sequence variation in the major outer membrane protein (MOMP) gene among 27 clinical isolates of Chlamydia trachomatis, the MOMP gene was amplified from 13 strains isolated from the endometrium of patients with pelvic inflammatory disease and high titers of anti-chlamydial antibodies and from 14 strains isolated from the cervix of patients with presumed first-time chlamydial infection. Amplified MOMP variable domain DNA from these isolates was directly sequenced and compared with previously published results. Very little sequence heterogeneity in the MOMP variable domains was found in all 27 clinical isolates, suggesting that MOMP sequence heterogeneity is not often associated with the spread of C. trachomatis to the upper genital tract and is not common in the chlamydial strains in the patient population studied.

Long-term eradication of Chlamydia trachomatis genital infection after antimicrobial therapy. Evidence against persistent infection.

OBJECTIVE: To determine whether Chlamydia trachomatis urogenital infections persist or relapse after antimicrobial therapy by serial measurement of chlamydial-specific DNA using the polymerase chain reaction (PCR), cell cultures, and serological studies. DESIGN: Prospective evaluation of an inception cohort. SETTING: University student health clinic. PARTICIPANTS: Twenty women with culture-proven and PCR-proven C trachomatis urogenital infections. MEASUREMENTS: Incidence of persistent infection as determined by PCR, culture, and serial measurement of local and systemic antibody to C trachomatis for 5 months after doxycycline therapy. RESULTS: Prior to therapy, C trachomatis was isolated in cell culture from the cervix in 19 of 20 women, from the urethra in 13 women, and from the rectum in 13 women. All culture-positive specimens were also PCR-positive. Immediately after completion of antimicrobial therapy, all women had negative cell cultures for chlamydia. Ten of 20 culture-negative cervical specimens and two culture-negative urethral specimens had chlamydial DNA present immediately after treatment. In addition, three women had detectable DNA from cervical specimens 1 week after treatment. The presence of cervicitis (P = .01), high inclusion counts (P = .004), and serological evidence of recent infection (P = .0004) were each significantly associated with PCR positivity after treatment. All 384 subsequent cervical, rectal, and urethral specimens collected over 5 months were negative by both PCR and culture with the exception of one woman who was reinfected. Serum immunoglobulin M (IgM) titers, geometric mean serum immunoglobulin G (IgG) titers, and prevalence of local antibody to chlamydia progressively declined after treatment. CONCLUSIONS: Standard antimicrobial therapy is effective in the long-term microbiologic eradication of uncomplicated C trachomatis urogenital infections. The presence of chlamydial DNA after antimicrobial therapy is of short duration and reflects excretion of nonviable organisms rather than persistent infection.