No abstract

The major outer membrane protein of chlamydial elementary bodies was identified in dimer, trimer, and other multimeric forms. These natural multimers were stabilized by disulfide-mediated cross-linking. Such cross-linking of outer membrane proteins may play an important role in the formation and evolution of chlamydial cell wall structure.

Sera from individuals with culture-proven genital infection with Chlamydia trachomatis were analyzed for the presence of antibodies to chlamydial proteins by an immunoelectrophoretic transfer method. Protein antigens from representative strains of the 15 known serotypes were resolved by gel electrophoresis and transferred to a nitrocellulose solid support before being probed with serum. Sera from infected patients reacted with many different proteins. Most of these sera reacted with a 60,000- and a 62,000-molecular-weight protein which were present in each of the C. trachomatis serotypes and clinical isolates analyzed. In contrast, reactions with the major outer membrane protein were frequently observed but were usually weak. Sera from control groups of children, cloistered nuns, and college women, who were presumed not to have had prior chlamydial infections, did not usually have antibodies against the 60,000- or 62,000-molecular-weight protein, but did react with the major outer membrane protein and a 29,000-molecular-weight protein. These observations may have implications for the development of serodiagnostic tests as well as the identification of candidate antigens for vaccine development.

Transmission of Chlamydia trachomatis and Neisseria gonorrhoeae among infected men and their female sex partners was examined using a design enhancing the likelihood that spread was directed from men to women. Chlamydia culture-negative specimens were examined using DNA amplification tests. Infection rates in women exposed to male sex partners with Chlamydia only were 65% (20/31) and with gonorrhea only were 73% (33/45). Infection of women by either agent was not influenced by the number of sexual exposures to or coinfection in men. There was a 98% (40/41) concordance of N. gonorrhoeae isolates among partners by auxotype and serovar. Chlamydia isolates were serotyped using ELISA and immunofluorescence testing and confirmed by nested polymerase chain reaction: 50% (6/12) of men and 57% (8/14) of women yielded mixed serovars. Sixty-four percent of pairs (9/14) were infected with identical serovars and an additional 28% shared at least one serovar. Multiple serovars of C. trachomatis, but not of N. gonorrhoeae, were common in sex partners and exchanged frequently.

The synthesis and accumulation of Chlamydia trachomatis outer membrane proteins within infected HeLa 229 host cells were monitored by assessing the uptake of [35S]cysteine into chlamydial proteins during the 48-h growth cycle of a lymphogranuloma venereum strain, L2/434/Bu. Synthesis of the major outer membrane protein, a protein that accounts for about 60% of the outer membrane protein mass of elementary bodies (EB), was first detected between 12 and 18 h after infection. The uptake of [35SJcysteine into the 60,000-molecularweight doublet (60K doublet) and 12.5K cysteine-rich proteins was not observed until 30 h after infection, when the intracellularly dividing reticulate bodies were beginning to transform into infectious EBs. By using a more sensitive immunoblotting method in conjunction with monoclonal antibodies specific for the 60K doublet proteins, synthesis of these proteins was detected even earlier, by 18 h after infection. These data suggest that the time and extent of synthesis of these outer membrane proteins are regulated by processes that coincide in time with the transformation of reticulate bodies into EBs. Additional studies were performed to determine the extent of disulfide cross-linking of outer membrane proteins during the growth cycle. Both the major outer membrane protein and the 12.5K protein became progressively cross-linked to about 60% during the last 24 h of the growth cycle, whereas the 60K doublet proteins were extensively cross-linked during most of the cycle. These data may indicate an intracellular cross-linking mechanism, possibly enzymatic, that exists in addition to an auto-oxidation mechanism that occurs upon host cell lysis and exposure to the extracellular environment.

To better understand the prevalence, incidence, and risk factors for sexually transmitted diseases (STDs) among female adolescents, a prospective 6-month cohort study was conducted at four teen clinics in a southeastern city. At enrollment, 260 (40%) of 650 sexually active females ages 14-19 years had an STD: chlamydia, 27%; herpes simplex virus type 2 (HSV-2), 14%; gonorrhea, 6%; trichomoniasis, 3%; and hepatitis B, 2%. At follow-up, 112 (23%) of 501 participants had an incident infection: chlamydia, 18%; HSV-2, 4%; gonorrhea, 4%; and trichomoniasis, 3%. At either enrollment or follow-up, 53% had >/=1 STD; of those with 1 lifetime partner, 30% had an STD. Having a new partner (odds ratio [OR], 2.2; 95% confidence interval [CI], 1. 1-4.2) or friends who sell cocaine (OR, 1.6; CI, 1.0-2.6) was independently associated with incident infection. STD incidence and prevalence were extremely high in this population, even in teenagers with only 1 lifetime partner. Individual risk behaviors appeared less important for STD risk than population factors.

The frequent presence of chlamydia among patients at STD clinics who received treatment for gonorrhea, including sex partners of gonorrhea-infected patients, supports continuing current recommendations for co-treatment.

The objective of this study was to characterize the humoral immune response to chlamydial genital infection of mice with the mouse pneumonitis agent (MoPn). With an enzyme-linked immunoabsorbent assay, immunoglobulin G antibodies to MoPn were first detected in plasma by day 14. Peak plasma antibody concentrations were reached by day 49, and this reponse did not decline significantly throughout the 300-day monitoring period. Immunoglobulin A against MoPn could first be detected in pooled vaginal washes by day 21 after infection and had reached peak concentrations by day 28, but anti-MoPn immunoglobulin G was not consistently present in secretions. The antibody response in secretions had declined slightly by day 300. Immunoblot analysis revealed that the early phase of the plasma antibody response to MoPn as a result of genital infection was against lipopolysaccharide, the major outer membrane protein, and a 62-kilodalton (kDa) protein. In secretions, early-phase immunoglobulin A antibodies were directed to the major outer membrane protein and lipopolysaccharide. Late reactions to 15-, 22-, and 83-kDa proteins in plasma were noted. Late reactions to the 62-kDa protein in secretions were also noted. The cause of these late responses remains unexplained. When mice were challenged intravaginally with MoPn at 50-day intervals after the primary infection, it was found that mice inoculated on day 100 or after were susceptible to reinfection. Susceptibility could not be related to a decline in the antibody concentration in plasma or secretions or in the antibody response to specific components of MoPn as measured by immunoblot analysis.