Anti-C. trachomatis MOMP (full length) polyclonal antibody [FITC]

Chlamydia trachomatis is an obligate intracellular bacterium. C. trachomatis infection is the most prevalent bacterial sexually transmitted infection and can lead to pelvic inflammatory disease and infertility in women. There is no licensed vaccine for C. trachomatis prevention, in part due to gaps in our knowledge of C. trachomatis-specific immune responses elicited during human infections. Previous investigations of the antibody response to C. trachomatis have identified immunodominant antigens and antibodies that can neutralize infection in cell culture. However, epitope-specific responses to C. trachomatis are not well characterized, and the impact of these antibodies on infection outcome is unknown. We recently developed a technology called deep sequence-coupled biopanning that uses bacteriophage virus-like particles to display peptides from antigens and affinity select against human serum IgG. Here, we used this technology to map C. trachomatis-specific antibodies in groups of women with defined outcomes following C trachomatis infection: (i) C. trachomatis negative upon presentation for treatment ("spontaneous resolvers"), (ii) C. trachomatis negative at a 3-month follow-up visit after treatment ("nonreinfected"), and (iii) C. trachomatis positive at a 3-month follow-up after treatment ("reinfected"). This analysis yielded immunodominant epitopes that had been previously described but also identified new epitopes targeted by human antibody responses to C. trachomatis. We focused on human antibody responses to the C. trachomatis variable domain 4 serovar-conserved region of the major outer membrane protein (VD4-MOMP), a previously described immunodominant epitope. All three groups of women produced IgG to the VD4-MOMP, suggesting that detection of serum antibodies to VD4-MOMP in women with urogenital C. trachomatis infection is not associated with protection against reinfection. IMPORTANCE C. trachomatis infection is the most common bacterial sexually transmitted infection, and infection in women can lead to pelvic inflammatory disease and infertility. No licensed vaccine exists to prevent C. trachomatis infection, and investigations of the natural immune response may inform the design of targeted vaccines for C. trachomatis. Our study fills a gap in knowledge regarding the epitope specificity of antibody responses that are elicited in response to C. trachomatis infection in women. We identified several new B cell epitopes for C. trachomatis antigens and confirmed B cell epitopes that have been identified by other methods. Our finding that women produce antibodies to the VD4-MOMP regardless of infection outcome provides insight into vaccine development, suggesting that vaccines targeting VD4-MOMP may need to elicit higher-titer antibody responses than natural infection imparts or that additional vaccine targets should be pursued in the future.

The administration of an efficacious vaccine is the most effective long-term measure to control the genital tract infection caused by Chlamydia trachomatis (Ct) in humans. The current challenge for Ct vaccine development is to develop an effective delivery vehicle for induction of a high level of mucosal T and complementary B cell responses. We evaluated the immunogenicity and efficacy of a candidate vaccine comprising the major outer membrane protein (MOMP) multiepitope of Ct delivered with the human papillomavirus (HPV) major capsid protein L1 as a vehicle with adjuvant properties, in a murine model of chlamydial genital infection. A recombinant plasmid pcDNA3.1(+) containing mammalian codon-optimization HPV6b L1 gene and Ct MOMP multiepitope was constructed. The Ct MOMP multiepitope containing T- and B-cell epitope-rich peptides was inserted into C-terminal of HPV6b L1-coding sequence. The constructed plasmid after verified by enzyme restriction assay and DNA sequencing was transfected into COS-7 cells. Expression of the chimeric gene in COS-7 cells was confirmed by RT-PCR, Western blot analysis and immunofluorescence assay. Results revealed successful expression of the chimeric HPV6b L1/Ct MOMP multiepitope gene both at the mRNA and protein levels in transfected COS-7 cells. Intramuscular (IM) administration in mice was able to elicit not only antibodies against Ct MOMP, but also Th1 and cytotoxic T lymphocyte activity against the Ct MOMP epitopes. In addition, recipients of IM immunization of HPV6b L1/Ct MOMP multiepitope were highly resistant to infection. Altogether, the results suggested that IM delivery of HPV6b L1-MOMP multiepitope may be a suitable vaccine regimen potentially capable of inducing protective mucosal immunity against Ct infection. (C) 2011 Elsevier Ltd. All rights reserved.