Trachomatis Major Outer Membrane Protein Research Articles

Improving potency of Chlamydia trachomatis major outer membrane protein muli-epitope DNA vaccine by fusion with human papillomavirues 6b L1

Effective adjuvants are needed to design effective vaccines against Chlamydia trachomatis (Ct). The aim of this study was to observe the immune response stimulated by inoculation of a DNA vaccine encoding a fusion protein comprising multiple Ct major outer membrane protein (MOMP) epitopes and human papillomavirus 6b L1 (HPV 6b L1) as the basis for designing a novel DNA vaccine against genital Chlamydia infections. The recombinant sequence encoding MOMP multi-epitopes was tandemly inserted and engaged downstream of HPV 6b L1 to construct a plasmid vaccine. COS-7 cells were transfected with pcDNA3.1(+)/Ct MOMP 168 encoding the Ct MOMP multi-epitope gene and co-expressed with the nucleic vaccine plasmid pcDNA3.1(+)/HPV 6b L1/Ct MOMP 168, which contains both the HPV 6b L1 and Ct MOMP multi-epitope genes. In addition, BALB/ c mice were inoculated intramuscularly (i.m.) with pcDNA3.1(+)/HPV 6b L1/Ct MOMP 168 or pcDNA3.1(+)/Ct MOMP 168. Serum IgG and secretory IgA (sIgA) in vaginal washes were then measured. The expression of HPV 6b L1/Ct MOMP multi-epitope was confirmed by western blotting, confocal microscopy and RT-PCR. Mice vaccinated with pcDNA3.1(+)/HPV 6b L1/Ct MOMP 168 had significantly higher IgG and sIgA antibody titers than pcDNA3.1(+)/Ct MOMP 16 controls. The results show that genetic fusion of the molecular adjuvant HPV 6b L1 to Ct MOMP 168 significantly increases the antigen-specific antibody response induced by the Ct MOMP 168 DNA vaccine.

The cellular immune response produced in BALB/c mice immunized with HPV6b L1/Ct MOMP multi-epitope chimeric DNA

Objective To study on the specific cellular immune response produced in BALB/c mice immunized with human papillomavirus (HPV) type 6b capsid protein L1 and Chlamydia trachomatis (Ct) major outer membrane protein(MOMP) multi-epitope chimeric DNA (HPV6b L1/Ct MOMP multiepitope) , and the enhancement of the specific cellular immune response to Ct MOMP multi-epitope by HPV6b L1. Methods The Ct MOMP multi-epitope gene was connected to the C terminal of HPV6b L1,the gene of HPV6b L1 had been optimized according to the codon usage of eukaryotic system, and then the HPV6b L1/Ct MOMP multi-epitope chimeric gene was cloned to pcDNA3.1 ( + ) vector. After identification by restriction enzyme digestion and DNA sequencing, the recombinant plasmid was transfected into COS-7 cells, Indirect Immunofluorescence (IIF) was used to confirm the expression of proteins. Then, BALB/c mice were randomly assigned to receive (intramuscular injection) either pcDNA3.1 ( + )/HPV6b L1/Ct MOMP or pcDNA3.1 ( + )/Ct MOMP or pcDNA3.1 ( + ) or PBS ( n = 12, 150 μg/time), and the same immunization schedule was repeated third times at 2 week intervals. The level of cytokine( IFN-γ, IL-4, IL-10) -producing CD3+ T cells in spleen, the cytotoxicity of Ct MOMP-specific and HPV6b L1-specific cytotoxic T lymphocyte (CTL) in spleen were detected by intracellular cytokine staining-fluorescence activated cell sorter (ICS-FACS) and LDH release assays, respectively. Results After immunization, when the efCTL (44.56%±4.02%, 35.35% ±2.89% ) and HPV6b L1 specific cytotoxicity of CTL (27.08% ±2.04%, 21.68% ±4.06% ) in pcDNA3.1 ( + )/HPV6b L1/Ct MOMP multi-epitope chimeric DNA immunized mice, were significantly higher than that in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA (35.50%±2.68%, 30.24% ±1.75%; 12.27% ±3.36%, 9.32% ±3.07%) and other control groups(F=72.87, F=114.55, P＜0.05; F=30.04, F=10.47, P＜0.05), and Ct MOMP multi-epitope specific cytotoxicity of CTL in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA immunized mice were significantly higher than that in control groups( F = 58.85, F = 120.21; P<0.05). The level of intracellular cytokine IFN-γ in pcDNA3.1 ( + )/HPV6b L1/Ct MOMP multi-epitope DNA immunized mice(4.34% ±0.06%)was higher significantly than that in pcDNA3.1 ( + )/Ct MOMP multi-epitope DNA immunized mice(3.14% ± 0.18%, P<0.05 ) and other control groups ( F = 473.83, P<0.05 ), while, the levels of IL-4 ( F =0.97, P ＞ 0.05 ) and IL-10 ( F = 2.25, P ＞ 0.05 ) had no significant difference between groups. Conclusion Both Ct MOMP and HPV6b L1 protein specific cellular immune response could be induced in BALB/c mice immunized with HPV6b L1/Ct MOMP multi-epitope chimeric plasmid, and the HPV6b L1 gene optimized by eukaryotic codon could significantly enhance the cellular immune response induced by Ct MOMP multi-epitope gene in BALB/c mice. Key words: Human papillomavirus; Chlamydia trachomatis; Major outer membrane protein; CTL; Epitope

Chlamydia trachomatis antigens in enteroendocrine cells and macrophages of the small bowel in patients with severe irritable bowel syndrome

BackgroundInflammation and immune activation have repeatedly been suggested as pathogentic factors in irritable bowel syndrome (IBS). The driving force for immune activation in IBS remains unknown. The aim of our study was to find out if the obligate intracellular pathogen Chlamydia could be involved in the pathogenesis of IBS.MethodsWe studied 65 patients (61 females) with IBS and 42 (29 females) healthy controls in which IBS had been excluded. Full thickness biopsies from the jejunum and mucosa biopsies from the duodenum and the jejunum were stained with a monoclonal antibody to Chlamydia lipopolysaccharide (LPS) and species-specific monoclonal antibodies to C. trachomatis and C. pneumoniae. We used polyclonal antibodies to chromogranin A, CD68, CD11c, and CD117 to identify enteroendocrine cells, macrophages, dendritic, and mast cells, respectively.ResultsChlamydia LPS was present in 89% of patients with IBS, but in only 14% of healthy controls (p < 0.001) and 79% of LPS-positive biopsies were also positive for C. trachomatis major outer membrane protein (MOMP). Staining for C. pneumoniae was negative in both patients and controls. Chlamydia LPS was detected in enteroendocrine cells of the mucosa in 90% of positive biopsies and in subepithelial macrophages in 69% of biopsies. Biopsies taken at different time points in 19 patients revealed persistence of Chlamydia LPS up to 11 years. The odds ratio for the association of Chlamydia LPS with presence of IBS (43.1; 95% CI: 13.2-140.7) is much higher than any previously described pathogenetic marker in IBS.ConclusionsWe found C. trachomatis antigens in enteroendocrine cells and macrophages in the small bowel mucosa of patients with IBS. Further studies are required to clarify if the presence of such antigens has a role in the pathogenesis of IBS.

Immune responses induced in mice vaccinated with Chlamydia trachomatis major outer membrane protein DNA connect with protein vaccine

Objective To research of immune responses induced in mouse vaccinated with Chlamydia trachomatis major outer membrane protein(MOMP) DNA and rMOMP protein.Methods Female BALB/c mice (3 to4 weeks old) divided into 5 groups,each group 12 mice.The mice were intramuscularly immunized with different antigens on three occasions,0,2 and 4 weeks.Two weeks after the last immunized,we measured immune responses induced in mice,the indexes were determined.The Chlamydiaspecific antibody titers in sera and vaginal washes,cytokine measurements,lymphocyte proliferation assay,the delayed hypersensitivity and vaginal swabs were collected and cultured for Chlamydia trachomatis after genital challenged and so on.Results The mice immunized with DNA and rMOMP.The result of Chlamydia-specific IgG is 0.629±0.052 (A405) and Chlamydia-specific IgA is 0.379±0.052 (A450);the stimulate index of lymphocyte proliferation assay is 5.682±0.484;the level of IFN-γ production by splenic lymphocytes is 1265±128.The results of mice immunized with MOMP DNA connect with rMOMP are better than other groups beside EB immunized mice.Conclusion Chlamydia trachomatis MOMP DNA connects with rMOMP vaccine can enhance protecting immune responses. Key words: Chlamydia trachomatis; DNA vaccine; rMOMP; Immune response

Scanning diagnostically significant antigenic regions of major Chlamydia Trachomatis protein MOMP using series of overlapping recombinant proteins

The amino acid sequence of the Chlamydia trachomatis major outer membrane protein (MOMP) has been modeled using a series of recombinant proteins containing MOMP fragments with lengths of 100 amino acids and overlaps of 30 amino acids. Testing of recombinant antigens in the immune enzyme analysis has shown that the proteins containing MOMP fragments of 191–286 and from 191–354 amino acids have had the greatest activity in the reaction with the anti-C. trachomatis-positive sera. The obtained data allow us to reach conclusions regarding the possibility of applying the presented recombinant proteins to develop a diagnostic test for detecting anti-C. trachomatis antibodies.

Protection against an intranasal challenge by vaccines formulated with native and recombinant preparations of the Chlamydia trachomatis major outer membrane protein

To compare the ability of a native and a recombinant preparation of the major outer membrane protein of Chlamydia trachomatis mouse pneumonitis (MoPn; Ct-nMOMP and Ct-rMOMP) to protect against an intranasal (i.n.) challenge, BALB/c mice were vaccinated by the intramuscular (i.m.) and subcutaneous (s.c.) routes using CpG-1826 and Montanide ISA 720 as adjuvants. Animals inoculated i.n. with live elementary bodies (EB) of Chlamydia served as a positive control. Negative control groups were immunized with either Neisseria gonorrhoeae recombinant porin B (Ng-rPorB) or with minimal essential medium (MEM-0). Mice immunized with Ct-rMOMP, Ct-nMOMP and EB developed a strong immune response as shown by high levels of Chlamydia specific antibodies in serum and a strong T-cell lymphoproliferative response. Following the i.n. challenge with 104 inclusion forming units (IFU) of C. trachomatis, mice immunized with Ct-nMOMP or Ct-rMOMP lost significantly less weight than the negative control animals immunized with Ng-rPorB or MEM-0 (P<0.05). However, mice vaccinated with the Ct-nMOMP lost less weight than those immunized with the Ct-rMOMP (P<0.05). Mice were euthanized at 10 days following the challenge, their lungs weighed and the number of IFU of Chlamydia determined. Based on the lung weight and number of IFU recovered, significant protection was observed in the groups of mice immunized with both Ct-nMOMP and the Ct-rMOMP (P<0.05). Nevertheless, significantly better protection was achieved with the Ct-nMOMP in comparison with the Ct-rMOMP (P<0.05). In conclusion, vaccination with a preparation of the nMOMP elicited a more robust protection than immunization with rMOMP, suggesting that the conformational structure of MOMP is critical for inducing strong protection.

Serovar-specific immune responses to peptides of variable regions of Chlamydia trachomatis major outer membrane protein in serovar D-infected women

The role of major outer membrane protein (MOMP) variable regions in the interaction of chlamydiae and host cells has been evaluated and their role in neutralization of antibodies has been clearly demonstrated. There are also studies that delineate the contribution of these regions to the cell-mediated immune response of the host and suggest that serovar E elicits serovar-specific immune responses in infected humans. However, further studies with other serovars are required to confirm these findings and to elucidate the role and importance of serovar-specific responses of variable regions of MOMP in other serovars. We, therefore, performed a detailed analysis of the humoral and cellular immune responses against the serovar D-specific variable segments (VS) of MOMP in women infected with Chlamydia trachomatis. We found that VS4 elicits significantly higher responses (both humoral and cellular) than other VS peptides (VS1, VS2 and VS3). VS4 elicited significantly higher (P < 0.0001) proliferative responses, interferon-gamma levels (P < 0.0001) as well as higher prevalence (P < 0.0001) of IgG antibodies against VS4 in serovar D-infected patients as compared to patients infected with other serovars, suggesting its role in serovar-specific immune responses.

Codon usage bias in Chlamydia trachomatis and the effect of codon modification in the MOMP gene on immune responses to vaccinationThis paper is one of a selection of papers in this Special Issue, entitled International Symposium on Recent Advances in Molecular, Clinical, and Social Medicine, and has undergone the Journal's usual peer-review process.

Chlamydia trachomatis is a kind of obligate intracellular bacterial pathogen that causes ocular and sexually transmitted diseases. In this study, we analyzed the codon usage patterns of the C. trachomatis mouse pneumonitis biovar (MoPn) and Homo sapiens. We found large differences between MoPn and human codon usages. To enhance the expression of Chlamydia protein in mammalian cells, the DNA sequence encoding the major outer-membrane protein (MOMP) of MoPn was modified to substitute the human-preferred codons for rarely used codons. The huma-optimized MOMP gene was synthesized and cloned into the pcDNA3 vector, as was the wild-type MOMP gene. The protein expression levels of the human-optimized MOMP and wild-type MOMP genes were compared. The experiments showed that the human-optimized MOMP gene produced significantly higher levels of MOMP protein than the wild-type MOMP, both in vitro and in vivo, but no obvious difference was observed in the levels of modified and native MOMP mRNA expression. The immunogenicity of the 2 constructs was examined using BALB/c mice following intramuscular immunization. The results showed that the mice immunized with the human-optimized MOMP produced higher levels of antigen-specific IgG antibody and showed stronger delayed-type hypersensitivity reactions and proliferative T cell responses than those immunized with the wild-type MOMP. Antigen-specific stimulation of spleen cells obtained from human MOMP DNA immunized mice produced higher levels of interferon-gamma than those obtained from wild-type MOMP DNA immunized mice. Taken together, the data show that human-optimized codon optimization can significantly enhance the gene expression and immunogenicity of the C. trachomatis MOMP DNA vaccine.

P1140 Immunoreactivity studies on synthetic peptides deriving from variable domain IV of Chlamydia trachomatis major outer membrane protein

P1140 Immunoreactivity studies on synthetic peptides deriving from variable domain IV of Chlamydia trachomatis major outer membrane protein

Immunization with the Chlamydia trachomatis major outer membrane protein, using adjuvants developed for human vaccines, can induce partial protection in a mouse model against a genital challenge

To test several vaccines for Chlamydia trachomatis we vaccinated BALB/c and C3H/HeN female mice with a purified preparation of the native mouse pneumonitis (MoPn) major outer membrane protein (MOMP). The MOMP was formulated with anyone of three different adjuvants MF59, LT-K63 or LT-R72. As a negative control the animals were immunized with ovalbumin. Positive controls were inoculated intranasally (i.n.) with 10 4 inclusion-forming units (IFU) of C. trachomatis MoPn. High levels of Chlamydia-specific antibodies were detected in the serum and vaginal washes of the mice immunized with MOMP. Using a lymphoproliferative assay (LPA) a significant response was obtained in splenocytes from most of the groups of mice vaccinated with MOMP. Two weeks after the last immunization the mice were challenged in the left ovarian bursa with 10 5 IFU of C. trachomatis MoPn and vaginal cultures were collected for a period of 6 weeks. Overall, BALB/c and C3H/HeN mice immunized with MOMP showed a decrease in the severity and length of the infection but the difference with the controls was not statistically significant. Following mating the percentage of mice with bilateral fertility was not significantly different between mice vaccinated with MOMP and their respective ovalbumin-immunized controls. However, the C3H/HeN mice immunized with MOMP using MF59 or LTR72 as adjuvants had significantly more embryos per mouse than the control groups. In conclusion, mice immunized with native MOMP and adjuvants developed for human vaccines showed significant Chlamydia-specific immune response and a limited protection against infection and long-term sequelae.

Isolation ofWaddlia malaysiensis, A Novel Intracellular Bacterium, from Fruit Bat (Eonycteris spelaea)

An obligate intracellular bacterium was isolated from urine samples from 7 (3.5%) of 202 fruit bats (Eonycteris spelaea) in peninsular Malaysia. The bacterium produced large membrane-bound inclusions in human, simian, and rodent cell lines, including epithelial, fibroblastlike, and lymphoid cells. Thin-section electron microscopy showed reticulate bodies dividing by binary fission and elementary bodies in the inclusions; mitochondria surrounded the inclusions. The inclusions were positive for periodic acid-Schiff stain but could not be stained by fluorescein-labeled anti-Chlamydia trachomatis major outer membrane protein monoclonal antibody. The bacterium was resistant to penicillin and streptomycin (MICs > 256 mg/L) but susceptible to tetracycline (MIC = 0.25 mg/L) and chloramphenicol (MIC = 0.5 mg/L). Sequence analysis of the 16SrRNA gene indicated that it was most closely related to 2 isolates of Waddlia chondrophila (94% and 96% identity). The 16S and 23S rRNA gene signatures were only 91% identical. We propose this novel bacterium be called W. malaysiensis.

Surface expression, single-channel analysis and membrane topology of recombinant Chlamydia trachomatis Major Outer Membrane Protein

BackgroundChlamydial bacteria are obligate intracellular pathogens containing a cysteine-rich porin (Major Outer Membrane Protein, MOMP) with important structural and, in many species, immunity-related roles. MOMP forms extensive disulphide bonds with other chlamydial proteins, and is difficult to purify. Leaderless, recombinant MOMPs expressed in E. coli have yet to be refolded from inclusion bodies, and although leadered MOMP can be expressed in E. coli cells, it often misfolds and aggregates. We aimed to improve the surface expression of correctly folded MOMP to investigate the membrane topology of the protein, and provide a system to display native and modified MOMP epitopes.ResultsC. trachomatis MOMP was expressed on the surface of E. coli cells (including "porin knockout" cells) after optimizing leader sequence, temperature and medium composition, and the protein was functionally reconstituted at the single-channel level to confirm it was folded correctly. Recombinant MOMP formed oligomers even in the absence of its 9 cysteine residues, and the unmodified protein also formed inter- and intra-subunit disulphide bonds. Its topology was modeled as a (16-stranded) β-barrel, and specific structural predictions were tested by removing each of the four putative surface-exposed loops corresponding to highly immunogenic variable sequence (VS) domains, and one or two of the putative transmembrane strands. The deletion of predicted external loops did not prevent folding and incorporation of MOMP into the E. coli outer membrane, in contrast to the removal of predicted transmembrane strands.ConclusionsC. trachomatis MOMP was functionally expressed on the surface of E. coli cells under newly optimized conditions. Tests of its predicted membrane topology were consistent with β-barrel oligomers in which major immunogenic regions are displayed on surface-exposed loops. Functional surface expression, coupled with improved understanding of MOMP's topology, could provide modified antigens for immunological studies and vaccination, including live subunit vaccines, and might be useful to co-express MOMP with other chlamydial membrane proteins.

Synthetic peptides based on Chlamydia trachomatis antigens identify cytotoxic T lymphocyte responses in subjects from a trachoma-endemic population.

CD8+ cytotoxic T lymphocytes (CTL) recognize peptide antigens in the context of class I MHC antigen molecules. To identify peptides capable of eliciting anti-Chlamydia trachomatis CTL responses, 13 synthetic peptides conforming to human leucocyte antigen (HLA)-B8- or -B35-predicted binding motifs were synthesized using sequences based on C. trachomatis major outer membrane protein (MOMP) and heat shock protein 60 (hsp60). Two of 11 HLA-B35-predicted binding peptides were able to stabilize HLA-B35 in an in vitro binding assay. All peptides were tested in CTL assays using peripheral blood mononuclear cells (PBMC) isolated from 26 HLA-B8 or -B35 individuals resident in a trachoma-endemic community. Responses to MOMP and hsp60 peptides were identified in a minority of both HLA-B8 and -B35 individuals. Two of 12 HLA-B8 subjects responded to MOMP and 1/13 to hsp60 peptides. Responses in HLA-B35 subjects were similar, 1/13 subjects responding to MOMP and 2/13 to hsp60 peptides. CTL responses were observed only in children resolving current infection and in adults without scarring of the conjunctiva. These results suggest that anti-chlamydial CTL occur at low levels in peripheral blood, but may be important in the resolution of naturally acquired human ocular chlamydial infection.

Genotyping of Chlamydia trachomatis strains from cultured isolates and nucleic acid amplification test-positive specimens

AbstractUrogenital strains of Chlamydia trachomatis are divided into several serogroups (D – K). Since these serovars are represented with differing prevalence in the population a serotyping of strains is necessary, when characterising the epidemiological situation. The aim of this study was the genotyping of C. trachomatis strains, the comparison of the results with those of serotyping, and the genotyping of positive specimens using commercial nucleic acid amplification tests (NAAT). The Chlamydia trachomatis major outer membrane protein gene (omp1) from 55 isolated strains and 36 NAAT-positive specimens was amplified by polymerase chain reaction (PCR). The restriction fragment length polymorphism (RFLP) patterns of these amplicons were compared with those of reference strains. The genotypes E and F were found to be most prevalent. The results are discussed considering other studies, genovariants and epidemiology.

Immunization with the Chlamydia trachomatis major outer membrane protein, using the outer surface protein A of Borrelia burgdorferi as an adjuvant, can induce protection against a chlamydial genital challenge

Two strains of mice C3H/HeN (H-2 k) and BALB/c (H-2 d) were immunized with the Chlamydia trachomatis mouse pneumonitis (MoPn) major outer membrane protein (MOMP) using the Borrelia burgdorferi outer surface protein A (OspA) as an adjuvant. As a control, groups of mice were inoculated with ovalbumin instead of MOMP. Female mice were immunized using three different routes: intramuscular (i.m.) plus subcutaneous (s.c.), intranasal (i.n.) and perivaginal and perisacral (p.vag.+p.sac.). Significant humoral and cell mediated immune responses developed particularly in mice inoculated by the i.m.+s.c. routes as determined by the levels of chlamydial specific antibody in the serum and genital secretions and a T-cell proliferative assay. Following immunization the animals were challenged in the genital tract with C. trachomatis MoPn and the course of the infection followed by vaginal cultures. Significant protection against infection was achieved in the C3H/HeN mice inoculated i.m.+s.c. with MOMP+OspA, as shown by the intensity and duration of vaginal cultures, and by the number of mice with positive cultures. On the other hand in BALB/c mice there was only a decrease in the number of animals with positive vaginal cultures. Six weeks after the challenge the mice were mated and the outcome of the pregnancy evaluated. In both the C3H/HeN and the BALB/c mice immunized i.m.+s.c. with MOMP+OspA there was significant protection against infertility as shown by the number of animals with bilateral fertility and number of embryos per uterine horn. In conclusion, immunization using C. trachomatis MOMP, and B. burgdorferi OspA as an adjuvant, can induce significant protection against a chlamydial genital challenge.

Design, expression and functional characterization of a synthetic gene encoding the Chlamydia trachomatis major outer membrane protein

A synthetic gene coding for the Chlamydia trachomatis serovar L2 major outer membrane protein (MOMP) was designed, constructed and expressed in Escherichia coli. The native amino acid sequence was reverse translated and the resulting nucleotide combinations manipulated in order to evenly distribute 25 unique restriction sites along the length of the gene while retaining the native amino acid sequence. The synthetic gene was cloned into a T7 promoter-controlled plasmid (pET-3a) and the expressed product was analyzed to assess antigenicity, cellular localization and function. Monoclonal antibodies specific for native MOMP reacted to the expressed product by immunoblot. Outer membrane fractionation confirmed that the processed protein was located in the outer membrane. MOMP expressed in E. coli and present in the outer membrane was shown to function as a general diffusion porin. This system provides the means to produce readily modifiable MOMP either in purified form or as a membrane-associated protein, and so facilitate the investigation of its functional, structural and antigenic properties.

Human Immunodeficiency Virus Type 1–Infected Women Exhibit Reduced Interferon‐γ Secretion afterChlamydia trachomatisStimulation of Peripheral Blood Lymphocytes

Epidemiologic, animal, and in vitro models suggest an important role for interferon (IFN)-gamma in the clearance of Chlamydia trachomatis infection. IFN-gamma in the supernatants of in vitro-stimulated peripheral blood mononuclear cells (PBMC) from 22 human immunodeficiency virus type 1 (HIV-1)-infected and 73 uninfected women at high risk for C. trachomatis acute pelvic inflammatory disease (PID) was studied. PBMC were stimulated with C. trachomatis purified major outer membrane protein (MOMP) and whole elementary bodies (EBs) from the 4 predominant serovars (E, F, K, and L2) that circulate in Nairobi. PBMC IFN-gamma secretion after stimulation with C. trachomatis EBs was significantly decreased in HIV-1-infected women. Among HIV-1-infected women, CD4 T cell depletion was associated with lower IFN-gamma secretion from PBMC stimulated with either C. trachomatis MOMP or EB antigen. Decreased antigen-specific IFN-gamma production may enhance the susceptibility of HIV-1-infected women to C. trachomatis PID.

Detection of Chlamydia trachomatis-specific antibodies in human sera by recombinant major outer-membrane protein polyantigens.

This study was performed to generate and evaluate recombinant antigens for use in a species-specific Chlamydia trachomatis immunoassay. In a molecular genetic approach, fragments of the C. trachomatis major outer-membrane protein (MOMP) were produced as fusion proteins to create three different constructs encompassing the variable domains I, II and IV of selected C. trachomatis serovars. The recombinant MOMP polyantigens were affinity-purified and used in an enzyme-linked immunosorbent assay. Antibody detection was evaluated with 103 patient sera and the results were compared with titres obtained in the micro-immunofluorescence test. The results showed that the generated MOMP polyantigens detected the presence of C. trachomatis-specific human antibodies with little cross-reaction to C. pneumoniae-specific antibodies. When compared to the micro-immunofluorescence assay the MOMP polyantigen detected the presence of anti-C. trachomatis IgG antibodies with a sensitivity of 80% and a specificity of 91%.

Different humoral immune response to Chlamydia trachomatis major outer membrane protein variable domains I and IV in Chlamydia-infected patients with or without reactive arthritis.

The possibility that some bacterial-specific factor(s) may play a role in triggering Chlamydia trachomatis reactive arthritis was investigated. Since the variable domains of the major outer membrane protein (MOMP) contain the serovar-determining epitopes of C. trachomatis, the ability of serum IgG to recognize peptides mimicking these epitopes was determined in 2 groups of infected patients, one with and the other without reactive arthritis. Because asymptomatic C. trachomatis infections are frequent, and nonspecific reactions due to inflammation could be observed, this study was also performed with samples from healthy blood donors and from patients with inflammatory arthritis unrelated to C. trachomatis infection. A predominant reactivity against peptides duplicating the J serovar-specific epitopes was only observed in the group of patients with reactive arthritis. For positive samples, differences between the two groups of C. trachomatis-infected patients were clearly observed. The mean numbers of positive responses obtained for each of the 7 peptides of the MOMP domain I or each of the 8 peptides of the MOMP domain IV were significantly higher for samples from patients with reactive arthritis (4.7 and 6) than for those from patients with only C. trachomatis urogenital infection (1.3 and 2.9). Patients with reactive arthritis had a pattern of reactivities that was compatible with infection by several serotypes of bacteria. Repeated exposures to C. trachomatis might therefore be involved in the development of the disease.

Vaccination of mice with DNA plasmids coding for the Chlamydia trachomatis major outer membrane protein elicits an immune response but fails to protect against a genital challenge

A DNA plasmid encoding the gene of the major outer membrane protein (MOMP) of the Chlamydia trachomatis mouse pneumonitis (MoPn) serovar and three plasmids containing the variable domains (VD) of the MOMP were constructed. Female mice were inoculated with the plasmids and 60 days later were challenged in the genital tract with C. trachomatis. Six weeks after challenge female mice were caged with male mice and the course of the mating followed. Mice immunized with the MOMP plasmids mounted weak humoral and cell mediated immune responses. However, following the genital challenge no significant differences in vaginal shedding were observed between the groups immunized with the MOMP and control plasmids. In addition, the fertility rates were similar in the experimental and negative control groups. In conclusion, vaccination with DNA plasmids encoding the MOMP elicited a modest immune response but did not protect against infection or disease.