Chlamydial disease pathogenesis. The 57-kD chlamydial hypersensitivity antigen is a stress response protein

Evaluation of Four Adjuvant Combinations, IVAX-1, IVAX-2, CpG-1826+Montanide ISA 720 VG and CpG-1018+Montanide ISA 720 VG, for Safety and for Their Ability to Elicit Protective Immune Responses in Mice against a Respiratory Challenge with Chlamydia muridarum

There is an urgent need to produce a vaccine for Chlamydia trachomatis infections. Here, using the Chlamydia muridarum major outer membrane protein (MOMP) as an antigen, four adjuvant combinations IVAX-1 (MPLA+CpG-1018+AddaVax), IVAX-2 (MPLA+CpG-1018+AS03), CpG-1826+Montanide ISA 720 VG (CpG-1826+Mont) and CpG-1018+Montanide ISA 720 VG (CpG-1018+Mont), were tested for their local reactogenicity and ability to elicit protection in BALB/c mice against a respiratory challenge with C. muridarum. Immunization with IVAX-1 or IVAX-2 induced no significant local reactogenicity following intramuscular immunization. In contrast, vaccines containing Montanide resulted in the formation of a local granuloma. Based on the IgG2a/IgG1 ratio in serum, the four adjuvant combinations elicited Th1-biased responses. IVAX-1 induced the highest in vitro neutralization titers while CpG-1018+Mont stimulated the lowest. As determined by the levels of IFN-γ produced by T-cells, the most robust cellular immune responses were elicited in mice immunized with CpG-1018+Mont, while the weakest responses were mounted by mice receiving IVAX-1. Following the respiratory challenge, mice immunized with CpG-1018+Mont lost the least amount of body weight and had the lowest number of C. muridarum inclusion-forming units (IFUs) in the lungs, while those receiving IVAX-2 had lost the most weight and had the highest number of IFUs in their lungs. Animals vaccinated with CpG-1826+Mont had the lightest lungs while those immunized using IVAX-2 had the heaviest. To conclude, due to their safety and adjuvanticity, IVAX formulations should be considered for inclusion in human vaccines against Chlamydia.

Problems with Understanding Chlamydia trachomatis Immunology

The pay off for understanding Chlamydia. trachomatis (CT) immunology is the development of a vaccine. Two lines of research have contributed to our current understanding of CT immunology. The first is the Grayston model of type specific immunity and genus specific pathology which was elaborated by Caldwell and Morrison as the major outer membrane protein (MOMP) and heat shock protein 60 (HSP60) paradigm. The second is the murine model of C. muridarum (CM) infection which established the essential role of major histocompatibility complex class II and CD4 T cells in immunity. However neither approach has yielded a vaccine. I review these two lines of research and conclude with six problem areas in human CT immunology whose resolution may result in a vaccine.(122 words)

Vaccination with the recombinant major outer membrane protein elicits long-term protection in mice against vaginal shedding and infertility following a Chlamydia muridarum genital challenge

Implementation of a vaccine is likely the best approach to curtail Chlamydia trachomatis infections. The aim of this study was to determine the ability of a vaccine formulated with the recombinant major outer membrane protein (MOMP) and Th1 and Th2 adjuvants, delivered by combinations of systemic and mucosal routes, to elicit long-term protection in mice against a genital challenge with Chlamydia muridarum. As a negative control, mice were vaccinated with the recombinant Neisseria gonorrhoeae porinB, and the positive control group was immunized with C. muridarum live elementary bodies (EB). The four vaccines formulated with MOMP, as determined by the titers of IgG and neutralizing antibodies in serum, proliferative responses of T-cells stimulated with EB and levels of IFN-γ in the supernatants, elicited robust humoral and cellular immune responses over a 6-month period. Groups of mice were challenged genitally at 60, 120, or 180 days postimmunization. Based on the number of mice with positive vaginal cultures, number of positive cultures, length of time of shedding, and number of inclusion forming units recovered, MOMP vaccinated groups were significantly protected. To assess fertility, when the vaginal cultures became negative, female mice were caged with male mice and the outcome of the pregnancy evaluated. As determined by the number of pregnant mice and the number of embryos, two of the vaccine formulations protected mice up to 180 days postimmunization. To our knowledge this is the first subunit of Chlamydia vaccine that has elicited in mice significant long-term protection against a genital challenge.

Improved protection against Chlamydia muridarum using the native major outer membrane protein trapped in Resiquimod-carrying amphipols and effects in protection with addition of a Th1 (CpG-1826) and a Th2 (Montanide ISA 720) adjuvant

A new vaccine formulated with the Chlamydia muridarum native major outer membrane protein (nMOMP) and amphipols was assessed in an intranasal (i.n.) challenge mouse model. nMOMP was trapped either in amphipol A8-35 (nMOMP/A8-35) or in A8-35 conjugated with Resiquimod (nMOMP/Resiq-A8-35), a TLR7/8 agonist added as adjuvant. The effects of free Resiquimod and/or additional adjuvants, Montanide ISA 720 (TLR independent) and CpG-1826 (TLR9 agonist), were also evaluated. Immunization with nMOMP/A8-35 alone administered i.n. was used as negative adjuvant-control group, whereas immunizations with C. muridarum elementary bodies (EBs) and MEM buffer, administered i.n., were used as positive and negative controls, respectively. Vaccinated mice were challenged i.n. with C. muridarum and changes in body weight, lungs weight and recovery of Chlamydia from the lungs were evaluated. All the experimental groups showed protection when compared with the negative control group. Resiquimod alone produced weak humoral and cellular immune responses, but both Montanide and CpG-1826 showed significant increases in both responses. The addition of CpG-1826 alone switched immune responses to be Th1-biased. The most robust protection was elicited in mice immunized with the three adjuvants and conjugated Resiquimod. Increased protection induced by the Resiquimod covalently linked to A8-35, in the presence of Montanide and CpG-1826 was established based on a set of parameters: (1) the ability of the antibodies to neutralize C. muridarum; (2) the increased proliferation of T-cells in vitro accompanied by higher production of IFN-γ, IL-6 and IL-17; (3) the decreased body weight loss over the 10 days after challenge; and (4) the number of IFUs recovered from the lungs at day 10 post challenge. In conclusion, a vaccine formulated with the C. muridarum nMOMP bound to amphipols conjugated with Resiquimod enhances protective immune responses that can be further improved by the addition of Montanide and CpG-1826.

Update on Chlamydia trachomatis Vaccinology

Attempts to produce a vaccine to protect against Chlamydia trachomatis-induced trachoma were initiated more than 100 years ago and continued for several decades. Using whole organisms, protective responses were obtained. However, upon exposure to C. trachomatis, disease exacerbation developed in some immunized individuals, precluding the implementation of the vaccine. Evidence of the role of C. trachomatis as a sexually transmitted pathogen started to emerge in the 1960s, and it soon became evident that it can cause acute infections and long-term sequelae in women, men, and newborns. The main focus of this minireview is to summarize recent findings and discuss formulations, including antigens, adjuvants, routes, and delivery systems for immunization, primarily explored in the female mouse model, with the goal of implementing a vaccine against C. trachomatis genital infections.

Immunopathogenesis of Chlamydial Infections

Chlamydial infections lead to a number of clinically relevant diseases and induce significant morbidity in human populations. It is generally understood that certain components of the host immune response to infection also mediate such disease pathologies. A clear understanding of pathogenic mechanisms will enable us to devise better preventive and/or intervention strategies to mitigate the morbidity caused by these infections. Over the years, numerous studies have been conducted to explore the immunopathogenic mechanisms of Chlamydia-induced diseases of the eye, reproductive tract, respiratory tract, and cardiovascular systems. In this article, we provide an overview of the diseases caused by Chlamydia, animal models used to study disease pathology, and a historical context to the efforts to understand chlamydial pathogenesis. Furthermore, we discuss recent findings regarding pathogenesis, with an emphasis on the role of the adaptive immune response in the development of chlamydial disease sequelae. Finally, we summarize the key insights obtained from studies of chlamydial pathogenesis and avenues that remain to be explored in order to inform the next steps of vaccine development against chlamydial infections.

A re-evaluation of the role of B cells in protective immunity to Chlamydia infection

Chlamydia trachomatis is the etiological agent of the most commonly reported bacterial sexual transmitted infection (STI) in North America and Europe. The control of Chlamydia infection is hindered by the asymptomatic nature of initial infection but the consequence of untreated infection seriously threatens the reproductive health of young women. Unfortunately, there is no licensed vaccine for Chlamydia vaccine, in part due to our incomplete understanding of the immune response to Chlamydia urogenital infection. It has been well established that T cell-mediated immunity plays a dominant role in protective immunity against Chlamydia and thus the importance of B cells is somewhat underappreciated. Here, we summarize recent progress on understanding the role of B cells during Chlamydia genital tract infections and discuss how B cells and humoral immunity make an effective contribution to host defense against important intracellular pathogens, including Chlamydia.

Transcriptional profiling of human epithelial cells infected with plasmid-bearing and plasmid-deficient Chlamydia trachomatis

Chlamydia trachomatis is an obligate intracellular epitheliotropic bacterial pathogen of humans. Infection of the eye can result in trachoma, the leading cause of preventable blindness in the world. The pathophysiology of blinding trachoma is driven by multiple episodes of reinfection of conjunctival epithelial cells, producing an intense chronic inflammatory response resulting in submucosal tissue remodeling and scarring. Recent reports have shown that infection with trachoma organisms lacking the cryptic chlamydial plasmid is highly attenuated in macaque eyes, a relevant experimental model of human trachoma infection. To better understand the molecular basis of plasmid-mediated infection attenuation and the potential modulation of host immunity, we conducted transcriptional profiling of human epithelial cells infected with C. trachomatis plasmid-bearing (A2497) and plasmid-deficient (A2497P(-)) organisms. Infection of human epithelial cells with either strain increased the expression of host genes coding for proinflammatory (granulocyte-macrophage colony-stimulating factor [GM-CSF], macrophage colony-stimulating factor [MCSF], interleukin-6 [IL-6], IL-8, IL-1α, CXCL1, CXCL2, CXCL3, intercellular adhesion molecule 1 [ICAM1]), chemoattraction (CCL20, CCL5, CXCL10), immune suppression (PD-L1, NFKB1B, TNFAIP3, CGB), apoptosis (CASP9, FAS, IL-24), and cell growth and fibrosis (EGR1 and IL-20) proteins. Statistically significant increases in the levels of expression of many of these genes were found in A2497-infected cells compared to the levels of expression in A2497P(-)-infected cells. Our findings suggest that the chlamydial plasmid plays a focal role in the host cell inflammatory response to infection and immune avoidance. These results provide new insights into the role of the chlamydial plasmid as a chlamydial virulence factor and its contributions to trachoma pathogenesis.

Whole genome identification of C. trachomatis immunodominant antigens after genital tract infections and effect of antibiotic treatment of pigtailed macaques

The cervix and/or fallopian tubes of pigtailed macaques were experimentally infected with Chlamydia trachomatis. Their sera were collected at varying time points and screened for identification of immunodominant antigens using a whole-genome protein microarray. The effect of doxycycline treatment on the antibody response generated in these macaques was also investigated. Twenty-five female macaques were infected with C. trachomatis serovars D or E in the cervix and/or fallopian tubes. Bloods were collected at baseline and at various intervals after challenge. Serum samples were tested for antibodies using a C. trachomatis serovar D protein microarray. Twenty chlamydial antigens reacted with sera from at least 68% (17/25) of the macaques. In addition to some well-known chlamydial antigens, nine different proteins, not previously recognized as immunodominant, including four hypothetical proteins (CT005, CT066, CT360 and CT578), were identified. Monkeys infected in the fallopian tubes developed a more robust antibody response than animals inoculated in the cervix. Treatment with doxycycline significantly decreased Chlamydia-specific antibody levels. In summary, using protein microarray serum samples from experimentally infected pigtailed macaques were screened for immunodominant chlamydial antigens. These antigens can now be tested in animal models for their ability to protect and as markers of disease progression.

BIOLOGICAL SIGNIFICANCE

This is the first time that Chlamydia trachomatis immunodominant antigens have been identified in pigtailed macaques following a uterine cervix or a fallopian tubes infection. These immunodominant antigens can now be used to vaccinate non-human primates and determine their ability to protect against a C. trachomatis genital infection. Proteins that are protective can subsequently be tested in humans. Amongst the immunodominant antigens some were predominantly recognized by sera from macaques inoculated in the fallopian tubes rather than in the cervix and therefore, may be markers for upper genital tract pathology. In addition, treatment with doxycycline following infection significantly decreased Chlamydia-specific antibody levels. This information can be used to evaluate the efficacy of antibiotic treatment and potentially susceptibility to reinfection.

Increased immunoaccessibility of MOMP epitopes in a vaccine formulated with amphipols may account for the very robust protection elicited against a vaginal challenge with Chlamydia muridarum

There is a need to implement a vaccine to protect against Chlamydia trachomatis infections. To test a new vaccine, mice were immunized with the Chlamydia muridarum native major outer membrane protein (nMOMP) solubilized with either amphipol A8-35 or the detergent Z3-14. OVA was used as a negative control, and mice were inoculated intranasally with C. muridarum as positive controls. Animals vaccinated with nMOMP mounted strong Chlamydia-specific humoral and cell-mediated immune responses. Mice vaccinated with nMOMP/A8-35 had a higher ratio of Abs to denatured elementary bodies (EB) over live EB, recognized more synthetic MOMP peptides and had higher neutralizing titers than sera from mice immunized with nMOMP/Z3-14. T cell lymphoproliferative responses and levels of IFN-γ were also higher in mice vaccinated with nMOMP/A8-35 than with nMOMP/Z3-14. Following immunization, animals were challenged intravaginally with C. muridarum. On the basis of the number of mice with positive vaginal cultures, length of vaginal shedding, total number of positive vaginal cultures, and number of Chlamydia inclusion forming units recovered, nMOMP/A8-35 elicited a more robust protection than nMOMP/Z3-14. By depleting T cells with Abs, we determined that CD4(+) and not CD8(+) T cells mediated the protection elicited by nMOMP/A8-35. Mice were subsequently mated, and based on the number of pregnant mice and number of embryos, animals that were vaccinated with nMOMP/A8-35 or nMOMP/Z3-14 had fertility rates equivalent to the positive control group immunized with live EB and the fertility controls. In conclusion, increased accessibility of epitopes in the nMOMP/A8-35 preparation may account for the very robust protection against infection and disease elicited by this vaccine.

Vaccination with the recombinant major outer membrane protein elicits antibodies to the constant domains and induces cross-serovar protection against intranasal challenge with Chlamydia trachomatis

To determine the ability of the major outer membrane protein (MOMP) to elicit cross-serovar protection, groups of mice were immunized by the intramuscular (i.m.) and subcutaneous (s.c.) routes with recombinant MOMP (rMOMP) from Chlamydia trachomatis serovars D (UW-3/Cx), E (Bour), or F (IC-Cal-3) or Chlamydia muridarum strain Nigg II using CpG-1826 and Montanide ISA 720 VG as adjuvants. Negative-control groups were immunized i.m. and s.c. with Neisseria gonorrhoeae recombinant porin B (Ng-rPorB) or i.n. with Eagle's minimal essential medium (MEM-0). Following vaccination, the mice developed antibodies not only against the homologous serovar but also against heterologous serovars. The rMOMP-vaccinated animals also mounted cell-mediated immune responses as assessed by a lymphoproliferative assay. Four weeks after the last immunization, mice were challenged i.n. with 10(4) inclusion-forming units (IFU) of C. muridarum. The mice were weighed for 10 days and euthanized, and the number of IFU in their lungs was determined. At 10 days postinfection (p.i.), mice immunized with the rMOMP of C. muridarum or C. trachomatis D, E, or F had lost 4%, 6%, 8%, and 8% of their initial body weight, respectively, significantly different from the negative-control groups (Ng-rPorB, 13%; MEM-0, 19%; P < 0.05). The median number of IFU recovered from the lungs of mice immunized with C. muridarum rMOMP was 0.13 × 10(6). The median number of IFU recovered from mice immunized with rMOMP from serovars D, E, and F were 0.38 × 10(6), 7.56 × 10(6), and 11.94 × 10(6) IFU, respectively. All the rMOMP-immunized animals had significantly less IFU than the Ng-rPorB (40 × 10(6))- or MEM-0 (70 × 10(6))-immunized mice (P < 0.05). In conclusion, vaccination with rMOMP can elicit protection against homologous and heterologous Chlamydia serovars.

Trachoma: protective and pathogenic ocular immune responses to Chlamydia trachomatis

Trachoma, caused by Chlamydia trachomatis (Ct), is the leading infectious blinding disease worldwide. Chronic conjunctival inflammation develops in childhood and leads to eyelid scarring and blindness in adulthood. The immune response to Ct provides only partial protection against re-infection, which can be frequent. Moreover, the immune response is central to the development of scarring pathology, leading to loss of vision. Here we review the current literature on both protective and pathological immune responses in trachoma. The resolution of Ct infection in animal models is IFNγ-dependent, involving Th1 cells, but whether this is the case in human ocular infection still needs to be confirmed. An increasing number of studies indicate that innate immune responses arising from the epithelium and other innate immune cells, along with changes in matrix metalloproteinase activity, are important in the development of tissue damage and scarring. Current trachoma control measures, which are centred on repeated mass antibiotic treatment of populations, are logistically challenging and have the potential to drive antimicrobial resistance. A trachoma vaccine would offer significant advantages. However, limited understanding of the mechanisms of both protective immunity and immunopathology to Ct remain barriers to vaccine development.

Immune Sensitization to the 60 kD Heat Shock Protein and Pregnancy Outcome

Heat shock proteins are highly conserved proteins present in organisms ranging from bacteria to man. They are both dominant microbial immunogens and among the first proteins produced during mammalian embryo development. Since bacterial and human heat shock proteins share a high degree of amino acid sequence homology, it has been suggested that sensitization to bacterial heat shock proteins during an infection may result in autoimmunity to human heat shock proteins. Infertile couples seeking in vitro fertilization (IVF) may have been previously sensitized to bacterial heat shock proteins as a consequence of an asymptomatic upper genital tract infection. Due to daily clinical monitoring and precisely timed fertilization these patients are an ideal study group to investigate the effect of prior sensitization to heat shock proteins on preimplantation embryo development and implantation failure. Immune sensitization at the level of the cervix to the 60 kD heat shock protein (hsp60) has been associated with implantation failure in some IVF patients. Similarly, the highest prevalence of circulating hsp60 antibodies among IVF patients was found in the sera of women whose embryos failed to develop in vitro. To more directly assess whether humoral immunity to hsp60 influenced in vitro embryo development, a mouse embryo culture model was established. Monoclonal antibody to mammalian hsp60 markedly impaired mouse embryo development in vitro. These data suggest that immune sensitization to human hsp60, possibly developed as a consequence of infection, may adversely affect pregnancy outcome in some patients.

Chlamydia trachomatis Infection, Immunity, and Pregnancy Outcome

Chlamydia trachomatis can ascend from the cervix to the fallopian tubes and survive for long periods of time without causing symptoms. The immune response to infection clears the extracellular organisms but leads to development of a persistent intracellular infection. Repeated cycles of productive infection and persistence eventually induce tubal occlusion and infertility. Persistently infected cells continue to synthesize the chlamydial 60 kD heat shock protein (hsp60). Immunity to conserved regions of hsp60 may result in autoimmunity to human hsp60. Expression of hsp60 by the embryo and decidua during early pregnancy may reactivate hsp60-sensitized lymphocytes, disturb pregnancy-induced immune regulatory mechanisms, and lead to immune rejection of the embryo. Due to this mechanism women with tubal infertility who are sensitized to the human hsp60 may have a decreased probability of successful outcome after undergoing in vitro fertilization and embryo transfer.

Serum interleukin-1β, interleukin-8 and anti-heat shock 60 Chlamydia trachomatis antibodies as markers of ectopic pregnancy

Anti-Chlamydial trachomatis (anti-CT) responses, particularly anti-heat shock 60 (Hsp60), antibodies confer a higher risk of ectopic pregnancy. With emerging evidence supporting the pivotal role of interleukin-1β (IL-1β) and IL-8 in the immunopathogenesis of CT-specific tubal obstruction, we determined anti-CT Hsp60 antibody reactivity and serum concentrations of IL-1β and IL-8 in failed pregnancies consisting of 30 consecutive ectopic pregnancies and 30 missed abortions, with 32 viable intrauterine pregnancies tested as normal controls. ELISAs were utilised to measure IgA or IgG anti-CT major outer membrane outer protein (MOMP) antibodies, IgG anti-CT Hsp60 antibodies and IL-1β and IL-8. IgG anti-CT Hsp60 antibodies were more prevalent in ectopic pregnancy cases (43.3%, 13/30) than in intrauterine pregnancies (16%, 5/32, p=0.016). All 13 ectopic pregnancy anti-CT Hsp60-positive cases had anti-CT MOMP antibodies. CT-specific antibodies were more frequent in merged ectopic pregnancy and missed abortions cases (35%, 21/60) than in intrauterine pregnancies (16%, p=0.049). The median (range) levels of IL-1β in ectopic pregnancy, missed abortions and normal intrauterine pregnancies were 1.74 (0.2-8.7), 1.14 (0.2-16) and 1.22 (0.2-16.2) pg/ml, respectively (p>0.05, for all). Serum IL-8 levels were comparable amongst groups: ectopic pregnancy (median [range]: 25.1 [18.3-1000]); missed abortions (32.9 [15.39-1000]); and intrauterine pregnancies (25.11 [18.3-1000] pg/ml). Anti-CT antibody-positive ectopic pregnancy had significantly lower IL-1β levels (1.29 [0.2-2.93]) pg/ml than sero-negative ectopic pregnancy cases (2.09 [1.10-8.70]) pg/ml, (p=0.022), but IL-8 did not differ. Our data demonstrate that anti-CT Hsp60 immunity is a predominant feature of ectopic pregnancy. We conclude that neither IL-1β nor IL-8 can be considered markers of failed pregnancy, although lower levels of the former cytokine are associated with CT-related ectopic pregnancy.

Amphipols stabilize the Chlamydia major outer membrane protein and enhance its protective ability as a vaccine

The native major outer membrane protein (nMOMP) from Chlamydia was purified in its trimeric form using the zwitterionic detergent Z3-14. In aliquots from this preparation, Z3-14 was exchanged for amphipol (APol) A8-35. CD analysis showed that trapping with A8-35 improved the thermostability of nMOMP without affecting its secondary structure. Recombinant MOMP (rMOMP) was also formulated with Z3-14 or A8-35. Four groups of mice were vaccinated with nMOMP/Z3-14, nMOMP/A8-35, rMOMP/Z3-14 or rMOMP/A8-35 using CpG and Montanide as adjuvants. A positive control group was inoculated intranasally with live Chlamydia and a negative control group with culture medium. Mice were challenged intranasally with live Chlamydia and protection was assessed based on changes in body weight, the weight of the lungs and the number of chlamydial inclusion forming units recovered from the lungs 10 days after the challenge. Overall, vaccines formulated with nMOMP elicited better protection than those using rMOMP. Furthermore, the protection afforded by nMOMP/A8-35 was more robust than that achieved with nMOMP/Z3-14. In contrast, no differences in protection were observed between rMOMP/Z3-14 and rMOMP/A8-35 preparations. These findings suggest that the higher protection conferred by nMOMP/A8-35 complexes most likely results from a better preservation of the native structure of MOMP and/or from a more efficient presentation of the antigen to the immune system, rather than from an adjuvant effect of the amphipol. Thus, amphipols can be used in vaccine formulations to stabilize a membrane-protein component and enhance its immunogenicity.

Identification of immunodominant antigens by probing a whole Chlamydia trachomatis open reading frame proteome microarray using sera from immunized mice

Chlamydia trachomatis infections can lead to severe chronic complications, including trachoma, ectopic pregnancy, and infertility. The only effective approach to disease control is vaccination. The goal of this work was to identify new potential vaccine candidates through a proteomics approach. We constructed a protein chip array (Antigen Discovery, Inc.) by expressing the open reading frames (ORFs) from C. trachomatis mouse pneumonitis (MoPn) genomic and plasmid DNA and tested it with serum samples from MoPn-immunized mice. Two groups of BALB/c female mice were immunized either intranasally or intravaginally with live elementary bodies (EB). Another two groups were immunized by a combination of the intramuscular and subcutaneous routes with UV-treated EB (UV-EB), using either CpG and Montanide as adjuvants to favor a Th1 response or alum to elicit a Th2 response. Serum samples collected at regular intervals postimmunization were tested in the proteome array. The microarray included the expression products of 909 proteins from a total of 921 ORFs of the Chlamydia MoPn genome and plasmid. A total of 185 immunodominant proteins elicited an early and sustained antibody response in the mice immunized with live EB, and of these, 71 were also recognized by the sera from mice immunized with UV-EB. The reactive antigens included some proteins that were previously described as immunogenic, such as the major outer membrane protein, OmpB, Hsp60, and IncA and proteins from the type III secretion system. In addition, we identified in mice several new immunogens, including 75 hypothetical proteins. In summary, we have identified a new group of immunodominant chlamydial proteins that can be tested for their ability to induce protection.

DnaK and GroEL are induced in response to antibiotic and heat shock in Acinetobacter baumannii

We studied the expression of DnaK and GroEL in Acinetobacter baumannii cells (strains ATCC 19606 and RS4) under stress caused by heat shock or antibiotics. A Western blot assay showed that DnaK and GroEL levels increased transiently more than 2-fold after exposure of bacterial cells to heat shock for 20 min at 50 °C. Heat induction of DnaK and GroEL was blocked completely when an inhibitor of transcription, rifampicin, was added 1 min before a temperature upshift to 50 °C, suggesting that the induction of these chaperones depends on transcription. A. baumannii cells pretreated at 45 °C for 30 min were better able to survive at 50 °C for 60 min than cells pretreated at 37 °C, indicating that A. baumannii is able to acquire thermotolerance. DnaK and GroEL were successfully induced in cells pre-incubated with a subinhibitory concentration of streptomycin. Moreover, bacterial cells pretreated for 30 min at 45 °C were better able to survive streptomycin exposure than cells pretreated at physiological temperatures. DnaK expression was upregulated in a multidrug-resistant strain of A. baumannii (RS4) in the presence of different antimicrobials (ampicillin+sulbactam, cefepime, meropenem and sulphamethoxazole+trimethoprim). This study is to the best of our knowledge the first to show that A. baumannii DnaK and GroEL could play an important role in the stress response induced by antibiotics.

Pregnancy outcome following pelvic infection

To determine whether a previous pelvic infection has an effect on the outcome of a subsequent pregnancy, we identified women with a diagnosis of pelvic inflammatory disease (PID), amnionitis, and postpartum or postabortal endometritis-salpingitis by a retrospective chart review of all patients admitted to the Department of Obstetrics and Gynecology at The New York Hospital-Cornell Medical Center between 1975 and 1977 and between 1985 and 1988. Antimicrobial regimens effective against Chlamydia trachomatis were initiated in 1985. Controls were randomly selected patients presenting during the same time period for routine examinations who had normal Pap smears and no infections. Both groups were comparable for age, race, gravity, and parity. Differences were evaluated by chi square analysis, using the Yates correction factor. We identified 183 women with a history of the above infections who subsequently conceived, and 82 controls. There were no differences in outcome between the two index groups. Term vaginal deliveries occurred in 14.2% of the women with a prior pelvic infection and in 56% of the controls (P < 0.001). Among the 97 women who had had PID, 21 (21.6%) had a spontaneous abortion in the subsequent pregnancy, as opposed to 6 (7.3%) of the controls (P = 0.013). In addition, eight of the women with PID (but no controls) went into preterm labor (P = 0.021). An increased incidence of preterm labor (P = 0.001) was also observed in women with a history of amnionitis. A history of endometritis was not associated with an increased prevalence of abnormal outcome in subsequent pregnancies. PID and amnionitis may adversely affect the outcome of subsequent pregnancies.

History and physiology of immune privilege

Immune privilege is the condition in which selected immune responses are suppressed or excluded in certain organs, such as the eye. Immune privilege in the eye was described over 130 years ago, but its significance was not appreciated until the early 1950s. Investigations beginning in the 1970s ushered in a new era and revealed that ocular immune privilege is due to anatomical, physiological, and immunoregulatory processes that prevent the induction and expression of immune-mediated inflammation. It is widely believed that immune privilege is an adaptation for reducing immune-mediated injury to ocular cells that have limited or no capacity for regeneration.

Identification of Chlamydia trachomatis outer membrane complex proteins by differential proteomics

The extracellular chlamydial infectious particle, or elementary body (EB), is enveloped by an intra- and intermolecular cysteine cross-linked protein shell called the chlamydial outer membrane complex (COMC). A few abundant proteins, including the major outer membrane protein and cysteine-rich proteins (OmcA and OmcB), constitute the overwhelming majority of COMC proteins. The identification of less-abundant COMC proteins has been complicated by limitations of proteomic methodologies and the contamination of COMC fractions with abundant EB proteins. Here, we used parallel liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analyses of Chlamydia trachomatis serovar L2 434/Bu EB, COMC, and Sarkosyl-soluble EB fractions to identify proteins enriched or depleted from COMC. All well-described COMC proteins were specifically enriched in the COMC fraction. In contrast, multiple COMC-associated proteins found in previous studies were strongly enriched in the Sarkosyl-soluble fraction, suggesting that these proteins are not COMC components or are not stably associated with COMC. Importantly, we also identified novel proteins enriched in COMC. The list of COMC proteins identified in this study has provided reliable information for further understanding chlamydial protein secretion systems and modeling COMC and EB structures.

Two chaperonin systems in bacterial genomes with distinct ecological roles

Bacterial chaperonins are essential to cell viability and have a role in endosymbiosis, which leads to increased biological complexity. However, the extent to which chaperonins promote ecological innovation is unknown. We screened 622 bacterial genomes for genes encoding chaperonins, and found archaeal-like chaperonins in bacteria that inhabit archaeal ecological niches. We found that chaperonins encoded in pathogenic bacteria are the most functionally divergent. We identified the molecular basis of the dramatic structural changes in mitochondrial GROEL, a highly derived chaperonin gene. Our analysis suggests that chaperonins are important capacitors of evolutionary and ecological change.

Chlamydia vaccine candidates and tools for chlamydial antigen discovery

The failure of the inactivated Chlamydia-based vaccine trials in the 1960s has led researchers studying Chlamydia to take cautious and rational approaches to develop safe and effective chlamydial vaccines. Subsequent research efforts focused on three areas. The first is the analysis of the immunobiology of chlamydial infection in animal models, with supporting clinical studies, to identify the immune correlates of both protective immunity and pathological responses. Second, recent radical improvements in genomics, proteomics and associated technologies have assisted in the implementation of creative approaches to search for suitable vaccine candidates. Third, progress in the analysis of host response and adjuvanticity regulating both innate and adaptive immunity at the mucosal site of infection has led to progress in the design of optimal delivery and adjuvant systems for enhancing protective immunity. Considerable progress has been made in the first two areas but research efforts to better define the factors that regulate immunity at mucosal sites of infection and to develop strategies to boost protective immunity via immunomodulation, effective delivery systems and potent adjuvants, have remained elusive. In this article, we will summarize progress in these areas with a focus on chlamydial vaccine antigen discovery, and discuss future directions towards the development of a safe and effective chlamydial vaccine.

Chronic infection in the etiology of atherosclerosis--the case for Chlamydia pneumoniae

Established cardiovascular risk factors do not fully explain the variations in the prevalence and severity of coronary heart disease. Recent evidence suggests that common chronic infections may contribute, either by direct or indirect mechanisms, to the etiology and/or progression of coronary atherosclerosis. Of the candidate infectious agents implicated, Chlamydia pneumoniae has emerged as the most likely pathogen to have a causal role. Evidence for this is based on seroepidemiologic, pathologic, and laboratory-based evidence, in addition to recent small-scale antibiotic intervention studies. Concerted efforts are now focused on the design of large prospective trials with antibiotics active against C. pneumoniae in the secondary prevention of coronary heart disease.

Structural basis for activation and inhibition of the secreted chlamydia protease CPAF

The obligate intracellular pathogen Chlamydia trachomatis is the most common cause of sexually transmitted bacterial disease. It secretes a protease known as chlamydial protease/proteasome-like activity factor (CPAF) that degrades many host molecules and plays a major role in Chlamydia pathogenesis. Here, we show that mature CPAF is a homodimer of the catalytic domains, each of which comprises two distinct subunits. Dormancy of the CPAF zymogen is maintained by an internal inhibitory segment that binds the CPAF active site and blocks its homodimerization. CPAF activation is initiated by trans-autocatalytic cleavage, which induces homodimerization and conformational changes that assemble the catalytic triad. This assembly leads to two autocatalytic cleavages and removal of the inhibitory segment, enabling full CPAF activity. CPAF is covalently bound and inhibited by the proteasome inhibitor lactacystin. These results reveal the activation mechanism of the CPAF serine protease and suggest new opportunities for anti-Chlamydia drug development.

Chlamydia trachomatis Infection and Photosensitive Dermatoses

BACKGROUND

Photosensitivity to Chlamydia trachomatis has been described in almost 50% of chronic cases of lymphogranuloma venereum (LGV) caused by L1, L2 or L3 serovars. Photosensitivity in non LGV strains of C trachomatis has not been studied. We studied the association of various photosensitive dermatoses with C trachomatis infection in non LGV cases.

METHODS

Sera of all the cases of photosensitivity, melasma, chronic actinic dermatitis (CAD), polymorphic light eruption (PLE), actinic prurigo (AP) and rosacea were tested for the presence of IgM, IgG and IgA antibodies to C trachomatis by ELISA method. The results were compared with 30 healthy controls.

RESULT

Seventeen (25.53%) of 57 cases of photosensitivity as against two (6.67%) controls were seropositive for IgM/IgG/IgA antibodies, a statistically significant difference (χ(2) 6.18, p 0.013). Similarly, significantly higher seropositivity was observed in 12 (25.53%) of 47 cases of melasma (χ(2) 4.38, p 0.0363) and six (46.15%) of 13 cases with CAD (χ(2) 6.91, p 0.0086). Although higher proportion of patients of rosacea [five (31.25%) of 16 cases] and PLE [four (25.0%) of 16 cases] were seropositive, the difference was not statistically significant (χ(2) 3.23, p >0.05, OR 6.36, CI 95% 0 to 48 and χ(2) 3.09, p 0.078, OR 4.67, CI 95% 5 to 41 respectively). There was no association of AP.

CONCLUSION

The observations suggest that C trachomatis infection in non LGV cases is an important cause of PS, melasma and CAD. It appears to be an important cause of rosacea and PLE. We recommend that all cases of photosensitivity, melasma, CAD, PMLE and rosacea and their spouses/sexual contacts be investigated for C trachomatis infection.

The proinflammatory cytokine response to Chlamydia trachomatis elementary bodies in human macrophages is partly mediated by a lipoprotein, the macrophage infectivity potentiator, through TLR2/TLR1/TLR6 and CD14

Chlamydiae components and signaling pathway(s) responsible for the production of proinflammatory cytokines by human monocytes/macrophages are not clearly identified. To this aim, Chlamydia trachomatis-inactivated elementary bodies (EB) as well as the following seven individual Ags were tested for their ability to induce the production of proinflammatory cytokines by human monocytes/macrophages and THP-1 cells: purified LPS, recombinant heat shock protein (rhsp)70, rhsp60, rhsp10, recombinant polypeptide encoded by open reading frame 3 of the plasmid (rpgp3), recombinant macrophage infectivity potentiator (rMip), and recombinant outer membrane protein 2 (rOmp2). Aside from EB, rMip displayed the highest ability to induce release of IL-1beta, TNF-alpha, IL-6, and IL-8. rMip proinflammatory activity could not be attributed to Escherichia coli LPS contamination as determined by the Limulus Amoebocyte lysate assay, insensitivity to polymyxin B (50 microg/ml), and different serum requirement. We have recently demonstrated that Mip is a "classical" bacterial lipoprotein, exposed at the surface of EB. The proinflammatory activity of EB was significantly attenuated in the presence of polyclonal Ab to rMip. Native Mip was able to induce TNF-alpha and IL-8 secretion, whereas a nonlipidated C20A rMip variant was not. Proinflammatory activity of rMip was unaffected by heat or proteinase K treatments but was greatly reduced by treatment with lipases, supporting a role of lipid modification in this process. Stimulating pathways appeared to involve TLR2/TLR1/TLR6 with the help of CD14 but not TLR4. These data support a role of Mip lipoprotein in pathogenesis of C. trachomatis-induced inflammatory responses.

Long-term effects of natural amino acids on infection with Chlamydia trachomatis

Supplementation of culture media with leucine, isoleucine, methionine, or phenylalanine was previously found to inhibit Chlamydia trachomatis growth in HEp-2 cells. Here, we investigated the long-term effects of these additives on C. trachomatis infection in the same cell model. Amino acid addition 30h post-infection (pi) effectively suppressed the generation of infectious progeny monitored for 10 days pi. With the exception of phenylalanine, amino acid treatment beginning at 2h pi for up to 15 days led to a complete lack of infectious progeny. Phenylalanine treatment resulted in residual minimal infectivity. In extended supplementation experiments, very small aberrant chlamydial inclusions formed, whose numbers decreased considerably over time, and the production of infectious chlamydiae could not be rescued even upon amino acid withdrawal. Interestingly, a state of chlamydial persistence was induced under these conditions, as 16S rRNA transcripts were detected throughout treatment. However, expression of several key chlamydial genes including omp1, groEL, omcB, and those functioning for chlamydial DNA replication and cytokinesis was generally very low or even undetected, particularly in monolayers treated with Leu, Ile, or Met. These data revealed a capacity of certain amino acids to eliminate infectious chlamydial progeny. Additionally, supplementation of certain amino acids resulted in the formation of a small persistent population. Extrapolating from these findings may help formulate an anti-chlamydial treatment based on nutritional elements.

Outcome of urogenital infection with Chlamydia muridarum in CD14 gene knockout mice

BACKGROUND

CD14 has been postulated to play a role in chlamydial immunity and immunopathology. There is evidence to support this role in human infections but its function in a mouse model has not been investigated.

METHODS

Female CD14 gene knockout and C57BL/6J wild type mice were infected intravaginally with Chlamydia muridarum. The infection course was monitored by detection of viable chlamydiae from serially collected cervical-vaginal swabs. The sequela of tubal factor infertility was assessed using hydrosalpinx formation as a surrogate marker.

RESULTS

A significantly abbreviated infection course was observed in the CD14 gene knockout mice but hydrosalpinx formation occurred at similar rates between the two groups.

CONCLUSION

Involvement of CD14 during chlamydial infection impedes infection resolution but this does not affect the sequela of infertility as assessed by hydrosalpinx formation.

The secreted protease factor CPAF is responsible for degrading pro-apoptotic BH3-only proteins in Chlamydia trachomatis-infected cells

Chlamydia trachomatis has evolved a profound anti-apoptotic activity that may aid in chlamydial evasion of host defense. The C. trachomatis anti-apoptotic activity has been correlated with blockade of mitochondrial cytochrome c release, inhibition of Bax and Bak activation, and degradation of BH3-only proteins. This study presents evidence that a chlamydia-secreted protease factor designated CPAF is both necessary and sufficient for degrading the BH3-only proteins. When the C. trachomatis-infected cell cytosolic extracts were fractionated by column chromatography, both the CPAF protein and activity elution peaks overlapped with the BH3-only protein degradation activity peak. Depletion of CPAF with a CPAF-specific antibody removed the BH3-only protein degradation activity from the infected cell cytosolic extracts, whereas depletion with control antibodies failed to do so. Notably, recombinant CPAF expressed in bacteria was able to degrade the BH3-only proteins, whereas CPAF mutants similarly prepared from bacteria failed to do so. Finally, bacterium-expressed CPAF also degraded the human BH3-only protein Pumaalpha purified from bacteria. These results demonstrate that CPAF contributes to the chlamydial anti-apoptotic activity by degrading the pro-apoptotic BH3-only Bcl-2 subfamily members.

Profiling of human antibody responses to Chlamydia trachomatis urogenital tract infection using microplates arrayed with 156 chlamydial fusion proteins

The available chlamydial genome sequences have made it possible to comprehensively analyze host responses to all chlamydial proteins, which is essential for further understanding of chlamydial pathogenesis and development of effective chlamydial vaccines. Microplates arrayed with 156 Chlamydia trachomatis fusion proteins were used to evaluate antibody responses in women urogenitally infected with C. trachomatis. Based on both the antibody recognition frequency and titer, seven chlamydial antigens encoded by open reading frames (ORFs) CT089, CT147, CT226, CT681, CT694, CT795, and CT858, respectively, were identified as relatively immunodominant; six of these are encoded by hypothetical ORFs. Antibody binding to these chlamydial fusion proteins was blocked by C. trachomatis-infected but not by normal HeLa cell lysates or irrelevant bacterial lysates. These results have revealed novel immune-reactive chlamydial antigens, not only indicating that the hypothetical ORF-encoded proteins are expressed during chlamydial infection in humans but also providing the proof of principle that the fusion protein-based approach can be used to profile human immune responses to chlamydial infection at the whole-genome scale.

Evaluation of a recombinant enzyme-linked immunosorbent assay for detecting Chlamydophila psittaci antibodies in turkey sera

Chlamydophila psittaci (formerly Chlamydia psittaci) is one of the major pathogens associated with turkey respiratory disease. Devastating outbreaks with high mortality rates, similar to those of 1950 to 1970 in the USA occasionally occur, but respiratory signs without or with low mortality mostly characterize outbreaks now a day. Accurate diagnostic methods should be made available. The present study examined the sensitivity and specificity of a recombinant ELISA (rMOMP ELISA) for detecting Cp. psittaci major outer membrane specific antibodies in turkey sera. Test results were compared to those of immunoblotting and of a competitive ELISA (Chlamydia-psittaci-AK-EIA, Röhm Pharma, Germany) and an indirect ELISA (LPS/LGP) detecting antibodies to the lipopolysaccharide/lipoglycoprotein complex. The rMOMP ELISA was most sensitive as determined on serial dilutions of positive control sera originating from experimentally infected SPF turkeys. The competitive ELISA gave false positives since three negative controls reacted positive. For conventional sera, the sensitivities of the competitive ELISA, immunoblotting and the indirect ELISA were found to be 99.4, 93.1 and 82.2%, respectively, as compared to the rMOMP ELISA (100%). The specificities of the rMOMP ELISA, immunoblotting and the indirect ELISA were found to be 100% while the specificity of the competitive ELISA was only 2.7%. The rMOMP ELISA was chosen to compare the prevalence of chlamydiosis in 2002 with the one from 1992. In 2002, 188 on 200 (94%) turkey sera reacted positive compared to 175 on 200 (87.5%) in 1992 and like 10 years ago all examined farms were seropositive at slaughter. Interestingly, Belgian as well as French farms were seropositive.

Ultrastructural analysis of chlamydial antigen-containing vesicles everting from the Chlamydia trachomatis inclusion

Several chlamydial antigens have been detected in the infected epithelial cell cytosol and on the host cell surface prior to their presumed natural release at the end of the 72-96 h developmental cycle. These extra-inclusion antigens are proposed to influence vital host cell functions, antigen trafficking and presentation and, ultimately, contribute to a prolonged inflammatory response. To begin to dissect the mechanisms for escape of these antigens from the chlamydial inclusion, which are enhanced on exposure to antibiotics, polarized endometrial epithelial cells (HEC-1B) were infected with Chlamydia trachomatis serovar E for 36 h or 48 h. Infected cells were then exposed to chemotactic human polymorphonuclear neutrophils not loaded or pre-loaded in vitro with the antibiotic azithromycin. Viewed by electron microscopy, the azithromycin-mediated killing of chlamydiae involved an increase in chlamydial outer membrane blebbing followed by the appearance of the blebs in larger vesicles (i) everting from but still associated with the inclusion as well as (ii) external to the inclusion. Evidence that the vesicles originated from the chlamydial inclusion membrane was shown by immuno-localization of inclusion membrane proteins A, F, and G on the vesicular membranes. Chlamydial heat shock protein 60 (chsp60) copies 2 and 3, but not copy 1, were released from RB and incorporated into the everted inclusion membrane vesicles and delivered to the infected cell surface. These data represent direct evidence for one mechanism of early antigen delivery, albeit membrane-bound, beyond the confines of the chlamydial inclusion.

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.

Vaccination with the Chlamydia trachomatis major outer membrane protein can elicit an immune response as protective as that resulting from inoculation with live bacteria

BALB/c mice were vaccinated by the intramuscular (i.m.) and subcutaneous (s.c.) routes with a native preparation of the Chlamydia trachomatis mouse pneumonitis (MoPn) major outer membrane protein (MOMP), using Montanide ISA 720 and CpG-1826 as adjuvants. A negative control group was immunized with ovalbumin and the two adjuvants, and a positive control group was immunized intranasally (i.n.) with 10(4) inclusion-forming units (IFU) of C. trachomatis. Four weeks after the last i.m.-plus-s.c. immunization, mice were challenged in the ovarian bursa with 10(5) IFU of C. trachomatis MoPn. Six weeks after the genital challenge, animals were mated, and the pregnancies were monitored. After vaccination with MOMP, the mice developed strong Chlamydia-specific humoral and cellular immune responses. Following the genital challenge, of the mice vaccinated with the MOMP, only 15% (3/20) had positive vaginal cultures, while 85% (17/20) of the animals immunized with ovalbumin had positive cultures over the 6 weeks of observation (P < 0.05). Also, only 14% (3/21) of the animals inoculated i.n. with Chlamydia had positive vaginal cultures. After mating, 75% (15/20) of the mice vaccinated with MOMP carried embryos in both uterine horns. Of the animals vaccinated i.n. with the Chlamydia, 81% (17/21) had embryos in both uterine horns (P > 0.05). In contrast, only 10% (2/20) of the mice immunized with ovalbumin had embryos in both uterine horns (P < 0.05). In conclusion, immunization with a purified preparation of the MOMP is as effective as vaccination with viable C. trachomatis in eliciting a protective immune response against a genital challenge in mice.

Heat shock proteins in autoimmune diseases

Heat shock proteins (hsp's) are among the most conserved proteins in evolution. They have been identified as important pathogen-related antigens as well as autoantigens suitable for construction of novel vaccines. The high evolutionary homology of hsp's has raised the question about the safety of such vaccines. Experimental and clinical observations have confirmed that hsp proteins are involved in the regulation of some autoimmune disease such as autoimmune arthritis, type 1 diabetes mellitus, atherosclerosis, multiple sclerosis, and other autoimmune reactions. It has been shown in experimental animals that some hsp proteins (especially hsp60, hsp70, and hsp10) can either induce or prevent autoimmune reactions depending on the circumstances. This article discusses the involvement of hsp proteins in the etiology of autoimmune diseases and it presents promising experimental data on the effects of immunization with hsp proteins in the prevention and therapy of autoimmune diseases.

Chlamydial GroEL autoregulates its own expression through direct interactions with the HrcA repressor protein

In the pathogenic bacterium Chlamydia trachomatis, a transcriptional repressor, HrcA, regulates the major heat shock operons, dnaK and groE. Cellular stress causes a transient increase in transcription of these heat shock operons through relief of HrcA-mediated repression, but the pathway leading to derepression is unclear. Elevated temperature alone is not sufficient, and it is hypothesized that additional chlamydial factors play a role. We used DNA affinity chromatography to purify proteins that interact with HrcA in vivo and identified a higher-order complex consisting of HrcA, GroEL, and GroES. This endogenous HrcA complex migrated differently than recombinant HrcA, but the complex could be disrupted, releasing native HrcA that resembled recombinant HrcA. In in vitro assays, GroEL increased the ability of HrcA to bind to the CIRCE operator and to repress transcription. Other chlamydial heat shock proteins, including the two additional GroEL paralogs present in all chlamydial species, did not modulate HrcA activity.

Risk of trachomatous scarring and trichiasis in Gambians varies with SNP haplotypes at the interferon-gamma and interleukin-10 loci

Experimental evidence implicates interferon gamma (IFNgamma) in protection from and resolution of chlamydial infection. Conversely, interleukin 10 (IL10) is associated with susceptibility and persistence of infection and pathology. We studied genetic variation within the IL10 and IFNgamma loci in relation to the risk of developing severe complications of human ocular Chlamydia trachomatis infection. A total of 651 Gambian subjects with scarring trachoma, of whom 307 also had potentially blinding trichiasis and pair-matched controls with normal eyelids, were screened for associations between single-nucleotide polymorphisms (SNPs), SNP haplotypes and the risk of disease. MassEXTEND (Sequenom) and MALDI-TOF mass spectrometry were used for detection and analysis of SNPs and the programs PHASE and SNPHAP used to infer haplotypes from population genetic data. Multivariate conditional logistic regression analysis identified IL10 and IFNgamma SNP haplotypes associated with increased risk of both trachomatous scarring and trichiasis. SNPs in putative IFNgamma and IL10 regulatory regions lay within the disease-associated haplotypes. The IFNgamma +874A allele, previously linked to lower IFNgamma production, lies in the IFNgamma risk haplotype and was more common among cases than controls, but not significantly so. The promoter IL10-1082G allele, previously associated with high IL10 expression, is in both susceptibility and resistance haplotypes.

Infection du tractus génital masculin : le point de vue du bactériologiste

Male genital tract infection and inflammation have been associated to 8 to 35% of male infertility cases in various studies. Their investigation is part of a multi-disciplinary process including new techniques as DNA integrity study. Bacterial seminal infection can cause transient or chronic persistent inflammation, and the microbiological investigations, as well as leukospermia, secretory chlamydial IgA and inflammatory cytokines help to approach the responsibility of inflammation in infertility or pathological condition, leading to antibiotic and anti-inflammatory treatment. In Assisted Reproductive Techniques (ART), bacteriospermia must be eradicated for a safe semen preparation to inseminate or to fertilize oocytes. Leukocytes cannot be completely eliminated by sperm preparation and the presence of antibiotics and antioxydants in the culture media is questionned.

Heat shock protein 60 autoimmunity and early lipid lesions in cholesterol-fed C57BL/6JBom mice during Chlamydia pneumoniae infection

Chronic Chlamydia pneumoniae infection and autoimmunity to heat shock protein 60 (Hsp60) have both been documented to be associated with atherosclerosis. Herein, we studied the effects of C. pneumoniae infection and a diet with a low-cholesterol supplement on the development of autoantibodies to mouse Hsp60 and early lipid lesions in the aortic valve of C57BL/6JBom mice. In addition, pulmonary infection was investigated. C57BL/6JBom mice were given one to three C. pneumoniae inoculations and fed either a regular diet or a diet enriched with 0.2% cholesterol. Autoantibody responses against mouse Hsp60 developed in both diet groups when the mice were infected with C. pneumoniae and in uninfected mice fed a cholesterol-enriched diet. C. pneumoniae infections increased subendothelial foam cell accumulation in mice on a 0.2% cholesterol-enriched diet (p = 0.022), without apparent hypercholesterolemia. These in vivo data suggest that autoantibodies against mouse Hsp60 develop as a consequence of cholesterol feeding and repeated C. pneumoniae infections. Further, infectious burden increased early lipid lesions in C57BL/6JBom mice fed a cholesterol-enriched diet.

DNA vaccines expressing antigens with a stress protein-capturing domain display enhanced immunogenicity

An expression system for DNA vaccines is described, in which a fusion protein with an N-terminal, viral J-domain that captures heat-shock proteins (Hsps) is translated in-frame with C-terminal antigen-encoding sequences (of various lengths and origins). The system supports enhanced expression of chimeric antigens (of >800 residues in length) with an extended half life (>8 h). When used as a DNA vaccine, it delivers antigen together with the intrinsic adjuvant activity provided by bound Hsps. We describe the design of vectors for DNA vaccination that support the expression of different immunogenic domains of different origins as large, Hsp-capturing chimeric fusion antigens. The immunogenicity of the antigens produced by this expression system (when it is built into DNA vaccines) has been characterized in detail, with particular emphasis on priming CD8+ T-cell responses. We also discuss areas of vaccine research to which the new technology may provide useful contributions.

Immunoblotting, ELISA and culture evidence for Chlamydiaceae in sows on 258 Belgian farms

The prevalence of Chlamydiaceae infections on 258 closed pig breeding farms in Belgium was examined. For this purpose, 258 farms were randomly selected in the provinces West-Vlaanderen (44%), Oost-Vlaanderen (20%), Antwerpen (10%) and Vlaams-Brabant (6%). Of all farms examined, 96.5% were positive for Chlamydia-specific antibodies in ELISA and most were moderately to strongly positive. ELISA results revealed only 9 (3.5%) sero-negative farms. None of the ELISA negative sera reacted in immunoblotting. Only 212 of 249 ELISA positive sera reacted positive in immunoblotting. Additionally, 23 autopsy samples were examined by isolation in Vero cells. The major outer membrane sequence of the one isolate obtained showed 98.6% amino acid homology to the one of Chlamydophila psittaci strain CP3, formerly isolated from a pigeon. Present observations indicate that chlamydial infections are nearly endemic in the Belgian pig population and that Belgian pigs can become infected with C. psittaci. Nevertheless, the role and significance of Chlamydiaceae as pathogens in pigs remain unsolved and require further investigation.

Chlamydophila abortus pelvic inflammatory disease

We report the first documented case of an extragestational infection with Chlamydophila abortus in humans. The pathogen was identified in a patient with severe pelvic inflammatory disease (PID) by sequence analysis of the ompA gene. Our findings raise the possibility that Chlamydiaceae other than Chlamydia trachomatis are involved in PID.

Follicular fluid antibodies to Chlamydia trachomatis and human heat shock protein-60 kDa and infertility in women

BACKGROUND

The objective of this study was to establish the relationship between presence of anti-Chlamydia trachomatis and anti-HSP60 antibodies in serum and follicular fluid of infertile women.

METHODS

Serum IgG and follicular fluid IgA to Chlamydia trachomatis and human heat shock protein 60 (HSP60) were determined in 41 women undergoing in vitro fertilization (IVF).

RESULTS

A significant association was found between presence of bacterial antibodies in serum and IgA anti-HSP60 in follicular fluid.

CONCLUSIONS

Chlamydia trachomatis infection might be triggering an autoimmune process that could negatively affect the success of IVF.