Chlamydia trachomatis infection: incidence, health costs and prospects for vaccine development

Phenotypic and Genotypic Antimicrobial Susceptibility Testing of Chlamydia trachomatis Isolates from Patients with Persistent or Clinical Treatment Failure in Spain

The aim of this multicentre project (seven hospitals across the Spanish National Health Service) was to study the phenotypic and genotypic susceptibility of C. trachomatis to the main antimicrobials used (macrolides, doxycycline, and quinolones) in isolates from patients with clinical treatment failure in whom reinfection had been ruled out. During 2018-2019, 73 clinical isolates were selected. Sixty-nine clinical specimens were inoculated onto confluent McCoy cell monolayers for phenotypic susceptibility testing. The minimum inhibitory concentration for azithromycin and doxycycline was defined as the lowest concentration associated with an at least 95% reduction in inclusion-forming units after one passage in the presence of the antibiotic compared to the initial inoculum for each strain (control). Sequencing analysis was performed for the genotypic detection of resistance to macrolides, analysing mutations in the 23S rRNA gene (at positions 2057, 2058, 2059, and 2611), and quinolones, analysing a fragment of the gyrA gene, and searching for the G248T mutation (Ser83->Ile). For tetracyclines, in-house RT-PCR was used to test for the tet(C) gene. The phenotypic susceptibility testing was successful for 10 isolates. All the isolates had minimum inhibitory concentrations for azithromycin ≤ 0.125 mg/L and for doxycycline ≤ 0.064 mg/L and were considered sensitive. Of the 73 strains studied, no mutations were found at positions T2611C or G248T of the gyrA gene. We successfully sequenced 66 isolates. No macrolide resistance-associated mutations were found at positions 2057, 2058, 2059, or T2611C. None of the isolates carried the tet(C) gene. We found no evidence for genomic resistance in this large, clinically relevant dataset.

Chlamydia trachomatis as a Current Health Problem: Challenges and Opportunities

Chlamydia is one of the most common sexually transmitted bacterial infections (STIs) worldwide. It is caused by Chlamydia trachomatis (CT), which is an obligate intracellular bacterium. In some cases, it can occur in coinfection with other parasites, increasing the pathologic potential of the infection. The treatment is based on antibiotic prescription; notwithstanding, the infection is mostly asymptomatic, which increases the risk of transmission. Therefore, some countries have implemented Chlamydia Screening Programs in order to detect undiagnosed infections. However, in Portugal, there is no CT screening plan within the National Health Service. There is no awareness in the general healthcare about the true magnitude of this issue because most of the methods used are not Nucleic Acid Amplification Technology-based and, therefore, lack sensitivity, resulting in underreporting infection cases. CT infections are also associated with possible long-term severe injuries. In detail, persistent infection triggers an inflammatory milieu and can be related to severe sequels, such as infertility. This infection could also trigger gynecologic tumors in women, evidencing the urgent need for cost-effective screening programs worldwide in order to detect and treat these individuals adequately. In this review, we have focused on the success of an implemented screening program that has been reported in the literature, the efforts made concerning the vaccine discovery, and what is known regarding CT infection. This review supports the need for further fundamental studies in this area in order to eradicate this infection and we also suggest the implementation of a Chlamydia Screening Program in Portugal.

The Role of IL-17 During Infections in the Female Reproductive Tract

Interleukin-17 (IL-17A) is a cytokine involved in a complex array of both protective and detrimental processes. Although early biological studies focused on the pro-inflammatory function of IL-17 in the context of autoimmune and inflammatory disorders, it has become increasingly evident that the roles of IL-17 are far more nuanced. Recent work has demonstrated that the functions of IL-17 are highly context- and tissue-dependent, and there is a fine balance between the pathogenic and protective functions of IL-17. This is especially evident in mucosal tissues such as the female reproductive tract, where IL-17 has been shown to play an important role in the immune response generated during fungal, bacterial and viral infections associated with protection, but also with inflammation. In this review, we discuss the evolving landscape of IL-17 biology within the context of the vaginal mucosa, focusing on key findings that highlight the importance of this cytokine in genital mucosal immunity.

Persistence and Significance of Chlamydia trachomatis in the Housefly, Musca domestica L

Trachoma is the leading cause of infectious blindness worldwide. Ocular infection by the obligate intracellular pathogen, Chlamydia trachomatis, causes the eyelashes to turn in and scratch the cornea, leading to blindness if left untreated. The disease is most prevalent in poor, rural communities that lack the infrastructure for basic hygiene, clean water, and proper sanitation. Infection is often spread through infected clothes, contaminated hands, and face seeking flies. The goal of this research was to understand the biological role of Musca domestica flies in the transmission of C. trachomatis. PCR, tissue culture, and immunofluorescence microscopy were used to determine the presence, viability, and the anatomical location of C. trachomatis within the digestive tract of M. domestica. Flies were fed with C. trachomatis and then harvested at various time intervals after feeding. The data confirmed the presence of C. trachomatis DNA and viable elementary bodies (EBs) in fly crops, up to 24 h postfeeding. C. trachomatis DNA was also isolated from the upper portions of the alimentary tract of flies up to 48 h postfeeding. In addition, DNA was isolated from the regurgitation material from fly crops up to 12 h postfeeding. The viability of isolated C. trachomatis EBs was repeatedly confirmed between 12 and 48 h and up to 7 days in ex vivo crops stored at room temperature. Our data suggest that eye-seeking flies such as M. domestica can ingest C. trachomatis during regular feeding. Because M. sorbens does not occur in continental United States, we did not use it in any of our studies. These data also confirm, for the first time, that ingested chlamydia remains viable inside the flies for 24-48 h postfeeding. We further show that these flies can regurgitate and transmit the trachoma agent at their next feeding. We believe that these findings reveal an opportunity for efficient intervention strategies through fly vector control, especially as we near new target date for global elimination of trachoma.

Differential expression of groEL-1, incB, pyk-F, tal, hctA and omcB genes during Chlamydia trachomatis developmental cycle

Chlamydia trachomatis infects squamous and columnar epithelia at the mucosal surface. Research on gene expression patterns of C. trachomatis has predominantly focused on non-native host cells, with limited data on growth kinetics and gene expression of chlamydia in keratinocytes. Here, we investigated whether early, mid, and late chlamydial genes observed in HeLa cell line studies were co-ordinately regulated at the transcriptional level even in the keratinized cell line model and whether the expression was stage-specific during the developmental cycle. HaCaT cell lines were infected with chlamydia clinical isolates (US151and serovar E) and reference strain (L2 434). Expression of groEL-1, incB, pyk-F, tal, hctA, and omcB genes was conducted with comparative real-time PCR and transcriptional events during the chlamydial developmental cycle using transmission electron microscopy. The relative expression level of each gene and fold difference were calculated using the 2-ΔΔCT method. The expression of groEL-1 and pyk-F genes was highest at 2 hours post-infection (hpi) in the L2 434 and serovar E. The expression of incB gene increased at 2 hpi in L2 434 and serovar E but peaked at 12 hpi in serovar E. L2 434 and US151 had similar tal expression profiles. Increased expression of hctA and omcB genes were found at 2 and 36 hpi in L2 434. Both clinical isolates and reference strains presented the normal chlamydial replication cycle comprising elementary bodies and reticulate bodies within 36 hpi. We show different gene expression patterns between clinical isolates and reference strain during in vitro infection of keratinocytes, with reference strain-inducing consistent expression of genes. These findings confirm that keratinocytes are appropriate cell lines to interrogate cell differentiation, growth kinetics, and gene expression of C. trachomatis infection. Furthermore, more studies with different clinical isolates and genes are needed to better understand the Chlamydial pathogenesis in keratinocytes.

Microbial Evolution: Chlamydial Creatures from the Deep

A metagenomic study of marine sediments from a hydrothermal vent field in the Arctic Mid-Ocean Ridge revealed wider diversity amongst members of the phylum Chlamydiae than was previously known. Unlike known chlamydiae, some of the newly described marine-sediment species may be potentially free-living.

Structure-based drug target prioritisation and rational drug design for targeting Chlamydia trachomatis eye infections

Chlamydia trachomatis (C.t) is a major causative of infectious blindness in world. It is a real challenge to combat Chlamydial infection as it is an intracellular pathogen. Hence, it is essential to determine the most potential targets of C.t in order to inhibit or suppress its virulence during its infectious phase. Thus, in this study, the highly expressed-cum-most essential genes reported through our earlier study were reprioritized by structure-based comparative binding site analysis with host proteome. Therefore, computational approaches involving molecular modelling, large-scale binding site prediction and comparison, molecular dynamics simulation studies were performed to narrow down the most potential targets. Furthermore, high-throughput virtual screening and ADMETox were also performed to identify potential hits that shall efficiently inhibit the prioritised targets. Hence, by this study we report Pyruvoyl-dependent arginine decarboxylase (PvlArgDC), DNA-repair protein (RecO) and porin (outer membrane protein) as the most viable targets of C.t which can be potentially targeted by compounds, NSC_13086, MFCD00276409, MFCD05662003, respectively. AbbreviationsC.tChlamydia trachomatisSTDSexually transmitted diseaseHTVSHigh-throughput virtual screeningADMEToxAbsorption, Distribution, Metabolism, Excretion and ToxicityPMPocketMatchMDMolecular Dynamics simulationSPStandard precisionXPExtra precisionMMGBSAMolecular mechanics energies combined with generalised Born and surface area continuum solvationOMPOuter membrane proteinPvlArgDCPyruvoyl-dependent arginine decarboxylaseRecORecombination protein O.Communicated by Ramaswamy H. Sarma.

Protection against genital tract Chlamydia trachomatis infection following intranasal immunization with a novel recombinant MOMP VS2/4 antigen

The asymptomatic nature of most Chlamydia trachomatis infections and the lack of appropriate effects by current prevention and management call for vaccine development. We evaluated a recombinant subunit vaccine candidate based on the major outer membrane protein variable segments 2 and 4 (MOMP VS2/4). To achieve maximal immunogenicity and ease of production and purification, MOMP VS2/4 was constructed by using highly immunogenic sequences of MOMP only, thereby minimizing the presence of hydrophobic regions, and spacing the immunogenic epitopes with a flexible amino acid sequence. A purification tag was also added. The MOMP VS2/4 was given intranasally, with or without intravaginal boost, with cholera toxin (CT) adjuvant to C57BL/6 mice, which were screened for immunogenicity and protection against a live challenge infection with C. trachomatis serovar D. Bacterial shedding, cell-mediated responses, and antibody responses were monitored. Immunized mice exhibited significantly less bacterial shedding and were better protected against infertility as compared to unimmunized control mice. Immunizations stimulated both systemic and local specific antibody (IgG1, IgG2c, and IgA) responses, and primed T cells that produced interferon-γ and interleukins 13 and 17 upon challenge with recall antigen. Thus, MOMP VS2/4, in combination with CT adjuvant, stimulated Th1, Th2, and Th17 effector cells, and generated protective immunity associated with less pathology. We regard MOMP VS2/4 as a promising candidate for further development into a mucosal chlamydial vaccine.

Exploration of testing practices and population characteristics support an increase in chlamydia positivity in Tasmania between 2001 and 2010

OBJECTIVE

The proportion of positive chlamydia tests in young people in Tasmania increased significantly between 2001 and 2010. While female positivity rates increased steadily, male positivity rose steeply to 2005 then stabilised. Crude positivity rates can be influenced by a variety of factors making interpretation difficult. Unique Tasmanian datasets were used to explore whether symptom status, reason for testing or sexual exposure could explain the observed positivity trends.

METHODS

Population-level chlamydia positivity rates in Tasmania over a 10-year period were compared with surveillance data collected on people aged 15 to 29 years notified with chlamydia.

RESULTS

The proportion of asymptomatic chlamydia cases increased, with the largest increase in males aged 15 to 19 years (28%). Opportunistic testing of cases increased (greatest in males, range 17-32%). Sexual exposure remained consistent.

CONCLUSIONS

After allowing for any changes in sexual exposure, symptom status and reason for testing, an increase in chlamydia positivity occurred over the 10 years. Healthcare providers have increased chlamydia testing in high-risk groups.

IMPLICATIONS

Monitoring chlamydia testing patterns and positivity rates at a population level is a step forward in surveillance practices. Targeted surveys provide valuable information to supplement routine surveillance data.

Use of a Guinea pig-specific transcriptome array for evaluation of protective immunity against genital chlamydial infection following intranasal vaccination in Guinea pigs

Guinea pigs have been used as a second animal model to validate putative anti-chlamydial vaccine candidates tested in mice. However, the lack of guinea pig-specific reagents has limited the utility of this animal model in Chlamydia sp. vaccine studies. Using a novel guinea pig-specific transcriptome array, we determined correlates of protection in guinea pigs vaccinated with Chlamydia caviae (C. caviae) via the intranasal route, previously reported by us and others to provide robust antigen specific immunity against subsequent intravaginal challenge. C. caviae vaccinated guinea pigs resolved genital infection by day 3 post challenge. In contrast, mock vaccinated animals continued to shed viable Chlamydia up to day 18 post challenge. Importantly, at day 80 post challenge, vaccinated guinea pigs experienced significantly reduced genital pathology - a sequelae of genital chlamydial infections, in comparison to mock vaccinated guinea pigs. Sera from vaccinated guinea pigs displayed antigen specific IgG responses and increased IgG1 and IgG2 titers capable of neutralizing GPIC in vitro. Th1-cellular/inflammatory immune genes and Th2-humoral associated genes were also found to be elevated in vaccinated guinea pigs at day 3 post-challenge and correlated with early clearance of the bacterium. Overall, this study provides the first evidence of guinea pig-specific genes involved in anti-chlamydial vaccination and illustrates the enhancement of the utility of this animal model in chlamydial pathogenesis.

STI-GMaS: an open-source environment for simulation of sexually-transmitted infections

Background

Sexually-transmitted pathogens often have severe reproductive health implications if treatment is delayed or absent, especially in females. The complex processes of disease progression, namely replication and ascension of the infection through the genital tract, span both extracellular and intracellular physiological scales, and in females can vary over the distinct phases of the menstrual cycle. The complexity of these processes, coupled with the common impossibility of obtaining comprehensive and sequential clinical data from individual human patients, makes mathematical and computational modelling valuable tools in developing our understanding of the infection, with a view to identifying new interventions. While many within-host models of sexually-transmitted infections (STIs) are available in existing literature, these models are difficult to deploy in clinical/experimental settings since simulations often require complex computational approaches.

Results

We present STI-GMaS (Sexually-Transmitted Infections – Graphical Modelling and Simulation), an environment for simulation of STI models, with a view to stimulating the uptake of these models within the laboratory or clinic. The software currently focuses upon the representative case-study of Chlamydia trachomatis, the most common sexually-transmitted bacterial pathogen of humans. Here, we demonstrate the use of a hybrid PDE–cellular automata model for simulation of a hypothetical Chlamydia vaccination, demonstrating the effect of a vaccine-induced antibody in preventing the infection from ascending to above the cervix. This example illustrates the ease with which existing models can be adapted to describe new studies, and its careful parameterisation within STI-GMaS facilitates future tuning to experimental data as they arise.

Conclusions

STI-GMaS represents the first software designed explicitly for in-silico simulation of STI models by non-theoreticians, thus presenting a novel route to bridging the gap between computational and clinical/experimental disciplines. With the propensity for model reuse and extension, there is much scope within STI-GMaS to allow clinical and experimental studies to inform model inputs and drive future model development. Many of the modelling paradigms and software design principles deployed to date transfer readily to other STIs, both bacterial and viral; forthcoming releases of STI-GMaS will extend the software to incorporate a more diverse range of infections.

Presence of Chlamydiales DNA in ticks and fleas suggests that ticks are carriers of Chlamydiae

The Chlamydiales order includes the Chlamydiaceae, Parachlamydiaceae, Waddliaceae, Simkaniaceae, Criblamydiaceae, Rhabdochlamydiaceae, Clavichlamydiaceae, and Piscichlamydiaceae families. Members of the Chlamydiales order are obligate intracellular bacteria that replicate within eukaryotic cells of different origins including humans, animals, and amoebae. Many of these bacteria are pathogens or emerging pathogens of both humans and animals, but their true diversity is largely underestimated, and their ecology remains to be investigated. Considering their potential threat on human health, it is important to expand our knowledge on the diversity of Chlamydiae, but also to define the host range colonized by these bacteria. Thus, using a new pan-Chlamydiales PCR, we analyzed the prevalence of Chlamydiales DNA in ticks and fleas, which are important vectors of several viral and bacterial infectious diseases. To conduct this study, 1340 Ixodes ricinus ticks prepared in 192 pools were collected in Switzerland and 55 other ticks belonging to different tick species and 97 fleas belonging to different flea species were harvested in Algeria. In Switzerland, the prevalence of Chlamydiales DNA in the 192 pools was equal to 28.1% (54/192) which represents an estimated prevalence in the 1340 individual ticks of between 4.0% and 28.4%. The pan-Chlamydiales qPCR was positive for 45% (25/55) of tick samples collected in Algeria. The sequencing of the positive qPCR amplicons revealed a high diversity of Chlamydiales species. Most of them belonged to the Rhabdochlamydiaceae and Parachlamydiaceae families. Thus, ticks may carry Chlamydiales and should thus be considered as possible vectors for Chlamydiales propagation to both humans and animals.

Usefulness of 11C-choline positron emission tomography for genital chlamydial infection assessment in a BALB/c murine model

PURPOSE

The aim of this study is to explore the feasibility of 11C-Choline PET in the assessment of the degree of inflammation in the Chlamydia muridarum genital infection model.

PROCEDURES

Forty female Balb/c mice received 2.5 mg of medroxyprogesterone acetate i.m. 9 and 2 days prior to the infection: 21 mice were infected by C. muridarum into the vaginal vault, 12 mice were treated with inactivated chlamydiae, and 7 mice were SPG buffer-treated as negative controls. Three healthy control mice were not treated with progesterone. Mice in each category were randomly subdivided in two groups: (1) sacrificed at 5, 10, 15, and 20 days for histological analysis and (2) undergoing 11C-Choline PET at days 5, 10, and 20 post-infection (20 MBq of 11C-Choline, uptake time of 10 min, acquisition through a small-animal PET tomograph for 15 min).

RESULTS

Infected animals showed a significantly higher standardized uptake value than both controls and animals inoculated with heat-inactivated chlamydiae in each PET scan (P<0.05). All organs of the infected animals had scores of inflammation ranging between 2 and 3 at day 5, decreasing to 1-2 at day 20.

CONCLUSIONS

This preliminary result demonstrated that 11C-Choline PET can highlight a specific proliferation mechanism of inflammatory cells induced by C. muridarum, thanks to a very high sensitivity in detecting very small amounts of tracer in inflammatory cells.

The duration of Chlamydia muridarum genital tract infection and associated chronic pathological changes are reduced in IL-17 knockout mice but protection is not increased further by immunization

IL-17 is believed to be important for protection against extracellular pathogens, where clearance is dependent on neutrophil recruitment and local activation of epithelial cell defences. However, the role of IL-17 in protection against intracellular pathogens such as Chlamydia is less clear. We have compared (i) the course of natural genital tract C. muridarum infection, (ii) the development of oviduct pathology and (iii) the development of vaccine-induced immunity against infection in wild type (WT) BALB/c and IL-17 knockout mice (IL-17-/-) to determine if IL-17-mediated immunity is implicated in the development of infection-induced pathology and/or protection. Both the magnitude and duration of genital infection was significantly reduced in IL-17-/- mice compared to BALB/c. Similarly, hydrosalpinx was also greatly reduced in IL-17-/- mice and this correlated with reduced neutrophil and macrophage infiltration of oviduct tissues. Matrix metalloproteinase (MMP) 9 and MMP2 were increased in WT oviducts compared to IL-17-/- animals at day 7 post-infection. In contrast, oviducts from IL-17-/- mice contained higher MMP9 and MMP2 at day 21. Infection also elicited higher levels of Chlamydia-neutralizing antibody in serum of IL-17-/- mice than WT mice. Following intranasal immunization with C. muridarumMajor Outer Membrane Protein (MOMP) and cholera toxin plus CpG adjuvants, significantly higher levels of chlamydial MOMP-specific IgG and IgA were found in serum and vaginal washes of IL-17-/- mice. T cell proliferation and IFNγ production by splenocytes was greater in WT animals following in vitro re-stimulation, however vaccination was only effective at reducing infection in WT, not IL-17-/- mice. Intranasal or transcutaneous immunization protected WT but not IL-17-/- mice against hydrosalpinx development. Our data show that in the absence of IL-17, the severity of C. muridarum genital infection and associated oviduct pathology are significantly attenuated, however neither infection or pathology can be reduced further by vaccination protocols that effectively protect WT mice.

Novel HLA-B27-restricted epitopes from Chlamydia trachomatis generated upon endogenous processing of bacterial proteins suggest a role of molecular mimicry in reactive arthritis

Reactive arthritis (ReA) is an HLA-B27-associated spondyloarthropathy that is triggered by diverse bacteria, including Chlamydia trachomatis, a frequent intracellular parasite. HLA-B27-restricted T-cell responses are elicited against this bacterium in ReA patients, but their pathogenetic significance, autoimmune potential, and relevant epitopes are unknown. High resolution and sensitivity mass spectrometry was used to identify HLA-B27 ligands endogenously processed and presented by HLA-B27 from three chlamydial proteins for which T-cell epitopes were predicted. Fusion protein constructs of ClpC, Na(+)-translocating NADH-quinone reductase subunit A, and DNA primase were expressed in HLA-B27(+) cells, and their HLA-B27-bound peptidomes were searched for endogenous bacterial ligands. A non-predicted peptide, distinct from the predicted T-cell epitope, was identified from ClpC. A peptide recognized by T-cells in vitro, NQRA(330-338), was detected from the reductase subunit. This is the second HLA-B27-restricted T-cell epitope from C. trachomatis with relevance in ReA demonstrated to be processed and presented in live cells. A novel peptide from the DNA primase, DNAP(211-223), was also found. This was a larger variant of a known epitope and was highly homologous to a self-derived natural ligand of HLA-B27. All three bacterial peptides showed high homology with human sequences containing the binding motif of HLA-B27. Molecular dynamics simulations further showed a striking conformational similarity between DNAP(211-223) and its homologous and much more flexible human-derived HLA-B27 ligand. The results suggest that molecular mimicry between HLA-B27-restricted bacterial and self-derived epitopes is frequent and may play a role in ReA.

Formulation, characterization, and expression of a recombinant MOMP Chlamydia trachomatis DNA vaccine encapsulated in chitosan nanoparticles

Chlamydia trachomatis is a bacterial sexually transmitted infection affecting millions of people worldwide. Previous vaccination attempts have employed the recombinant major outer membrane protein (MOMP) of C. trachomatis nonetheless, with limited success, perhaps, due to stability, degradation, and delivery issues. In this study we cloned C. trachomatis recombinant MOMP DNA (DMOMP) and encapsulated it in chitosan nanoparticles (DMCNP) using the complex coacervation technique. Physiochemical characterizations of DMCNP included transmission and scanning electron microcopy, Fourier transform infrared and ultraviolet-visible spectroscopy, and zeta potential. Encapsulated DMOMP was 167–250 nm, with a uniform spherical shape and homogenous morphology, and an encapsulation efficiency > 90%. A slow release pattern of encapsulated DMOMP, especially in acidic solution, was observed over 7 days. The zeta potential of DMCNP was ~8.80 mV, which indicated that it was highly stable. Toxicity studies of DMCNP (25–400 μg/mL) to Cos-7 cells using the MTT assay revealed minimal toxicity over 24–72 hours with >90% viable cells. Ultra-violet visible (UV-vis) spectra indicated encapsulated DMOMP protection by chitosan, whereas agarose gel electrophoresis verified its protection from enzymatic degradation. Expression of MOMP protein in DMCNP-transfected Cos-7 cells was demonstrated via Western blotting and immunofluorescence microscopy. Significantly, intramuscular injection of BALB/c mice with DMCNP confirmed the delivery of encapsulated DMOMP, and expression of the MOMP gene transcript in thigh muscles and spleens. Our data show that encapsulation of DMOMP in biodegradable chitosan nanoparticles imparts stability and protection from enzymatic digestion, and enhances delivery and expression of DMOMP in vitro and in mice. Further investigations of the nanoencapsulated DMCNP vaccine formulation against C. trachomatis in mice are warranted.

Rab11-family of interacting protein 2 associates with chlamydial inclusions through its Rab-binding domain and promotes bacterial multiplication

Chlamydia trachomatis, an obligate intracellular pathogen, survives within host cells in a special compartment named 'inclusion' and takes advantage of host vesicular transport pathways for its growth and replication. Rab GTPases are key regulatory proteins of intracellular trafficking. Several Rabs, among them Rab11 and Rab14, are implicated in chlamydial development. FIP2, a member of the Rab11-Family of Interacting Proteins, presents at the C-terminus a Rab-binding domain that interacts with both Rab11 and Rab14. In this study, we determined and characterized the recruitment of endogenous and GFP-tagged FIP2 to the chlamydial inclusions. The recruitment of FIP2 is specific since other members of the Rab11-Family of Interacting Proteins do not associate with the chlamydial inclusions. The Rab-binding domain of FIP2 is essential for its association. Our results indicate that FIP2 binds to Rab11 at the chlamydial inclusion membrane through its Rab-binding domain. The presence of FIP2 at the chlamydial inclusion favours the recruitment of Rab14. Furthermore, our results show that FIP2 promotes inclusion development and bacterial replication. In agreement, the silencing of FIP2 decreases the bacterial progeny. C. trachomatis likely recruits FIP2 to hijack host intracellular trafficking to redirect vesicles full of nutrients towards the inclusion.

Biodegradable PLGA85/15 nanoparticles as a delivery vehicle for Chlamydia trachomatis recombinant MOMP-187 peptide

Development of a Chlamydia trachomatis vaccine has been a formidable task partly because of an ineffective delivery system. Our laboratory has generated a recombinant peptide of C. trachomatis major outer membrane protein (MOMP) (rMOMP-187) and demonstrated that it induced at 20 μg ml(-1) maximal interleukin (IL)-6 and IL-12p40 Th1 cytokines in mouse J774 macrophages. In a continuous pursuit of a C. trachomatis effective vaccine-delivery system, we encapsulated rMOMP-187 in poly(d,l-lactic-co-glycolic acid) (PLGA, 85:15 PLA/PGA ratio) to serve as a nanovaccine candidate. Physiochemical characterizations were assessed by Fourier transform-infrared spectroscopy, atomic force microscopy, Zetasizer, Zeta potential, transmission electron microcopy and differential scanning calorimetry. The encapsulated rMOMP-187 was small (∼200 nm) with an apparently smooth uniform oval structure, thermally stable (54 °C), negatively charged ( - 27.00 mV) and exhibited minimal toxicity at concentrations <250 μg ml (-1) to eukaryotic cells (>95% viable cells) over a 24-72 h period. We achieved a high encapsulation efficiency of rMOMP-187 (∼98%) in PLGA, a loading peptide capacity of 2.7% and a slow release of the encapsulated peptide. Stimulation of J774 macrophages with a concentration as low as 1 μg ml (-1) of encapsulated rMOMP-187 evoked high production levels of the Th1 cytokines IL-6 (874 pg ml(-1)) and IL-12p40 (674 pg ml(-1)) as well as nitric oxide (8 μM) at 24 h post-stimulation, and in a dose-response and time-kinetics manner. Our data indicate the successful encapsulation and characterization of rMOMP-187 in PLGA and, more importantly, that PLGA enhanced the capacity of the peptide to induce Th1 cytokines and NO in vitro. These findings make this nanovaccine an attractive candidate in pursuit of an efficacious vaccine against C. trachomatis.

Vaccination to protect against infection of the female reproductive tract

Infection of the female genital tract can result in serious morbidities and mortalities from reproductive disability, pelvic inflammatory disease and cancer, to impacts on the fetus, such as infant blindness. While therapeutic agents are available, frequent testing and treatment is required to prevent the occurrence of the severe disease sequelae. Hence, sexually transmitted infections remain a major public health burden with ongoing social and economic barriers to prevention and treatment. Unfortunately, while there are two success stories in the development of vaccines to protect against HPV infection of the female reproductive tract, many serious infectious agents impacting on the female reproductive tract still have no vaccines available. Vaccination to prevent infection of the female reproductive tract is an inherently difficult target, with many impacting factors, such as appropriate vaccination strategies/mechanisms to induce a suitable protective response locally in the genital tract, variation in the local immune responses due to the hormonal cycle, selection of vaccine antigen(s) that confers effective protection against multiple variants of a single pathogen (e.g., the different serovars of Chlamydia trachomatis) and timing of the vaccine administration prior to infection exposure. Despite these difficulties, there are numerous ongoing efforts to develop effective vaccines against these infectious agents and it is likely that this important human health field will see further major developments in the next 5 years.

A comparison of the effects of a chlamydial vaccine administered during or after a C. muridarum urogenital infection of female mice

Research into an efficacious Chlamydia trachomatis vaccine is ongoing, however, there has been no examination into the timing of vaccine administration to either asymptomatically or previously infected individuals. Using the female Chlamydia muridarum genital tract mouse model, we examined this aspect of vaccine development. Our results show timing of vaccination affected the production of systemic antibodies, but had minimal effects on mucosal antibody production. Vaccination during an active infection or after a resolved infection did not provide protection against re-exposure to Chlamydia, and did not exacerbate the development of pathological sequelae in infected mice. This demonstrates that vaccination may not be protective in individuals who are seropositive for an acute or previous chlamydial infection.

Modulation of the Chlamydia trachomatis in vitro transcriptome response by the sex hormones estradiol and progesterone

Background

Chlamydia trachomatis is a major cause of sexually transmitted disease in humans. Previous studies in both humans and animal models of chlamydial genital tract infection have suggested that the hormonal status of the genital tract epithelium at the time of exposure can influence the outcome of the chlamydial infection. We performed a whole genome transcriptional profiling study of C. trachomatis infection in ECC-1 cells under progesterone or estradiol treatment.

Results

Both hormone treatments caused a significant shift in the sub-set of genes expressed (25% of the transcriptome altered by more than 2-fold). Overall, estradiol treatment resulted in the down-regulation of 151 genes, including those associated with lipid and nucleotide metabolism. Of particular interest was the up-regulation in estradiol-supplemented cultures of six genes (omcB, trpB, cydA, cydB, pyk and yggV), which suggest a stress response similar to that reported previously in other models of chlamydial persistence. We also observed morphological changes consistent with a persistence response. By comparison, progesterone supplementation resulted in a general up-regulation of an energy utilising response.

Conclusion

Our data shows for the first time, that the treatment of chlamydial host cells with key reproductive hormones such as progesterone and estradiol, results in significantly altered chlamydial gene expression profiles. It is likely that these chlamydial expression patterns are survival responses, evolved by the pathogen to enable it to overcome the host's innate immune response. The induction of chlamydial persistence is probably a key component of this survival response.

Immune regulation of a chronic bacteria infection and consequences for pathogen transmission

Background

The role of host immunity has been recognized as not only playing a fundamental role in the interaction between the host and pathogen but also in influencing host infectiousness and the ability to shed pathogens. Despite the interest in this area of study, and the development of theoretical work on the immuno-epidemiology of infections, little is known about the immunological processes that influence pathogen shedding patterns.

Results

We used the respiratory bacterium Bordetella bronchiseptica and its common natural host, the rabbit, to examine the intensity and duration of oro-nasal bacteria shedding in relation to changes in the level of serum antibodies, blood cells, cytokine expression and number of bacteria colonies in the respiratory tract. Findings show that infected rabbits shed B. bronchiseptica by contact up to 4.5 months post infection. Shedding was positively affected by number of bacteria in the nasal cavity (CFU/g) but negatively influenced by serum IgG, which also contributed to the initial reduction of bacteria in the nasal cavity. Three main patterns of shedding were identified: i- bacteria were shed intermittently (46% of individuals), ii- bacteria shedding fell with the progression of the infection (31%) and iii- individuals never shed bacteria despite being infected (23%). Differences in the initial number of bacteria shed between the first two groups were associated with differences in the level of serum antibodies and white blood cells. These results suggest that the immunological conditions at the early stage of the infection may play a role in modulating the long term dynamics of B. bronchiseptica shedding.

Conclusions

We propose that IgG influences the threshold of bacteria in the oro-nasal cavity which then affects the intensity and duration of individual shedding. In addition, we suggest that a threshold level of infection is required for shedding, below this value individuals never shed bacteria despite being infected. The mechanisms regulating these interactions are still obscure and more studies are needed to understand the persistence of bacteria in the upper respiratory tract and the processes controlling the intensity and duration of shedding.

Chlamydia trachomatis, a hidden epidemic: effects on female reproduction and options for treatment

The number of genital tract Chlamydia trachomatis infections is steadily increasing worldwide, with approximately 50-70% of infections asymptomatic. There is currently no uniform screening practice, current antibiotic treatment has failed to prevent the increased incidence, and there is no vaccine available. We examined studies on the epidemiology of C. trachomatis infections, the effects infections have on the female reproductive tract and subsequent reproductive health and what measures are being taken to reduce these problems. Undetected or multiple infections in women can lead to the development of severe reproductive sequelae, including pelvic inflammatory disease and tubal infertility. There are two possible paradigms of chlamydial pathogenesis, the cellular and immunological paradigms. While many vaccine candidates are being extensively tested in animal models, they are still years from clinical trials. With no vaccine available and antibiotic treatment unable to halt the increased incidence, infection rates will continue to increase and cause a significant burden on health care systems.

Oral immunization with a novel lipid-based adjuvant protects against genital Chlamydia infection

Oral immunization is attractive as a delivery route because it is needle-free and useful for rapid mass vaccination programs to target pandemics or bioterrorism. This potential has not been realized for human vaccination, due to the requirement of large antigen doses and toxic (to humans) adjuvants to overcome the induction of oral tolerance and potential degradation of antigens in the stomach. To date, only oral vaccines based on live attenuated organisms have been approved for human use. In this study we describe the use of a lipid-based delivery system/adjuvant, Lipid C, for oral immunization to protect mice against genital tract chlamydial infection. Lipid C is formulated from food-grade purified and fractionated triglycerides. Bacterial shedding following vaginal challenge with Chlamydia muridarum was reduced by 50% in female mice orally immunized with the chlamydial major outer membrane protein (MOMP) formulated in Lipid C, protection equivalent to that seen in animals immunized with MOMP admixed with both cholera toxin (CT) and CpG oligodeoxynucleotides (CpG-ODN). Protection was further enhanced when MOMP, CT and CpG were all combined in the Lipid C matrix. Protection correlated with production of gamma interferon (IFN) by splenic T cells, a serum MOMP-specific IgG response and low but detectable levels of MOMP-specific IgA in vaginal lavage.

Chlamydia trachomatis evokes a relative anti-inflammatory response in a free Ca2+ dependent manner in human macrophages

Chlamydia trachomatis infections manifest as unique, chronic inflammatory diseases, indicating a relative compromise in the capacity of early immune responders such as macrophages to resolve the infection. We decided to investigate whether or not the chronic inflammatory manifestations are influenced by a disturbance in the pattern of inflammatory:anti-inflammatory cytokine elaboration early in the infection cycle in macrophages and assess the possible modulatory role of Ca(2+) signals in the process. Although the basal and functional levels of IL-12 and IL-10 are not identical in concentration, chlamydia initiated a significant decline in IL-12. This led to a difference in the ratio of time-course decline in IL-12 compared with IL-10 in a Ca(2+)-poor medium, while there was significant increase in IL-10 in a Ca(2+)-rich medium. Also, when macrophages were infected after treatment with drugs that either facilitated Ca(2+) influx into cells or inhibited efflux from intracellular stores into cytosol, there was a significant enhancement of the elaboration of IL-10 compared with IL-12. The immobilization of cytosolic Ca(2+) by BAPTA-AM resulted in the decline of macrophage IL-12 and IL-10 in both infected and uninfected cases. There was evidence that infectivity and status of chlamydial elementary bodies harvested from macrophages during these experiments were consistent with chronic forms as assessed by HSP-60:MOMP ratio. The implication of these findings is that chlamydia infection of macrophages, together with its capacity to moderate macrophage intracellular Ca(2+) levels, may evoke a net anti-inflammatory response that presumably favors chronic chlamydia infections.

Chlamydia trachomatis infection modulates trophoblast cytokine/chemokine production

It is well established that intrauterine infections can pose a threat to pregnancy by gaining access to the placenta and fetus, and clinical studies have strongly linked bacterial infections with preterm labor. Although Chlamydia trachomatis (Ct) can infect the placenta and decidua, little is known about its effects on trophoblast cell immune function. We have demonstrated that Ct infects trophoblast cells to form inclusions and completes the life cycle within these cells by generating infectious elementary bodies. Moreover, infection with Ct leads to differential modulation of the trophoblast cell's production of cytokines and chemokines. Using two human first trimester trophoblast cell lines, Sw.71 and H8, the most striking feature we found was that Ct infection results in a strong induction of IL-1beta secretion and a concomitant reduction in MCP-1 (CCL2) production in both cell lines. In addition, we have found that Ct infection of the trophoblast results in the cleavage and degradation of NF-kappaB p65. These findings suggest that the effect of a Chlamydia infection on trophoblast secretion of chemokines and cytokines involves both activation of innate immune receptors expressed by the trophoblast and virulence factors secreted into the trophoblast by the bacteria. Such altered trophoblast innate immune responses may have a profound impact on the microenvironment of the maternal-fetal interface and this could influence pregnancy outcome.

Host immune responses to chlamydial inclusion membrane proteins B and C in Chlamydia trachomatis infected women with or without fertility disorders

BACKGROUND

With an increase in the number of putative inclusion membrane proteins (incs) in chlamydial genomes, there is a need for understanding their contribution in host-pathogen interactions. Thus in this study we determined the host mucosal and peripheral immune responses to incs (IncB and IncC) of Chlamydia trachomatis (CT).

METHODS

Female patients (n = 296) attending the gynaecology out patient department of Safdarjung hospital, New Delhi were enrolled for the study and were clinically characterized into two groups; CT-positive fertile women (n = 38) and CT-positive women with fertility disorders (n = 29). Uninfected healthy fertile women were enrolled as controls (n = 31). Gene specific PCRs were used for detection of incB and incC genes in endocervical samples of CT-positive patients. ELISA and Western blot assay were used for detection of IgA and IgG antibodies to IncB and IncC in cervical washes and sera. Effect of IncB and IncC stimulation of cervical cells and PBMCs on cellular proliferation and cytotoxity was determined using MTT assay and Lactate dehydrogenase (LDH)-cytotoxicity assay respectively. Modulation of cytokines (Interleukin (IL)-1 Beta, IL-4, IL-5, IL-6, IL-10, Interferon-gamma, IL-12, Tumor Necrosis Factor-alpha and Granulocyte macrophage colony-stimulating factor (GM-CSF)) in cervical cells and PBMCs upon stimulation with IncB and IncC was determined by real-time reverse-transcriptase (RT)-PCR and ELISA. Further, CD4 positive T cells were purified from cervical cells and peripheral blood mononuclear cells (PBMCs) and secreted cytokines (Interferon-gamma and IL-4) were evaluated by ELISPOT and real-time RT-PCR.

RESULTS

Using MTT assay, significantly high proliferative responses (P < 0.05) were observed in inc-stimulated cervical cells and PBMCs from CT-positive fertile women compared to CT-positive women with fertility disorders and controls. Interferon-gamma, IL-12 and GM-CSF were found to be elevated in inc-stimulated cervical cells and PBMCs of CT-positive fertile women compared to CT-positive women with fertility disorders and controls (P < 0.05). In contrast, IL-1 Beta, IL-4, IL-5, IL-6 and IL-10 levels were found to be higher in CT-positive women with fertility disorders compared to CT-positive fertile women and controls (P < 0.05). Interferon-gamma secreting cells and mRNA expression in inc-stimulated cervical and peripheral CD4 positive T cells were significantly higher (P < 0.05) in CT positive fertile women compared to CT-positive women with fertility disorders.

CONCLUSION

Our data overall suggests that CT incs, IncB and IncC modulate host immune responses and may have a role in protection/pathogenesis of genital chlamydial infection in women.

Blockade of epithelial membrane protein 2 (EMP2) abrogates infection of Chlamydia muridarum murine genital infection model

New methods are needed to eradicate or prevent Chlamydia trachomatis infections. Blockade of epithelial membrane protein 2 (EMP2) by genetic silencing or neutralizing polyclonal antibody reduced chlamydial infectivity in vitro. This study tests the prediction that recombinant anti-EMP2 diabody could reduce early chlamydial infection of the genital tract in vivo. In a murine infection model, pretreatment with anti-EMP2 diabody, as compared with control diabody, significantly reduced bacterial load, tissue production of inflammatory cytokines, recruitment of polymorphonuclear leukocytes, and local tissue inflammation. These findings support EMP2 as a potential preventative and therapeutic target for genital chlamydial infection.

Innate immunity and disorders of the female reproductive tract

Sexually transmitted infections, and their associated sequelae, such as tubal infertility, ectopic pregnancy and preterm labour, are a major worldwide health problem. Chlamydia trachomatis infection is thought to be the leading global cause of tubal infertility and tubal ectopic pregnancy. Preterm birth occurs in around 10% of all deliveries, and nearly 30% of preterm deliveries are associated with intrauterine infection. The mucosal innate immune system of the female reproductive tract has evolved to eliminate such sexually transmitted pathogens whilst maintaining its ability to accommodate specialized physiological functions that include menstruation, fertilization, implantation, pregnancy and parturition. The aim of this review was to describe the role and distribution of key mediators of the innate immune system, the natural antimicrobial peptides (secretory leukocyte protease inhibitor, elafin and the defensins) and the pattern recognition toll-like receptors in the normal female reproductive tract and in the context of these pathological processes.

A real-time quantitative polymerase chain reaction assay for the detection of Chlamydia in the mouse genital tract model

Chlamydia trachomatis is a human pathogen that infects genital tracts in women. Disease control may be achieved through development of an efficacious vaccine. A mouse genital tract model serves as a tool for evaluation of vaccine candidates. Currently, assessment of infection in mice is performed by enumeration of inclusion-forming units (IFUs) through microscopic counting of fluorescently stained bacteria. We have developed a highly sensitive real-time quantitative polymerase chain reaction (RT-qPCR) assay for enumeration of Chlamydia from mouse genital tracts to increase assay sensitivity, remove subjectivity, and improve sample throughput. The qPCR assay uses a 16S ribosomal gene sequence that is conserved across Chlamydia species and serovars, resulting in detection of multiple serovars of C. trachomatis, as well as Chlamydia muridarum and Chlamydia pneumoniae. The PCR assay provided results similar to IFU enumeration (94% agreement between the 2 assays) and is highly sensitive and specific with less inherent subjectivity than traditional enumeration methods.

Pattern recognition at the maternal-fetal interface

Intrauterine infections represent a significant threat to fetal well-being and pregnancy outcome. Recent studies suggest that non-immune cells of the maternal-fetal interface can actively recognize and respond to microbes through pattern recognition receptors, in order to control pathogens that may compromise the pregnancy. However, these same innate immune responses may inadvertently lead to excessive inflammation or apoptosis at the maternal-fetal interface. Thus, pattern recognition receptors may play a key role in infection-related pregnancy complications. This review discusses what is currently known about the role of Toll-like receptors and NOD-like receptors in controlling infections at the maternal-fetal interface, and what impact their function may have on pregnancy.

Chlamydia muridarum infection subverts dendritic cell function to promote Th2 immunity and airways hyperreactivity

There is strong epidemiological evidence that Chlamydia infection can lead to exacerbation of asthma. However, the mechanism(s) whereby chlamydial infection, which normally elicits a strong Th type 1 (Th1) immune response, can exacerbate asthma, a disease characterized by dominant Th type 2 (Th2) immune responses, remains unclear. In the present study, we show that Chlamydia muridarum infection of murine bone marrow-derived dendritic cells (BMDC) modulates the phenotype, cytokine secretion profile, and Ag-presenting capability of these BMDC. Chlamydia-infected BMDC express lower levels of CD80 and increased CD86 compared with noninfected BMDC. When infected with Chlamydia, BMDC secrete increased TNF-alpha, IL-6, IL-10, IL-12, and IL-13. OVA peptide-pulsed infected BMDC induced significant proliferation of transgenic CD4(+) DO11.10 (D10) T cells, strongly inhibited IFN-gamma secretion by D10 cells, and promoted a Th2 phenotype. Intratracheal transfer of infected, but not control noninfected, OVA peptide-pulsed BMDC to naive BALB/c mice, which had been i.v. infused with naive D10 T cells, resulted in increased levels of IL-10 and IL-13 in bronchoalveolar lavage fluid. Recipients of these infected BMDC showed significant increases in airways resistance and decreased airways compliance compared with mice that had received noninfected BMDC, indicative of the development of airways hyperreactivity. Collectively, these data suggest that Chlamydia infection of DCs allows the pathogen to deviate the induced immune response from a protective Th1 to a nonprotective Th2 response that could permit ongoing chronic infection. In the setting of allergic airways inflammation, this infection may then contribute to exacerbation of the asthmatic phenotype.

Disc derangements of the temporomandibular joint

Disc-related derangement of the temporomandibular joint is common and epidemiological research has found that about 20% of the population may be affected. Although very few of these people have the more prominent symptoms, recent data indicate that the numbers who need treatment is increasing. The two clinical variants of disc derangement, reciprocal clicking and closed lock, have long been recognized, but the association between them and their aetiology and pathogenesis is still unclear. As a consequence, there is still uncertainty on how to treat the conditions, and this is even more evident when surgery is involved. This paper describes new tissue research related to disc derangement. A simplified scheme is presented and implications for surgical treatment are discussed.

NOD protein expression and function in first trimester trophoblast cells

PROBLEM

Through the expression of pattern recognition receptors, the trophoblast can recognize and respond to infectious microorganisms and, therefore, participate in the control of pathogens that may compromise fetal well-being. We hypothesize that the trophoblast has the ability to sense invasive intracellular bacteria through the cytoplasmic-based nucleotide-binding oligomerization domain (NOD) proteins. The aim of this study was to characterize the expression and function of NOD proteins in first trimester trophoblast cells.

METHOD OF STUDY

NOD1 and NOD2 expressions by first trimester trophoblast cells were evaluated by immunohistochemistry, Western blot analysis and reverse transcription-polymerase chain reaction. The effect of NOD2 activation on trophoblast cells was determined by analyzing the cytokine response following treatment with muramyl dipeptide (MDP).

RESULTS

Both NOD1 and NOD2 were expressed by first trimester placental villi and localized to trophoblast cells. Moreover, NOD1, NOD2 and the signaling effector protein, RIP-like interacting CLARP kinase (RICK), were all expressed by isolated trophoblast cells. Following exposure to the NOD2 ligand, MDP, trophoblast cells generated a pro-inflammatory cytokine response. This response was confirmed to be specific, as an NOD2-deficient trophoblast cell line failed to respond to MDP unless transfected with NOD2.

CONCLUSION

These findings suggest that, through the expression and function of NOD proteins, first trimester trophoblast cells are able to recognize and respond to invasive intracellular pathogens that may have evaded other forms of pattern recognition.

Staining of Chlamydia trachomatis elementary bodies: A suitable method for identifying infected human monocytes by flow cytometry

Persistence of Chlamydia trachomatis (C. trachomatis) in the joint is the most frequent cause of reactive arthritis following urogenital tract infection. The resulting changes of host cell antigen- and cytokine-expression are not precisely understood. We developed and evaluated a direct cytometric approach to visualize in vitro C. trachomatis-infected monocytes. Infectious elementary bodies (EBs) of C. trachomatis serovar K were labelled by incubation with 5-(and-6)-carboxyfluorescein diacetate succinimidyl ester (CFSE). Afterwards, human peripheral blood monocytes were cultured with the CFSE-labelled EBs and analysed by flow cytometry. Real-time polymerase chain reaction (PCR) was used to demonstrate intracellular uptake and viability of CFSE-labelled C. trachomatis by the determination of gene expression. Labelling EBs with CFSE may become a valuable tool for studying the interaction between C. trachomatis and the host cell.

Successful removal of Chlamydia pneumoniae from plateletpheresis products collected using automated leukoreduction hemapheresis techniques

Chlamydia pneumoniae (Cp) is an obligate intracellular pathogen associated with a variety of maladies. Best known for its involvement in community-acquired pneumonia outbreaks; the potential role of Cp in diverse illnesses is a topic of increasing interest and investigation. Previous studies suggested that white blood cells from normal blood donors harboring this agent may be eliminated through leukoreduction by filtration. Here we examine the ability and efficacy of apheresis-related leukoreduction for its effect on the carriage and potential infectivity of these organisms in the preparation of platelet products. Matched pre-apheresis peripheral blood (PB) samples and product samples obtained from healthy plateletpheresis donors were analyzed for the presence and potential infectivity of Cp organisms by direct smear inspection and tissue culture techniques. Antibody seroreactivity directed towards the organism was assessed using a solid phase immunoassay. Forty-eight percent of the donor blood samples exhibited elevated anti-Cp antibody titers (> or =200). Specimens from 31 (27%) and 34 (30%) of 115 plateletpheresis donors were positive for the presence of Cp organisms in their pre-apheresis PB samples when analyzed by direct smear examination and culture, respectively. Examination of the 115 post-leukodepleted plateletpheresis product samples revealed only two (1.7%) and one (0.009%) product(s) to be smear-positive and culture-positive, respectively. Certain plateletpheresis donors may harbor infectious Cp organisms in circulating WBC. Collections from such donors of apheresis platelet products using standard apheresis leukoreduction strategies appear successful in markedly decreasing or eliminating the organisms found in the final products.

Transcutaneous vaccination with virus-like particles

Virus-like particles (VLP) are inert, empty capsids of viruses, which contain no DNA/RNA from the virus itself. However they retain the structure of a virus and they can be engineered to have antigens attached. We have constructed VLP, derived from Rabbit hemorrhagic disease virus, and shown they are highly immunogenic. We tested the capacity of these engineered VLP to induce immune responses when they are administered to mice via the transcutaneous route. This route of vaccination is important, in order to generate mucosal protection. Our data showed that VLP are taken up by dendritic cells (DC), antigen-presenting cells that are essential to initiate acquired immune responses. The VLP induced an increase in expression of CD40, CD80 and CD86 but required an adjuvant, CpG DNA oligo-deoxy nucleotides (ODN) motifs, to enhance these responses. In vivo testing has also shown that the VLP, when wiped on to the skin in conjunction with immunostimulatory CpG, induce Ag-specific immune responses, typified by high levels of IFN-gamma and IgG1.

Localization of TLR2 and MyD88 to Chlamydia trachomatis inclusions. Evidence for signaling by intracellular TLR2 during infection with an obligate intracellular pathogen

Chlamydia trachomatis is an obligate intracellular gram-negative pathogen and the etiologic agent of significant ocular and genital tract diseases. Chlamydiae primarily infect epithelial cells, and the inflammatory response of these cells to the infection directs both the innate and adaptive immune response. This study focused on determining the cellular immune receptors involved in the early events following infection with the L2 serovar of C. trachomatis. We found that dominant negative MyD88 inhibited interleukin-8 (IL-8) secretion during a productive infection with chlamydia. Furthermore, expression of Toll-like receptor (TLR)-2 was required for IL-8 secretion from infected cells, whereas the effect of TLR4/MD-2 expression was minimal. Cell activation was dependent on infection with live, replicating bacteria, because infection with UV-irradiated bacteria and treatment of infected cells with chloramphenicol, but not ampicillin, abrogated the induction of IL-8 secretion. Finally, we show that both TLR2 and MyD88 co-localize with the intracellular chlamydial inclusion, suggesting that TLR2 is actively engaged in signaling from this intracellular location. These data support the role of TLR2 in the host response to infection with C. trachomatis. Our data further demonstrate that TLR2 and the adaptor MyD88 are specifically recruited to the bacterial or inclusion membrane during a productive infection with chlamydia and provide the first evidence that intracellular TLR2 is responsible for signal transduction during infection with an intracellular bacterium.

Progress in vaccines for sexually transmitted diseases

The development pipeline for vaccines to control sexually transmitted infections holds greater promise than ever before. Preclinical studies are encouraging in the development of chlamydia and gonococcal vaccines, and for the first time, recent clinical trials have shown the feasibility of creating vaccines to control genital herpes and cervical human papillomavirus infections. Behavioral research suggests that these vaccines will likely find acceptance among health care providers and consumers.

Comparison of intranasal and transcutaneous immunization for induction of protective immunity against Chlamydia muridarum respiratory tract infection

Chlamydia pneumoniae causes a range of respiratory infections including bronchitis, pharyngitis and pneumonia. Infection has also been implicated in exacerbation/initiation of asthma and chronic obstructive pulmonary disease (COPD) and may play a role in atherosclerosis and Alzheimer's disease. We have used a mouse model of Chlamydia respiratory infection to determine the effectiveness of intranasal (IN) and transcutaneous immunization (TCI) to prevent Chlamydia lung infection. Female BALB/c mice were immunized with chlamydial major outer membrane protein (MOMP) mixed with cholera toxin and CpG oligodeoxynucleotide adjuvants by either the IN or TCI routes. Serum and bronchoalveolar lavage (BAL) were collected for antibody analysis. Mononuclear cells from lung-draining lymph nodes were stimulated in vitro with MOMP and cytokine mRNA production determined by real time PCR. Animals were challenged with live Chlamydia and weighed daily following challenge. At day 10 (the peak of infection) animals were sacrificed and the numbers of recoverable Chlamydia in lungs determined by real time PCR. MOMP-specific antibody-secreting cells in lung tissues were also determined at day 10 post-infection. Both IN and TCI protected animals against weight loss compared to non-immunized controls with both immunized groups gaining weight by day 10-post challenge while controls had lost 6% of body weight. Both immunization protocols induced MOMP-specific IgG in serum and BAL while only IN immunization induced MOMP-specific IgA in BAL. Both immunization routes resulted in high numbers of MOMP-specific antibody-secreting cells in lung tissues (IN>TCI). Following in vitro re-stimulation of lung-draining lymph node cells with MOMP; IFNgamma mRNA increased 20-fold in cells from IN immunized animals (compared to non-immunized controls) while IFNgamma levels increased 6- to 7-fold in TCI animals. Ten days post challenge non-immunized animals had >7,000 IFU in their lungs, IN immunized animals <50 IFU and TCI immunized animals <1,500 IFU. Thus, both intranasal and transcutaneous immunization protected mice against respiratory challenge with Chlamydia. The best protection was obtained following IN immunization and correlated with IFNgamma production by mononuclear cells in lung-draining LN and MOMP-specific IgA in BAL.

Real-time PCR for pharmacodynamic studies of Chlamydia trachomatis

Pharmacodynamic knowledge about Chlamydia trachomatis exposed to antibiotics is hampered due to methodological limitations. We have developed a quantitative real-time PCR method (qRT-PCR) for determination of viable C. trachomatis. The method measures specific RNA transcripts of omp2 (omcB) as an expression of viable C. trachomatis. Two clinical isolates (one strain derived from a patient with recurrent symptoms despite doxycycline treatment) were cultured in McCoy cells and exposed to doxycycline at concentrations of 0.0078-64 mg/L. MIC values were evaluated microscopically by immunofluorescence (IF) and by qRT-PCR performed on cDNA prepared from the total RNA. The MIC for two C. trachomatis strains were determined to 0.016 and 0.031 mg/L by both qRT-PCR and IF. The qRT-PCR assay enabled MIC determinations without subjective evaluation, which is a problem when visually evaluating inclusions. The presented qRT-PCR is a suitable method for MIC determination of C. trachomatis. It has the advantage of giving quantitative measurements of chlamydial RNA levels and the method is useful in pharmacodynamic studies of C. trachomatis.

Intranasal immunization with C. muridarum major outer membrane protein (MOMP) and cholera toxin elicits local production of neutralising IgA in the prostate

Successful control of sexually transmitted diseases (STDs) through vaccination will require the development of vaccine strategies that target protective immunity to both the female and male reproductive tracts (MRT). In the male, the immune privileged nature of the male reproductive tract provides a barrier to entry of serum immunoglobulins into the male reproductive ducts, thereby preventing the induction of protective immunity using conventional injectable vaccination techniques. In this study we investigated the potential of intranasal (IN) immunization to elicit anti-chlamydial immunity in BALB/c male mice. Intranasal immunization with Chlamydia muridarum major outer membrane protein (MOMP) admixed with cholera toxin (CT) resulted in high levels of MOMP-specific IgA in prostatic fluids (PF) and MOMP-specific IgA-secreting cells in the prostate. Prostatic fluid IgA inhibited in vitro infection of McCoy cells with C. muridarum. Using RT-PCR we also show that mRNA for the polymeric immunoglobulin receptor (PIgR), which transports IgA across mucosal epithelia, is expressed only in the prostate but not in other regions of the male reproductive ducts upstream of the prostate. These data suggest that using intranasal immunization to target IgA to the prostate may protect males against STDs while at the same time maintaining the state of immune privilege within the MRT.