Chlamydia inhibit host cell apoptosis by inducing Bag-1 via the MAPK/ERK survival pathway

Chlamydia are obligate intracellular bacteria that frequently cause human disease. Host cells infected with Chlamydia are profoundly resistant to diverse apoptotic stimuli. The inhibition of apoptosis is thought to be an important immune escape mechanism allowing Chlamydia to productively complete their obligate intracellular growth cycle. Chlamydial antiapoptotic activity involves activation of the MAPK/ERK survival pathway. However, the molecular mechanisms are not well understood. Here we show that Bag-1 is up-regulated in Chlamydia-infected cells. U0126 and GW5074 suppress the induction of Bag-1 by Chlamydia, implying that Chlamydia may up-regulate Bag-1 via the MAPK/ERK survival pathway. Overexpression of Bag-1 is sufficient to protect against apoptosis, while depletion of Bag-1 suppresses the antiapoptotic effect of Chlamydia. The data indicate Chlamydia may up-regulate Bag-1 through the MAPK/ERK survival pathway to suppress apoptosis.     

Assessment of the role in protection and pathogenesis of the Chlamydia muridarum V-type ATP synthase subunit A (AtpA) (TC0582)

A novel Chlamydia muridarum antigen (TC0582) was used to vaccinate BALB/c mice. Mice were also immunized with other components of the ATP synthase complex (TC0580, TC0581, and TC0584), or with the major outer membrane protein (MOMP). TC0582 was also formulated in combination with TC0580, TC0581 or MOMP. TC0582 alone, or in combination with the other antigens, elicited strong Chlamydia-specific humoral and cellular immune responses. Vaccinated animals were challenged intranasally and the course of the infection was followed for 10 days. Based on percentage change in body weight, lung weight, and number of Chlamydia inclusion forming units recovered from the lungs, mice immunized with TC0582, TC0581 or MOMP, as single antigens, showed significant protection. Mice immunized with combinations of two antigens were also protected but the level of protection was not additive. TC0582 has sequence homology with the eukaryotic ATP synthase subunit A (AtpA). Therefore, to determine if immunization with TC0582, or with Chlamydia, elicited antibodies that cross-reacted with the mouse AtpA, the two proteins were printed on a microarray. Sera from mice immunized with TC0582 and/or live Chlamydia, strongly reacted with TC0582 but did not recognize the mouse AtpA. In conclusion, TC0582 may be considered as a Chlamydia vaccine candidate.     

Effects of glucocorticoids on the respiratory burst of Chlamydia-primed THP-1 cells

We previously observed that the respiratory burst of human monocytes (THP-1 cell line) triggered by phorbol myristate acetate was strongly enhanced by a priming of the cells by Chlamydia pneumoniae [Biochem. Biophys. Res. Commun. 287 (2001) 781]. We describe here the modifications of the responses of Chlamydia-primed THP-1 cells to hydrocortisone (HCT) and methylprednisolone (MPL). HCT and MPL inhibited the production of the cytokines TNFα and IL-8. But HCT, which inhibited the respiratory burst in LPS-primed monocytes, paradoxically stimulated the phenomenon in Chlamydia-primed cells; MPL exerted no significant effect. Both glucocorticoids did not significantly modify the triggering effect of Chlamydia on NF-κB binding activity. On the expression of p22^phox, a protein subunit of the NADPH oxidase, HCT had an increasing and MPL a decreasing effect. Glucocorticoids thus had unexpected effects on the inflammatory response of Chlamydia-primed monocytes.     

Correlates of attendance at community engagement meetings held in advance of bio-behavioral research studies: A longitudinal,sociocentric social network study in rural Uganda

BackgroundCommunity engagement is central to the conduct of health-related research studies as a way to determine priorities, inform study design and implementation, increase recruitment and retention, build relationships, and ensure that research meets the goals of the community. Community sensitization meetings, a form of community engagement, are often held prior to the initiation of research studies to provide information about upcoming study activities and resolve concerns in consultation with potential participants. This study estimated demographic, health, economic, and social network correlates of attendance at community sensitization meetings held in advance of a whole-population, combined behavioral, and biomedical research study in rural Uganda.Methods and findingsResearch assistants collected survey data from 1,630 adults participating in an ongoing sociocentric social network cohort study conducted in a rural region of southwestern Uganda. These community survey data, collected between 2016 and 2018, were linked to attendance logs from community sensitization meetings held in 2018 and 2019 before the subsequent community survey and community health fair. Of all participants, 264 (16%) attended a community sensitization meeting before the community survey, 464 (28%) attended a meeting before the community health fair, 558 (34%) attended a meeting before either study activity (survey or health fair), and 170 (10%) attended a meeting before both study activities (survey and health fair). Using multivariable Poisson regression models, we estimated correlates of attendance at community sensitization meetings. Attendance was more likely among study participants who were women (adjusted relative risk [ARR]_{health fair} = 1.71, 95% confidence interval [CI], 1.32 to 2.21, p < 0.001), older age (ARR_survey = 1.02 per year, 95% CI, 1.01 to 1.02, p < 0.001; ARR_{health fair} = 1.02 per year, 95% CI, 1.01 to 1.02, p < 0.001), married (ARR_survey = 1.74, 95% CI, 1.29 to 2.35, p < 0.001; ARR_{health fair} = 1.41, 95% CI, 1.13 to 1.76, p = 0.002), and members of more community groups (ARR_survey = 1.26 per group, 95% CI, 1.10 to 1.44, p = 0.001; ARR_{health fair} = 1.26 per group, 95% CI, 1.12 to 1.43, p < 0.001). Attendance was less likely among study participants who lived farther from meeting locations (ARR_survey = 0.54 per kilometer, 95% CI, 0.30 to 0.97, p = 0.041; ARR_{health fair} = 0.57 per kilometer, 95% CI, 0.38 to 0.86, p = 0.007). Leveraging the cohort’s sociocentric design, social network analyses suggested that information conveyed during community sensitization meetings could reach a broader group of potential study participants through attendees’ social network and household connections. Study limitations include lack of detailed data on reasons for attendance/nonattendance at community sensitization meetings; achieving a representative sample of community members was not an explicit aim of the study; and generalizability may not extend beyond this study setting.ConclusionsIn this longitudinal, sociocentric social network study conducted in rural Uganda, we observed that older age, female sex, being married, membership in more community groups, and geographical proximity to meeting locations were correlated with attendance at community sensitization meetings held in advance of bio-behavioral research activities. Information conveyed during meetings could have reached a broader portion of the population through attendees’ social network and household connections. To ensure broader input and potentially increase participation in health-related research studies, the dissemination of research-related information through community sensitization meetings may need to target members of underrepresented groups.

In a social network cohort study, Emily Satinsky and colleagues estimate demographic, health, economic and social network factor associated with attendance at community sensitization meetings held in advance of participation in health-related research studies in rural Uganda.     

Uptake of Biotin by Chlamydia Spp. through the Use of a Bacterial Transporter (BioY) and a Host-Cell Transporter (SMVT)

Chlamydia spp. are obligate intracellular Gram-negative bacterial pathogens that cause disease in humans and animals. Minor variations in metabolic capacity between species have been causally linked to host and tissue tropisms. Analysis of the highly conserved genomes of Chlamydia spp. reveals divergence in the metabolism of the essential vitamin biotin with genes for either synthesis (bioF_2ADB) and/or transport (bioY). Streptavidin blotting confirmed the presence of a single biotinylated protein in Chlamydia. As a first step in unraveling the need for divergent biotin acquisition strategies, we examined BioY (CTL0613) from C. trachomatis 434/Bu which is annotated as an S component of the type II energy coupling-factor transporters (ECF). Type II ECFs are typically composed of a transport specific component (S) and a chromosomally unlinked energy module (AT). Intriguingly, Chlamydia lack recognizable AT modules. Using ³H-biotin and recombinant E. coli expressing CTL0613, we demonstrated that biotin was transported with high affinity (a property of Type II ECFs previously shown to require an AT module) and capacity (apparent K(m) of 3.35 nM and V(max) of 55.1 pmol×min⁻¹×mg⁻¹). Since Chlamydia reside in a host derived membrane vacuole, termed an inclusion, we also sought a mechanism for transport of biotin from the cell cytoplasm into the inclusion vacuole. Immunofluorescence microscopy revealed that the mammalian sodium multivitamin transporter (SMVT), which transports lipoic acid, biotin, and pantothenic acid into cells, localizes to the inclusion. Since Chlamydia also are auxotrophic for lipoic and pantothenic acids, SMVT may be subverted by Chlamydia to move multiple essential compounds into the inclusion where BioY and another transporter(s) would be present to facilitate transport into the bacterium. Collectively, our data validates the first BioY from a pathogenic organism and describes a two-step mechanism by which Chlamydia transport biotin from the host cell into the bacterial cytoplasm.     

The prevalence and identity of Chlamydia-specific IgE in children with asthma and other chronic respiratory symptoms

Background

Recent studies have confirmed the presence of viable Chlamydia in the bronchoalveolar lavage (BAL) fluid of pediatric patients with airway hyperresponsiveness. While specific IgG and IgM responses to C. pneumoniae are well described, the response and potential contribution of Ag-specific IgE are not known. The current study sought to determine if infection with Chlamydia triggers the production of pathogen-specific IgE in children with chronic respiratory diseases which might contribute to inflammation and pathology.

Methods

We obtained BAL fluid and serum from pediatric respiratory disease patients who were generally unresponsive to corticosteroid treatment as well as sera from age-matched control patients who saw their doctor for wellness checkups. Chlamydia-specific IgE was isolated from BAL and serum samples and their specificity determined by Western blot techniques. The presence of Chlamydia was confirmed by species-specific PCR and BAL culture assays.

Results

Chlamydial DNA was detected in the BAL fluid of 134/197 (68%) patients. Total IgE increased with age until 15 years old and then decreased. Chlamydia-specific IgE was detected in the serum and/or BAL of 107/197 (54%) patients suffering from chronic respiratory disease, but in none of the 35 healthy control sera (p < 0.0001). Of the 74 BAL culture-positive patients, 68 (91.9%, p = 0.0001) tested positive for Chlamydia-specific IgE. Asthmatic patients had significantly higher IgE levels compared to non-asthmatics (p = 0.0001). Patients who were positive for Chlamydia DNA or culture had significantly higher levels of serum IgE compared to negative patients (p = 0.0071 and p = 0.0001 respectively). Only 6 chlamydial antigens induced Chlamydia-specific IgE and patients with C. pneumoniae-specific IgE had significantly greater levels of total IgE compared to C. pneumoniae-specific IgE negative ones (p = 0.0001).

Conclusions

IgE antibodies play a central role in allergic inflammation; therefore production of Chlamydia-specific IgE may prove significant in the exacerbation of chronic, allergic airway diseases, thus highlighting a direct role for Chlamydia in asthma pathogenesis.     

Evidence of Infectious Asthma Phenotype: Chlamydia-Induced Allergy and Pathogen-Specific IgE in a Neonatal Mouse Model

Asthma is a chronic respiratory disease whose etiology is poorly understood. Recent studies suggest that early-life respiratory infections with atypical bacteria may play an important role in the induction or exacerbation of chronic respiratory disease. The current study utilized a neonatal mouse ovalbumin (OVA) sensitization model of asthma to determine the course of early-life respiratory tract infection by Chlamydia. Neonatal (day 1) and adult (6 wks) BALB/c mice were infected intranasally with Chlamydia (MoPn) and 7 weeks later were sensitized and challenged with ovalbumin. Allergic airway disease was characterized by examination of serum and bronchoalveolar lavage fluid (BAL) cellularity, cytokine production and antibody response. The presence of Chlamydia was determined by PCR and culture. Ova-specific IgE was quantified by ELISA and Chlamydia-specific IgE was determined via Western blot analysis. Chlamydial infection in neonatal mice induced increased production of Th₂ cytokines (IL-4, 5, 10, and 13) in both BAL and serum, while infected adult mice produced increased Th₁ cytokines (IL-2, IFN-γ). The BAL from infected neonates contained significantly elevated levels of eosinophils compared to infected adult mice. Although adult mice cleared the infection ∼30 days post infection (pi), neonates were still infected 66 days after initial infection. Chlamydia-specific IgE was detected in both the BAL and serum of neonatal mice beginning 28 days post infection, however, infected adult mice did not produce Chlamydia-specific IgE antibodies over the course of the study. When allergic airway was induced using Ova, infected neonatal mice increased their production of IL-4, IL-5 and IL-13 by >2 fold compared to uninfected controls and infected adult groups. Our findings demonstrate that early-life Chlamydia infection induces a Th₂-dominant cytokine response in the airways of neonatal mice, leading to chronic infection. More significantly, early life respiratory colonization with Chlamydia elicits pathogen-specific IgE production, which further supports an infectious asthma phenotype.     

Intracellular Survival and Persistence of Chlamydia muridarum Is Determined by Macrophage Polarization

Macrophages can display a number of distinct phenotypes, known collectively as polarized macrophages. The best defined of these phenotypes are the classically-activated, interferon gamma (IFNγ)/LPS induced (M1) and alternatively-activated, IL-4 induced (M2) macrophages. The goal of this study is to characterize macrophage- Chlamydia interactions in the context of macrophage polarization. Here we use Chlamydia muridarum and murine bone-marrow derived macrophages to show Chlamydia does not induce M2 polarization in macrophages as a survival strategy. Unexpectedly, the infection of macrophages was silent with no upregulation of M1 macrophage-associated genes. We further demonstrate that macrophages polarized prior to infection have a differential capacity to control Chlamydia . M1 macrophages harbor up to 40-fold lower inclusion forming units (IFU) than non-polarized or M2 polarized macrophages. Gene expression analysis showed an increase in 16sRNA in M2 macrophages with no change in M1 macrophages. Suppressed Chlamydia growth in M1 macrophages correlated with the induction of a bacterial gene expression profile typical of persistence as evident by increased Euo expression and decreased Omp1 and Tal expression. Observations of permissive Chlamydia growth in non-polarized and M2 macrophages and persistence in M1 macrophages were supported through electron microscopy. This work supports the importance of IFNγ in the innate immune response to Chlamydia . However, demonstration that the M1 macrophages, despite an antimicrobial signature, fail to eliminate intracellular Chlamydia supports the notion that host–pathogen co-evolution has yielded a pathogen that can evade cellular defenses against this pathogen, and persist for prolonged periods of time in the host.     

生物膜研究在生物物理研究所的兴起与发展

生物膜研究是现代生物学研究的前沿方向之一,本文对文革结束以后生物膜研究在中国科学院生物物理研究所(下称生物物理所)的兴起与发展进行了系统回顾.文革结束后,中国科学院领导了解到国外生物膜研究迅速发展的情况,迅即派遣以生物物理所杨福愉为组长,包括生物化学研究所、动物研究所、植物研究所、上海实验生物研究所等六人的代表团前往联邦德国进行考察.考察结束后院领导根据多学科交叉对生物膜研究的重要作用,组织了生物物理所、植物所、中国医学科学院、北京医科大学等单位联合申报国家自然科学基金委员会重大项目"膜脂-膜蛋白的相互作用及其在医学和农业上的应用",并获得立项.与此同时,院领导建议由中国生物物理学会、中国生化学会和中国细胞生物学会共同组织生物膜学术讨论会.首次会议于1979年3月在北京友谊宾馆举行,以后每3年召开1次,从未中断,有力地促进了生物膜研究的交流与发展.2003年举行的第200届香山会议专门组织讨论21世纪生物膜研究在中国的布局,进一步推动了生物膜研究的发展.本文还重点阐述了中国科学院生物物理研究所在生物膜研究方面所取得的代表性成果:a.金属离子通过膜脂-膜蛋白相互作用调控生物膜能量转换、物质运输及信号转导的分子机制;b.提出"克山病是一种心肌线粒体病"的重要观点;c.发现溶酶体内含有为量甚微、一般认为是消化酶的胰凝乳蛋白酶,并阐明了它通过溶酶体膜外泄后参与细胞凋亡的作用机制;d.确定了通过调控线粒体动态变化而干预肿瘤细胞迁移侵袭的新靶标.最后,特别值得一提的是,2004年,常文瑞与植物研究所匡廷云等在《自然》(Nature)发表了《菠菜中主要捕光色素复合体2.72魡分辨率的晶体结构分析》的研究论文,2005年饶子和与徐建兴等在《细胞》(Cell)发表了《猪心线粒体呼吸链复合体Ⅱ的晶体结构》的研究论文,充分标志着我国生物膜研究已在国际上占据一席之地.2004年,徐涛研究员因其在囊泡转运方面的丰厚学术积淀,作为首席科学家组织一批生物膜专家承担了国内首个生物膜973项目,这标志着国内生物膜研究开始进入一个新的发展时期.     

Candidatus Syngnamydia Venezia,a Novel Member of the Phylum Chlamydiae from the Broad Nosed Pipefish,Syngnathus typhle

Chlamydia are obligate intracellular bacteria and important pathogens of humans and animals. Chlamydia-related bacteria are also major fish pathogens, infecting epithelial cells of the gills and skin to cause the disease epitheliocystis. Given the wide distribution, ancient origins and spectacular diversity of bony fishes, this group offers a rich resource for the identification and isolation of novel Chlamydia. The broad-nosed pipefish (Syngnathus typhle) is a widely distributed and genetically diverse temperate fish species, susceptible to epitheliocystis across much of its range. We describe here a new bacterial species, Candidatus Syngnamydia venezia; epitheliocystis agent of S. typhle and close relative to other chlamydial pathogens which are known to infect diverse hosts ranging from invertebrates to humans.     

New point of care Chlamydia Rapid Test—bridging the gap between diagnosis and treatment: performance evaluation study

Objective To evaluate the performance of a new Chlamydia Rapid Test with vaginal swab specimens as a potential tool for chlamydia diagnosis and screening.Design Performance evaluation study.Settings A young people’s sexual health centre (site 1) and two genitourinary medicine clinics (sites 2 and 3) in the United Kingdom.Participants 1349 women aged between 16 and 54 attending one of the three clinics.Main outcome measures Sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test versus polymerase chain reaction and strand displacement amplification assays; correlation between the Chlamydia Rapid Test visual signal and organism load; acceptability to participants of self collected vaginal swabs as the specimen type for Chlamydia testing.Results Polymerase chain reaction positivity rates for Chlamydia trachomatis infection were 8.4% (56/663) at site 1, 9.4% (36/385) at site 2, and 6.0% (18/301) at site 3. Compared with polymerase chain reaction assay, the resolved sensitivity, specificity, positive predictive value, and negative predictive value of the Chlamydia Rapid Test were 83.5% (91/109), 98.9% (1224/1238), 86.7% (91/105), and 98.6% (1224/1242). Compared with strand displacement amplification assay, sensitivity and specificity of the Chlamydia Rapid Test were 81.6% (40/49) and 98.3% (578/588). Organism load of self collected vaginal swabs ranged from 5.97×10² to 1.09×10⁹ Chlamydia plasmids per swab, which correlated well with the Chlamydia Rapid Test’s visual signal (r=0.6435, P<0.0001). Most (95.9%) surveyed participants felt comfortable about collecting their own swabs.Conclusions The performance of the Chlamydia Rapid Test with self collected vaginal swabs indicates that it would be an effective same day diagnostic and screening tool for Chlamydia infection in women. The availability of Chlamydia Rapid Test results within 30 minutes allows for immediate treatment and contact tracing, potentially reducing the risks of persistent infection and onward transmission. It could also provide a simple and reliable alternative to nucleic acid amplification tests in chlamydia screening programmes.     

A systemic microbial disease in the Dungeness crab,Cancer magister,caused by a Chlamydia-like organism

A Chlamydia-like agent was diagnosed in Dungeness crabs, Cancer magister, collected from Willapa Bay and northern Puget Sound, Washington. Over a 5-year period, infected crabs were found during the months of December through March. Infection by the organism is systemic, resulting in greatly hypertrophied cells with appressed nuclei. Unlike Chlamydia or other Chlamydia-like organisms, the present microbe has a great affinity for connective tissue or connective tissue cells rather than epithelial cells. Transmission electron microscopy revealed the presence of several developmental stages that are similar to chlamydial stages, in addition to what appear to be slightly altered or aberrant stages.     

Rab6 and Rab11 Regulate Chlamydia trachomatis Development and Golgin-84-Dependent Golgi Fragmentation

Many intracellular pathogens that replicate in special membrane bound compartments exploit cellular trafficking pathways by targeting small GTPases, including Rab proteins. Members of the Chlamydiaceae recruit a subset of Rab proteins to their inclusions, but the significance of these interactions is uncertain. Using RNA interference, we identified Rab6 and Rab11 as important regulators of Chlamydia infections. Depletion of either Rab6 or Rab11, but not the other Rab proteins tested, decreased the formation of infectious particles. We further examined the interplay between these Rab proteins and the Golgi matrix components golgin-84 and p115 with regard to Chlamydia-induced Golgi fragmentation. Silencing of the Rab proteins blocked Chlamydia-induced and golgin-84 knockdown-stimulated Golgi disruption, whereas Golgi fragmentation was unaffected in p115 depleted cells. Interestingly, p115-induced Golgi fragmentation could rescue Chlamydia propagation in Rab6 and Rab11 knockdown cells. Furthermore, transport of nutrients to Chlamydia, as monitored by BODIPY-Ceramide, was inhibited by Rab6 and Rab11 knockdown. Taken together, our results demonstrate that Rab6 and Rab11 are key regulators of Golgi stability and further support the notion that Chlamydia subverts Golgi structure to enhance its intracellular development.     

INAUGURAL MEETING OF THE NATIONAL FOSSIL ALGAE RESEARCH GROUP OF PSC AND THE 1ST FOSSIL ALGAE SYMPOSIUM HELD IN NANJING

The inaugural meeting of the National Fossil Algae Research Group of PSC and the l st fossil algae symposium were held from December 2-7, 1981 in Nanjing. 117 Chinese fossil algae of China", in which he gave an geological colleges, geological survey, petroleum prospecting units, coal and metallurgical in-     

CPAF: A Chlamydial Protease in Search of an Authentic Substrate

Bacteria in the genus Chlamydia are major human pathogens that cause an intracellular infection. A chlamydial protease, CPAF, has been proposed as an important virulence factor that cleaves or degrades at least 16 host proteins, thereby altering multiple cellular processes. We examined 11 published CPAF substrates and found that there was no detectable proteolysis when CPAF activity was inhibited during cell processing. We show that the reported proteolysis of these putative CPAF substrates was due to enzymatic activity in cell lysates rather than in intact cells. Nevertheless, Chlamydia-infected cells displayed Chlamydia-host interactions, such as Golgi reorganization, apoptosis resistance, and host cytoskeletal remodeling, that have been attributed to CPAF-dependent proteolysis of host proteins. Our findings suggest that other mechanisms may be responsible for these Chlamydia-host interactions, and raise concerns about all published CPAF substrates and the proposed roles of CPAF in chlamydial pathogenesis.     

Bioinformatic and biochemical evidence for the identification of the type III secretion system needle protein of Chlamydia trachomatis

Chlamydia spp. express a functional type III secretion system (T3SS) necessary for pathogenesis and intracellular growth. However, certain essential components of the secretion apparatus have diverged to such a degree as to preclude their identification by standard homology searches of primary protein sequences. One example is the needle subunit protein. Electron micrographs indicate that chlamydiae possess needle filaments, and yet database searches fail to identify a SctF homologue. We used a bioinformatics approach to identify a likely needle subunit protein for Chlamydia. Experimental evidence indicates that this protein, designated CdsF, has properties consistent with it being the major needle subunit protein. CdsF is concentrated in the outer membrane of elementary bodies and is surface exposed as a component of an extracellular needle-like projection. During infection CdsF is detectible by indirect immunofluorescence in the inclusion membrane with a punctuate distribution adjacent to membrane-associated reticulate bodies. Biochemical cross-linking studies revealed that, like other SctF proteins, CdsF is able to polymerize into multisubunit complexes. Furthermore, we identified two chaperones for CdsF, termed CdsE and CdsG, which have many characteristics of the Pseudomonas spp. needle chaperones PscE and PscG, respectively. In aggregate, our data are consistent with CdsF representing at least one component of the extended Chlamydia T3SS injectisome. The identification of this secretion system component is essential for studies involving ectopic reconstitution of the Chlamydia T3SS. Moreover, we anticipate that CdsF could serve as an efficacious target for anti-Chlamydia neutralizing antibodies.     

The association between sociodemographic,hormonal, tubo-ovarian factors and bacterial count in Chlamydia and Mycoplasma infections with infertility

Aim: To determine if there is an association between the Chlamydia and Mycoplasma infections with socio-demographic and clinical factors, and also with infertility. Methods: We conducted a study on 100 infertile married women and 100 control group, and collected data on the socio-demographic, hormonal and tubo-ovarian factors. The results of the endocervical swabs were analyzed for Mycoplasma and Chlamydia infection, the bacterial counts were also determined. Results: The percentage positivity to infection was significantly more among the infertile group compared to the control group, and also significantly more among the age group <30 years old. The positivity for infection with Chlamydia and/or Mycoplasma was significantly correlated with age, history of irregular menstruation, and history of previous abortion. Further sub-analysis of the infertile group showed that positivity to Chlamydia and/or Mycoplasma infection was significantly correlated to hormonal factors, ovarian factors, irregular menstruation, and previous abortion. Regression analysis showed that hormonal, ovarian factors, and irregular menstruation were the most significant factors in the positivity to Chlamydia and Mycoplasma infection. Bacterial count was significantly correlated with age, history of irregular menstruation, and history of previous abortion. Conclusion: Infection to Chlamydia and Mycoplasma is associated to younger age (?30 years old), and occurs in the infertile women. There is an interplay between infection in younger women, irregular menstruation, hormonal, and tubo-ovarian factors with infertility. Bacterial count was significantly correlated with age, history of irregular menstruation, and history of previous abortion.     

Toxoplasmosis: a persisting challenge

The sixth biennial International Congress on Toxoplasmosis, organized by Uwe Gross (University of Göttingen, Germany), was held on 21–25 May 2001 in Freising, Germany. The first meeting of this kind in 1990 was attended by only 26 investigators and this year there were 115 participants covering various research topics including the immunology, epidemiology, cellular and molecular biology of Toxoplasma gondii.