Role of toll-like receptors in immune responses to chlamydial infections.

Chlamydiae are important human pathogens which are leading causative agents for a variety of disease conditions including ocular, respiratory and sexually transmitted diseases, thus causing significant morbidity worldwide. Many of the human diseases caused by Chlamydia species are considered to be immunopathologically mediated. Toll like receptors (TLRs) have emerged as one of the major components of the immune system. Recognition of pathogen associated molecular patterns (PAMPs) by TLRs results in the activation of signaling events that induce the expression of effector molecules such as cytokines and chemokines which control the activation of adaptive immune responses. The precise immune mechanisms involved in resistance or pathogenesis to chlamydial infection, especially in the TLR signaling and downstream events during the innate phase of infection initiating the adaptive immune responses remains largely unknown. This review focuses on elaborating the current knowledge on the role of TLRs in immune responses to chlamydial infection. Although chlamydial components like lipopolysaccharide (LPS) and chlamydial heat shock protein 60 (cHSP60) are recognized by TLR4, the intact organisms stimulates the innate immune cells through TLR2, which also plays an important role as a PRR for Chlamydia. While the individual role of different TLRs such as TLR2, TLR4 and TLR9 in chlamydial infection is becoming delineated, studies have demonstrated the essential role of the TLR adapter molecule MyD88 in the generation of immune responses to Chlamydia infection. Given that there is no effective vaccine available for Chlamydia till date, a better understanding of the immunological and molecular mechanisms mediated by TLRs will greatly aid in possibly exploiting these molecules as immunotherapeutic targets.

Diagnostic utility of serologic markers for genital chlamydial infection in STD patients in Chennai, India.

OBJECTIVES: To evaluate the diagnostic utility of serological markers for C. trachomatis in different clinical groups of STD patients. METHODS: Blood and genital swab specimens were collected from symptomatic STD patients (n=143) attending the STD out patient clinic at the Institute of STDs, Government General hospital, Chennai who enrolled for the study. Serological determination for IgM, IgA and IgG antibodies to C. trachomatis was done using commercial kits. PCR analysis was performed on genital swab samples by using plasmid and major outer membrane protein (MOMP) based primers and patients who were positive by both PCR assays were considered as proven cases of C. trachomatis infection. The serological marker positivity was analysed with PCR positivity. RESULTS: Serologic positivity by IgM, IgA and IgG was 22.4%, 28.7% and 58.7% respectively. The PCR analysis showed 44 (30.8%) cases with confirmed C. trachomatis infection. Seropositivity for IgM (34.1% (15/44) vs. 17.2% (17/99); P<0.05) as well as for IgA (40.9% (18/44) vs. 23.2% (23/99); P<0.05) significantly correlated to PCR positivity, while significant correlation was not seen with IgG positivity. The overall seropositivity (IgM/IgA/IgG) in the study population was 68.5%. CONCLUSIONS: The observations of the present study indicate a high exposure rate to chlamydial infection in STD clinic patients in India. The study also suggests the usefulness of serology instead of PCR to trace chlamydial etiology, especially in deep-seated upper genital tract diseases and to facilitate better clinical management as there was good correlation between serology and PCR positivity.

Genital chlamydial infection in STD patients: its relation to HIV infection.

In the present report, we have analysed C.trachomatis infection and HIV positivity among patients (n-143) who attended the STD clinic at the Institute of STDs, Government General Hospital, Chennai. HIV positivity rate was significantly high among those with chlamydial infection than in those without chlamydial infection (29.5% (13/44) vs. 11.1% (11/99); p<0.05). The results of the present study suggest the association between C.trachomatis and HIV infections and reinforce the need for routine screening for C.trachomatis as a necessary intervention to reduce the burden of chlamydial diseases and to reduce the risk of HIV and its spread in India.

Detection of Enterocytozoon bieneusi (Microsporidia) by polymerase chain reaction (PCR) using species-specific primer in stool samples of HIV patients.

BACKGROUND & OBJECTIVE: Microsporidia are obligate intracellular parasites causing infections predominantly in immunocompromised patients. Enterocytozoon bieneusi is the most important microsporidian causing chronic diarrhoea in AIDS patients. The current method used for diagnosing the microsporidia spores is based on light microscopy using stained smears, which do not differentiate spores at species level. The present study was undertaken to detect microsporidia and confirm at species level (E. bieneusi) by PCR from stool samples of HIV positive patients. METHODS: During September 2002 to April 2003, stool samples from 153 HIV-positive patients (with chronic diarrhoea n = 105; without diarrhoea n=48) were collected and examined microscopically for microsporidia spores using modified Weber's chromotrope stain. Stool samples were subjected to PCR assay using species-specific primer EBIEFI/EBIER1, which amplifies small subunit ribosomal RNA (SSU rRNA) of this microsporidian RESULTS: A total of 10 HIV positive patients with chronic diarrhoea were positive for microsporidia by microscopic analysis and confirmed as Enterocytozoon bieneusi by PCR. No false positive results were observed. A diagnostic DNA fragment of 607 bp of the unique SSU rRNA was amplified from all samples infected with E. bieneusi. INTERPRETATION & CONCLUSION: The study revealed that polymerase chain reaction is a useful tool for accurate species identification of microsporidia in stool samples, which serves the benefit of treatment to the patients.

Effect of L-carnitine on nucleic acid status of aged rat brain.

The accumulation of damage to DNA plays a significant role in the etiology of the aging process. The importance of nutrition in delaying the aging process is well recognized. L-carnitine is a quaternary ammonium compound heterogeneously distributed in the brain. In the present study the effect of L-carnitine on DNA damage of various brain regions was investigated in a duration dependent way. Male albino rats aged 4 and 24 months were administered L-carnitine (300 mg/kg body weight/day) for 7,14 and 21 days. The activities of antioxidant enzymes, the levels of nucleic acids and the extent of DNA damage were measured in cortex, hippocampus, striatum, hypothalamus and cerebellum. Our results clearly showed that the activities of super oxide dismutase, glutathione peroxidase and the levels of DNA and RNA were significantly low in cortex, hippocampus and striatum of aged rat brain when compared with that of young rats. The regions that have lower antioxidants status are highly susceptible to oxidative DNA damage. Treatment with L-carnitine in aged rats enhanced the nucleic acid, antioxidant activity in a duration dependent manner with maximal effect after 21 days whereas no significant changes could be observed in the brain of young rats. These results suggest that that L-carnitine administration prevents age-related increment of DNA damage, thereby confirming the neuroprotective action of L-carnitine against aging.

Chlamydia trachomatis genital infection in apparently healthy adult population of Tamil Nadu, India: a population-based study.

Since the epidemiology of Chlamydia trachomatis infection in apparently healthy population has not been studied in India, a population-based study was conducted in the state of Tamil Nadu, India in order to analyse the prevalence of genital chlamydial infections in the community and to implement control programmes. A representative sample was taken from three randomly selected districts by using the 'probability proportional to size' cluster survey method. Households were the basic units of clusters. Adults aged 15-45 years, pre-identified from the selected households were enrolled during the medical camps conducted for a major study on community prevalence of sexually transmitted diseases in Tamil Nadu. Blood and urine samples collected from the study subjects were tested by enzyme-linked immunosorbent assay (ELISA) for anti-chlamydial IgM antibodies and by the commercial Amplicor polymerase chain reaction (PCR) test for chlamydial DNA. The prevalence of anti-C. trachomatis antibodies determined by IgM-ELISA was 2.4% (95% CI 1.6%-3.2%). The prevalence of genital chlamydial infection determined by PCR was 1.1% (95% CI 0.5%-1.7%). Majority of the detected infections (68.8%) were asymptomatic. This is the first Indian report on the prevalence of genital chlamydial infections in the general population. It is concluded that this study provides evidence for a substantial burden of approximately 10 million asymptomatic genital chlamydial infection cases in the sexually active age groups in the general population of India.

Need for specific & routine strategy for the diagnosis of genital chlamydial infection among patients with sexually transmitted diseases in India.

BACKGROUND & OBJECTIVES: With increasing burden of human immunodeficiency virus (HIV) infection acquired immunodeficiency syndrome (AIDS) in India, documentation on the epidemiology of genital chlamydial infections in high-risk patients with sexually transmitted diseases (STD) is of significant public health value. Specific diagnosis is essential to prevent the morbidity due to the chlamydial infection and to reduce the risk of acquiring HIV infection. The present study was undertaken to analyse the usefulness of culture and antigen detection by direct fluorescent antibody (DFA) test for assessing the rate of Chlamydia trachomatis infection in symptomatic patients and feasibility of these tests for routine adoption in Indian setting. METHODS: Clinically diagnosed patients of both sex (n=143) attending the Institute of Sexually Transmitted Diseases, Government General Hospital, Chennai who consented for the study, were enrolled. Clinical and demographic details were recorded on a stratified proforma. Genital swab specimens collected from them were subjected for culture using McCoy cell line and for antigen detection by DFA testing. RESULTS: C. trachomatis was isolated in 27 of the total 143 patients (18.9%). Culture positivity was seen in 11 of the 63 (17.5%) males and in 16 of 80 (20%) females. DFA detected C. trachomatis specific antigen in 35 patients (24.5%); 15 (23.8%) males and 20 (25%) females. The rate of C. trachomatis diagnosis increased to 25.2 per cent by adopting both the methods as against 18.9 per cent by culture only and 24.5 per cent by DFA only. No association of C. trachomatis infection with any predictable genitourinary symptom (s), was seen. INTERPRETATION & CONCLUSION: The findings show a high infection rate for C. trachomatis in symptomatic patients with STD. Clinical symptoms alone can be unreliable in specifically predicting infections with C. trachomatis. Specific diagnostic tests need to be recommended for routine inclusion in the STD diagnosis to facilitate risk reduction of HIV infection in STD patients.

Serodiagnosis of syphilis in a community: an evaluatory study.

PURPOSE: To analyse the prevalence of syphilis in the apparently healthy population and to provide data for implementation of the joint STD/HIV control programme, a population based study was undertaken by using 'probability proportional to size' cluster survey method in three randomly chosen districts of Tamil Nadu, India namely Dindigul, Ramnad and Tanjore. METHODS: Blood samples were collected from adults (n=1873) aged 15-45 years, from the selected households enrolled in this study. The sera were tested parallelly by rapid plasma reagin (RPR) and Treponema pallidum haemagglutination (TPHA) tests. Reactive samples by RPR and/or TPHA were later analysed by fluorescent treponemal antibody absorption (FTA-ABS) test. RESULTS: The prevalence of syphilis in the community of Tamil Nadu as per RPR positivity was 2.7% (50/1873) as against 0.7% by TPHA (13/1873). FTA-ABS positivity was observed in only 12 out of 48 (25%) RPR/TPHA reactive samples tested. By taking the positivity by two of the three tests, the community prevalence of acute ongoing syphilis in Tamil Nadu was determined as 1.1% (20/1873). CONCLUSIONS: The results confirmed that no single serological test for syphilis can act as the marker of ongoing acute infection in an apparently healthy population. The study suggests that for specific diagnosis of ongoing syphilis, the FTA-ABS test may be performed along with RPR and TPHA.

Community prevalence of sexually transmitted diseases and human immunodeficiency virus infection in Tamil Nadu, India: a probability proportional to size cluster survey.

BACKGROUND: Human immunodeficiency virus (HIV) infection and AIDS is threatening the survival of many nations. To evaluate ongoing interventional strategies and burden of illness estimates, valid data on the prevalence of HIV are required. Often, in the absence of community prevalence data, estimates are based on surrogate markers such as prevalence of HIV in antenatal clinics. Even though the antenatal prevalence of HIV is easier to measure and can be repeated for evaluation, it is important to establish the association between antenatal and community prevalence of sexually transmitted diseases (STDs) and HIV, so that the validity of the estimates can be verified. METHODS: A 'probability proportional to size' cluster survey was conducted in three randomly selected districts of Tamil Nadu in India. The basic unit of the survey was households from rural and urban clusters. Adults 15-45 years of age from the selected households were eligible for recruitment. Demographic, behavioural and laboratory data were collected. Clinical examination was done to identify STD syndromes and blood, urine, vaginal/urethral and endocervical swabs were taken for laboratory diagnosis of STDs from the subjects. Direct smear examination for Trichomonas vaginalis; serological tests for syphilis, hepatitis B, HIV, herpes simplex virus 2, Chlamydia trachomatis; and culture of Neisseria gonorrhoeae and Haemophilus ducreyi were performed on the collected specimens. The data were analysed adjusting for cluster effect. RESULT: We selected and screened 1981 individuals (1157 women and 824 men) for STDs and HIV from 1114 households representing the 25 million projected adult population of Tamil Nadu. The overall community prevalence of STDs including HIV and hepatitis B in Tamil Nadu was 14.6% (CI: 14.1-15.1), and 8.3% (CI: 7.9-8.6) when HIV and hepatitis B were excluded. Community prevalence of HIV and hepatitis B infection was 1.8% (CI:1.7-1.9) and 5.3% (CI: 5.1-5.5), respectively. The distribution of HIV involved both rural and urban regions of Tamil Nadu. On clinical examination, at least one STD syndrome was noted in 486 (24.5%) of the women subjects; vaginal discharge was the most common and found in 421 women (38.4%). CONCLUSION: The prevalence of STD and HIV in Tamil Nadu is higher than expected and has extended into the non-high risk population (generalized epidemic).

Asymptomatic malarial parasitaemia in Tamil Nadu.

AIM: The aim of the study was to determine the community prevalence of asymptomatic malarial parasitaemia in the state of Tamil Nadu. METHODS: Free medical camps were organised in three randomly selected districts of Tamil Nadu, namely Dindigul, Ramnad and Thanjavur districts in November, 1997. Proportionate to population size cluster survey method was followed to collect peripheral blood smear by finger prick from 30 clusters in each district. Fifteen households were randomly selected from each district with the target age group of 15-45 years. Peripheral blood smears were stained by Leishman's stain and the slides were examined end to end by two independent experts to diagnose malarial parasites. RESULTS: The male:female ratio of the population studied was 1:1.6. Asymptomatic malaria was identified in 17 out of 569 individuals screened with a positive rate of 2.9% (CI 1.5-4.3). Out of the 17 malarial positive peripheral smears 15 were P. vivax and only two were P. falciparum with the predominance of gametocyte stage. CONCLUSION: This study reaffirms the prevalence of asymptomatic malaria in Tamil Nadu especially with P. vivax.