Epidemiological and clinical aspects on West Nile virus, a globally emerging pathogen.

BACKGROUND: Since the isolation of West Nile virus (WNV) in 1937, in Uganda, it has spread globally, causing significant morbidity and mortality. While birds serve as amplifier hosts, mosquitoes of the Culex genus function as vectors. Humans and horses are dead end hosts. The clinical manifestations of West Nile infection in humans range from asymptomatic illness to West Nile encephalitis. METHODS: The laboratory offers an array of tests, the preferred method being detection of RNA and serum IgM for WNV, which, if detected, confirms the clinical diagnosis. Although no definitive antiviral therapy and vaccine are available for humans, many approaches are being studied. STUDY: This article will review the current literature of the natural cycle, geographical distribution, virology, replication cycle, molecular epidemiology, pathogenesis, laboratory diagnosis, clinical manifestations, blood donor screening for WNV, treatment, prevention and vaccines.

Effect of HIV-1 Subtype C integrase mutations implied using molecular modeling and docking data.

The degree of sequence variation in HIV-1 integrase genes among infected patients and their impact on clinical response to Anti retroviral therapy (ART) is of interest. Therefore, we collected plasma samples from 161 HIV-1 infected individuals for subsequent integrase gene amplification (1087 bp). Thus, 102 complete integrase gene sequences identified as HIV-1 subtype-C was assembled. This sequence data was further used for sequence analysis and multiple sequence alignment (MSA) to assess position specific frequency of mutations within pol gene among infected individuals. We also used biophysical geometric optimization technique based molecular modeling and docking (Schrodinger suite) methods to infer differential function caused by position specific sequence mutations towards improved inhibitor selection. We thus identified accessory mutations (usually reduce susceptibility) leading to the resistance of some known integrase inhibitors in 14% of sequences in this data set. The Stanford HIV-1 drug resistance database provided complementary information on integrase resistance mutations to deduce molecular basis for such observation. Modeling and docking analysis show reduced binding by mutants for known compounds. The predicted binding values further reduced for models with combination of mutations among subtype C clinical strains. Thus, the molecular basis implied for the consequence of mutations in different variants of integrase genes of HIV-1 subtype C clinical strains from South India is reported. This data finds utility in the design, modification and development of a representative yet an improved inhibitor for HIV-1 integrase.

Frequency of transmitted drug resistance mutations among treatment-naïve HIV-1-infected individuals at a tertiary care centre in South India.

INTRODUCTION: Morbidity and mortality among HIV-1-infected individuals has been dramatically reduced by the implementation of combinational antiretroviral therapy (ART). However, the efficiency of these therapies is compromised due to HIV-1 transmitted drug resistance mutations (TDRMs). METHODS: We collected a total of 127 samples from ART-naïve HIV-infected individuals and sequenced the pol gene and analysed for drug resistance mutations using the Calibrated Population Resistance (CPR) tool in the Stanford database. RESULTS: All the 127 clinical samples (100 %) were identified as HIV-1 subtype C. Based on the CPR tool, three strains (2.4 %) had TDRMs, and these were K101E, Y181C and G190A. Our findings correlated well with the WHO surveys conducted in Asia, including India, which consistently reported <5 % TDRM among the specific populations assessed. CONCLUSION: In countries like India, regular monitoring of TDRMs will provide better information for clinical practice improvement and policy making.

HIV-1 seroprevalence and awareness of mother-to-child transmission issues among women seeking antenatal care in Tamil Nadu, India.

BACKGROUND: Despite increasing availability of HIV-1 testing, education, and methods to prevent transmission, Indian women and their children remain at risk of acquiring HIV. We assessed the seroprevalence and awareness about HIV among pregnant women presenting to a private tertiary care hospital in South India. METHODS: Seroprevalence was determined via enzyme-linked immunosorbent assay (ELISA) testing, and questionnaires were analyzed using chi-square statistics and odds ratios to look for factors associated with HIV positivity. RESULTS: A total of 7956 women who presented for antenatal care were interviewed. Fifty-one women of the 7235 women who underwent HIV testing (0.7%) were found to be HIV positive. Awareness of mother-to-child transmission (MTCT) of HIV (64%), HIV transmission through breast milk (42%), and prevention of MTCT (13%) was low. CONCLUSIONS: There is a need to educate South Indian women about HIV to give them information and the means to protect themselves and their unborn children from acquiring HIV.

Performance of a rapid immunochromatographic screening test for detection of antibodies to human immunodeficiency virus type 1 (HIV-1) and HIV-2: experience at a tertiary care hospital in South India.

The performance characteristics of a rapid immunochromatographic-screening test, SD Bioline HIV-1/2 3.0 (Standard Diagnostics Inc., Kyonggi-do, South Korea) on 23,754 sera and 30 plasma samples are reported. The sensitivity and specificity for the assay on serum samples are 100% and 99.4%, respectively. The assay detected antibodies in individuals infected with human immunodeficiency virus type 1 (HIV-1) genotypes A and C and HIV-2. This straightforward assay is a reliable diagnostic tool for screening HIV in resource-poor settings.

Molecular epidemiology of HIV.

The phylogenic analysis of the nucleotide sequences of the env gene has enabled classification of HIV-1 into three groups. The group M of HIV-1 infection has been classified into 9 different genetic subtypes A-K, with E and I being classified as circulating recombinants forms (CRFs). The groups O and N are less frequently encountered in human infections. Presently group M of HIV-1 globally causes 99.6 per cent of all human infections. The epidemiological trends suggest that subtype C strains would dominate the HIV pandemic in the coming years. The geographic spread of subtype C strains is also very diverse with prevalence in Africa, Latin America and Asia. Data from India show a high prevalence of subtype C. In north and western India, 78.4 and 96 per cent of HIV-1 strains respectively were shown to be subtype C. Among female sex workers in Kolkata 95 per cent of the HIV-1 strains were subtype C. The south Indian subtype data are very similar to the data from the rest of India. The HIV-2 groups (subtypes) recognized are A-H. Unlike HIV-1, HIV-2 strains are predominantly found in Africa. The Indian HIV-2 strains identified till date are subtype A. This is also the predominant strain circulating in western African countries. This group (subtype) is estimated to cause 0.11 per cent of all HIV infections in humans.