Publications by authors named "Sekhar Chakrabarti"

Background: Toll like receptors (TLRs) play an important role in innate immunity and various studies suggest that TLRs play a crucial role in pathogenesis of hepatitis B virus (HBV) infection. The present study aims in looking into the status of crucial host and viral gene expression on inciting TLR7.

Methods: The transcription of TLR7 pathway signaling molecules and HBV DNA viral load were quantified by Real Time-PCR after stimulation of TLR7 with its imiquimod based ligand, R837.

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Background: HIV estimates for 2009 released by National AIDS Control Organization (NACO) reveals that 2.4 million people in India were living with HIV, 39% being female, 4.4% children and 82.

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Article Synopsis
  • TNF-α promoter polymorphisms at positions -238 and -863 may serve as predictive factors for HBV infection outcomes in patients from East India.
  • A study involving 195 participants found that certain genotypes were significantly more common in HBV-infected individuals compared to controls, particularly the -238 GG and -863 CC genotypes.
  • The findings suggest that the -863CC genotype is linked to a negative association with the progression of liver disease, highlighting the relevance of these genetic markers in understanding HBV-related health issues.
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Background: Worldwide, frequent emergence of lamivudine (3TC)-resistant HBV mutants has been reported in HIV-HBV-coinfected patients during long-term antiretroviral therapy (ART) that contains 3TC as the sole anti-HBV drug. Three major patterns of mutations in HBV polymerase gene, namely single (rtM204V), double (rtL180M+rtM204V) and triple (rtV173L+rtL180M+rtM204V) mutations, are associated with 3TC-resistance; additionally, the triple mutation has vaccine-escape potential due to a corresponding change in overlapping surface gene. Data from India, a major reservoir for HIV and HBV infection, is lacking.

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Intra venous drug users (IVDUs) are at high risk for hepatitis C virus (HCV) infection owing to their high rate of drug abuses. The north-eastern part of India has a high prevalence of IVDUs with Manipur being the worst hit state. The aim of the study was to document the molecular epidemiology, the patterns of HCV transmission, genomic variation and recombination events within HCV genome among IVDUs of Manipur, India.

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Previously we reported that the exposure to hepatitis B virus (HBV) infection serves as a major threat among the treatment naive HIV infected population of eastern India. Hence, molecular characterization of these strains is of utmost importance in order to identify clinically significant HBV mutations. A total of 85 treatment naive HIV/HBV co-infected participants were included of whom the complete basal core promoter/precore region, the core and the whole envelope gene could be successfully sequenced for 59, 57 and 39 isolates respectively.

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Article Synopsis
  • - A study in West Bengal found a high rate of occult HBV infection (OBI) among blood donors who tested negative for HBsAg, with 24.25% of anti-HBc positive donors showing HBV DNA.
  • - Analysis revealed predominant HBV subgenotypes, especially HBV/D (87.23%), with a significant prevalence of the HBV/D3 subgenotype at 65.85%.
  • - Various mutations in the HBV strains were identified, raising concerns about their clinical relevance and association with OBI, suggesting the need for further research.
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We studied the prevalence and effects of host genetic polymorphisms for the three AIDS restriction genes (ARGs) namely CCR2-64I, SDF1-3'A and MCP1-2518 G/A for HIV infection and progression to AIDS using PCR-RFLP analysis on a total of 568 HIV seronegative serum samples collected from a specific high risk and young population hailing from the seven Northeastern states of India (n = 346), West Bengal (n = 96) and Gorkha population (n = 101). In addition, 181 HIV seropositive cases of which 92 inpatient cases in a large tertiary care hospital located at Kolkata were included in the study. HIV prevalence in our study group was 0.

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Background: Interleukin-1β (IL-1β) is an important member of the family of the proinflammatory cytokines that modulate outcome of hepatitis B virus (HBV) infection.

Objectives: This study was designed to investigate the relationship between the polymorphic genotypes of the interleukin-1β (IL-1β) promoter region and the interleukin-1 receptor antagonist gene (IL-1RN) and disease outcome in HBV-infected individuals.

Methods: DNA was extracted from 395 study subjects including HBV carriers with varying clinical presentations, as well as healthy controls and spontaneously recovered cases (SRC).

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Herpes genitalis, caused by HSV-2, is an incurable genital ulcerative disease transmitted by sexual intercourse. The virus establishes life-long latency in sacral root ganglia and reported to have synergistic relationship with HIV-1 transmission. Till date no effective vaccine is available, while the existing therapy frequently yielded drug resistance, toxicity and treatment failure.

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Article Synopsis
  • * Among the ART-naive patients, HBV was found to be more prevalent (11.3%) than HCV (1.9%), with a majority of HBeAg positive co-infected patients showing significantly higher HBV DNA levels.
  • * The findings suggest a higher prevalence of HIV/HBV co-infection, highlighting the importance of HBeAg testing for timely treatment and the need for monitoring even HBeAg negative patients due to their substantial HBV DNA levels.
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Chikungunya and dengue, two arboviral infections are common in South-East Asia and their early clinical manifestations are very similar hence it is important to discriminate between them as early as possible for better clinical management. The aim of this study was to design a rapid, sensitive and specific method for the differential diagnosis of these two viruses simultaneously. A rapid one-tube duplex RT-PCR assay was developed that requires 110 min including RNA extraction, RT-PCR and agarose gel electrophoresis by using a novel Taq polymerase with high processivity.

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Ethnopharmacological Relevance: Different parts of Indian ethnomedicinal plant Shorea robusta is traditionally used for several ailments including wounds and burn by different tribal groups, since ages. Here we have validated, for the first time, the effectiveness and the possible mechanism of action of young leaf extracts of Shorea robusta, used by two distinct tribes of India, and its isolated compounds as a topical formulation in three wound models in rats.

Materials And Methods: Bioactivity-guided study of the active extract resulted in the isolation of two known compounds.

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HIV-1 replication is a tightly controlled mechanism which demands the interplay of host as well as viral factors. Both gp120 (envelope glycoprotein) and Nef (regulatory protein) have been correlated with the development of AIDS disease in independent studies. In this context, the ability of HIV-1 to utilize immature dentritic cells for transfer of virus is pivotal for early pathogenesis.

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Article Synopsis
  • * In a study of 147 HBsAg positive patients, various HBVrt mutations were found in both treatment naïve (65%) and treated patients (56.2%), indicating a potential for reduced drug efficacy.
  • * The presence of certain mutations linked to drug resistance was common in non-responders and naïve patients, but classical antiviral resistance mutations were not detected, suggesting further investigation is needed to understand their impact on current treatments.
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We have investigated the molecular diversity of Hepatitis B virus (HBV) among the HIV co-infected patients from eastern-India. HBsAg/HBV-DNA positive subjects (n=73) from 874 HIV-infected patients were analyzed by sequencing followed by genetic diversity quantification. HBV/genotype-D and HBV/sugenotype-D2 were predominant.

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Background: Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen, is the sole etiologic agent of Japanese Encephalitis (JE); a neurotropic killer disease which is one of the major causes of viral encephalitis worldwide with prime public health concern. JE was first reported in the state of West Bengal, India in 1973. Since then it is being reported every year from different districts of the state, though the vaccination has already been done.

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Background: During the pandemic [Influenza A(H1N1)pdm09] period in 2009-2010, an influenza A (Inf-A) virus with H1N2 subtype (designated as A/Eastern India/N-1289/2009) was detected from a 25 years old male from Mizoram (North-eastern India).

Objective: To characterize full genome of the H1N2 influenza virus.

Methods: For initial detection of Influenza viruses, amplification of matrix protein (M) gene of Inf-A and B viruses was carried out by real time RT-PCR.

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Background: The AIDS epidemic in Manipur, India, manifests unique features, having co-circulation of B and C HIV-1 subtypes along with recombinant forms. Manipur has the highest incidence of HIV-1 infection compared to the other states of India, but limited information is available regarding the full-length sequence of HIV-1 recombinants.

Objectives: To characterize the near full-length genome of a novel recombinant HIV-1 strain from an injecting drug user of Manipur.

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The study was undertaken to investigate the clinical implications of hepatitis B virus (HBV) genotypes, basal core promoter (BCP), precore (PC) and surface gene mutations in HBV infected patients from Orissa, southeastern India. HBV infections were identified by serology testing and HBV DNA amplification by polymerase chain reaction among the 152 patients. After sequencing, surface gene mutation were studied by sequence analysis as well as by using BLOSUM scores and BCP mutations were studied only by sequence analysis.

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Genetic complexity of HIV-1 is brought about by recombination between HIV-1 subtypes which leads to the development of epidemiologically significant founder strains. In the present study, the near full-length genome sequence of an HIV-1 isolate from an injecting drug user of Manipur (India) was determined, which evidenced the presence of a novel HIV-1 BC recombinant strain. Near full-length genome was amplified by polymerase chain reaction using primer walking approach.

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The authors report a case of a 47-year-old cytomegalovirus (CMV) immunoglobulin G (IgG) seropositive male patient with end stage renal disease who received a live renal transplant from a CMV IgG seropositive donor. Six months post-transplantation, the patient presented with reduced renal allograft function associated with fever, severe breathlessness, new onset jaundice and pancytopenia. His CMV DNA PCR came positive.

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The presence of three different HBV genotypes (A, C and D) in Eastern India provided us a unique opportunity to study HBV pre-S mutants in these genotypes and subtypes among the same ethnic population. Furthermore, we also aimed to investigate the association of the HBV pre-S mutation with clinical outcome. Pre-S1-S2 and S gene was amplified and sequenced from 86 HBsAg positive study subjects with varying clinical manifestation.

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Background: Influenza A virus encodes for eleven proteins, of which HA, NA, NS1 and PB1-F2 have been implicated in viral pathogenicity and virulence. Thus, in addition to the HA and NA gene segments, monitoring diversity of NS1 and PB1-F2 is also important.

Methods: 55 out of 166 circulating influenza A strains (31 H1N1 and 24 H3N2) were randomly picked during 2007-2009 and NS and PB1-F2 genes were sequenced.

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Background: Human immunodeficiency virus (HIV) antigens from transmitted strains of HIV would prove crucial in vaccine designing for prevention of HIV infection. Immune response generated by Vaccinia construct expressing the HIV-1 gag gene from transmitted Indian HIV-1 subtype C strain (Vgag) in BALB/c mice is reported in the present study along with the identification of epitopes responsible for induction of the immune response.

Aims: The aim of this study was to determine immune response generated by the constructs in a mouse model and to understand the epitope specificities of the response.

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