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Background and Objectives: A virus population often exists as a complex mixture of genetic populations. Antiviral-resistant mutants could be circulating as minority variants in the mixed virus population that are not detected by standard sequencing methods. The role of minor drug-resistant variants and clinical outcome is slowly evolving and there is a need to employ sensitive methods for detection of minority variants that emerge as dominant species and subsequently affect the antiviral efficacy. This study was intended to develop a technique called the ligation amplification assay (LigAmp) to identify minor drug-resistant variants of hepatitis B virus (HBV). Methods: A LigAmp HBV assay was developed and clinical samples were tested from chronic hepatitis B subjects on antiviral treatment. Nucleotide sequencing of HBV reverse transcriptase (rt) region was performed and the results were compared with LigAmp assay. The performance of LigAmp assay was validated by clonal sequencing. Virological response was measured using HBV DNA levels and the results were correlated with antiviral-resistant mutations detected by sequencing and LigAmp assays. Results: A total of 80 reactions of LigAmp assay were performed for rtM204V and rtM204I (ATT) mutant detection. Samples were obtained from 40 chronic hepatitis B subjects. Among these subjects, rtM204V and rtM204I (ATT) mutations were identified by standard sequencing in 10 (25 %) and 12 (30 %) subjects, respectively. LigAmp detected both rtM204V and rtM204I (ATT) mutations in 13 (32.5 %) subjects, rtM204I mutation in 12 (30 %) subjects and rtM204V mutation in 1 (2.5 %) subject, respectively. LigAmp detected primary resistant mutants in 69.4 % of lamivudine non-responders while sequencing detected resistant mutations in only 55.6 % subjects ( p < 0.001). Conclusions: This data shows significantly higher sensitivity of LigAmp for detection of minority rtM204V and rtM204I (ATT) mutations over standard sequencing. Therefore, LigAmp has potential clinical utility for appropriate monitoring and tailoring of HBV therapy. [ABSTRACT FROM AUTHOR]

Background and objective: Management of chronic hepatitis B is a global public health challenge. There are several updated guidelines proposed based on treatment outcome data from the respective study populations. In this study, we aim to characterize the antiviral resistance mutations to lamivudine monotherapy in patients diagnosed with chronic hepatitis B from the Indian subcontinent. Methods: A total of 147 lamivudine-treated patients with a median treatment duration of 13 (interquartile range 8-24) months were studied. Virological response was measured by hepatitis B virus (HBV) DNA levels. Antiviral resistance mutations were identified by sequencing HBV reverse transcriptase domains. Factors associated with virological response and antiviral resistance mutations were analyzed. Results: Virological response was observed in 50 (35 %) patients while 84 (57 %) were non-responders. The virological response for the remaining 13 (9 %) patients was undetermined. Forty patients (27 %) developed lamivudine-resistant mutations. HBV genotypes, subgenotypes and hepatitis B surface antigen subtypes did not show significant association with virological response or lamivudine-resistant mutations. High HBV DNA levels and increased treatment duration were strongly associated with the development of lamivudine-resistant mutations ( p = 0.002 and p < 0.001). Patients who continued to be positive for hepatitis B e antigen have an increased risk for treatment failure ( p = 0.010). High baseline aspartate transaminase levels were significantly associated with subsequent lamivudine response ( p = 0.037). Conclusion: Considering the limited potency and high resistance rates to lamivudine therapy, our study emphasizes the use of more potent drugs in the management of chronic hepatitis B in the Indian subcontinent. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Through exomic sequencing of ten hepatitis C virus (HCV)-associated hepatocellular carcinomas (HCC) and subsequent evaluation of additional affected individuals, we discovered novel inactivating mutations of ARID2 in four major subtypes of HCC (HCV-associated HCC, hepatitis B virus (HBV)-associated HCC, alcohol-associated HCC and HCC with no known etiology). Notably, 18.2% of individuals with HCV-associated HCC in the United States and Europe harbored ARID2 inactivation mutations, suggesting that ARID2 is a tumor suppressor gene that is relatively commonly mutated in this tumor subtype. [ABSTRACT FROM AUTHOR]

Abstract: Entecavir is one of the therapeutic options currently available for the management of chronic hepatitis B. In this study, we aimed to analyse the virological response and antiviral resistance mutations in chronic hepatitis B subjects experiencing entecavir therapy from the Indian subcontinent. A total of 45 chronic hepatitis B subjects were studied at baseline and were followed up on entecavir treatment. Among these subjects, 25 (56%) were HBeAg-positive at baseline. Virological response was measured by hepatitis B virus (HBV) DNA levels. HBV reverse transcriptase (rt) domains were sequenced for the identification of resistance mutations. Three-Dimensional (3D) model of HBV polymerase/rt protein, docking and molecular dynamics simulation (MDS) studies were performed for characterization of antiviral resistance mutations. At the median treatment duration of 6 (IQR 6–11) months, 38 (84%) showed virological response. Subjects who showed anti-HBe response demonstrated significant association with virological response (p =0.034). On sequence analysis, none of the subjects were identified with signature entecavir resistance mutations. However, one subject was exclusively detected with rtV173L mutation. Molecular modeling, docking and MDS studies revealed that the rtV173L mutation cannot confer resistance to entecavir independently. Our findings also showed that the prevailing HBV genotypes, subgenotypes and HBsAg subtypes in this population does not influence treatment outcome to entecavir therapy. In conclusion, entecavir is a potent drug in terms of viral DNA suppression. In addition, none of the subjects developed antiviral resistance mutations to entecavir. Therefore entecavir is a suitable drug of choice in the management of chronic HBV. [Copyright &y& Elsevier]