Nucleos(t)ide analogues causes HBV S gene mutations and carcinogenesis

BACKGROUND： The long-term use of nudeos（t）ide analogues causes drug resistance and mutations in the HBV reverse tran- scriptase （RT） region of the polymerase gene. The RT region overlaps the HBV surface gene （S gene） and therefore, the mutations in the RT region simultaneously modify S gene sequence. Certain mutations in the RT region bring about truncated S proteins because the corresponding changed S gene encodes a stop codon which results in the loss of a large portion of the C-terminal hydrophobic region of HBV surface protein. The rtA181T/sW172＊, rtM204I/sW196＊ and rtV191I/sW182＊ are the most frequently reported drug-resistant mutations with C-terminal truncation, these mutations have oncogenic potential. DATA SOURCES： PubMed and Web of Science were searched using terms： ＂hepatitis B virus＂, ＂HBV drug resistance mutation＂ ＂HBV surface protein＂ ＂HBV truncation＂, ＂hepatocellular carcinoma＂, ＂rtA181T/sW172＊＂, ＂rtM204I/sW196＊＂, ＂rtV191I/sW182＊＂, and relevant articles published in English in the past decades were reviewed. RESULTS： The rtA181T/sW172＊ and rtV191I/sW182＊ mutants occurred more frequently than the rtM204I/sW196＊ mutant both in chronic hepatitis B patients and the HBV-related hepatocellular carcinoma tissues. Although these mutations occur naturally, nudeos（t）ide analogues therapy is the main driving force. These mutations may exist alone or coexist with other HBV mutations. All these three mutants impair the virion secretion and result in HBV surface protein retention and serum HBV DNA level reduction. These mutations possess potential carcinogenic properties. The three mutations are resistant to more than one nucleos（t）ide analogue and therefore, it is difficult to treat the patients with the truncated mutations.CONCLUSIONS： Nucleos（t）ide analogues induce drug resistance and HBV S gene truncated mutations. These mutations have potential carcinogenesis.

Pattern of HIV-1 Drug Resistance among Adults on ART in Nigeria

Background: The development of anitiretroviral drug resistance may limit the benefit of antiretroviral therapy. Therefore the need to closely monitor these mutations, especially the use of ART is increasing. This study was therefore designed to determine the ARV drug resistance pattern among ART na?ve and expose individuals attending a PEPFAR supported by antiretroviral clinic in Nigeria. Methodology: The study participants included patients attending the PEPFAR supported by University College Hospital (UCH), Ibadan ART clinic who have been on HIV treatment for at least one year with consecutive viral load of over 2000 copies/ml as well some ART Na?ve individuals with high (>50,000 copies/ml) baseline viral level attending the hospital for pre-ART assessment. Blood sample was collected from each individual for CD4 enumeration, viral load level determination and DNA sequencing for genotypic typing. Antiretroviral drug resistance mutations (DRM) were determined by using the Viroseq software and drug mutations generated by using a combination of Viroseq and Stanford algorithm. DRM were classified as major or minor mutations based on the June 2013 Stanford DR database. Results: The most common major NRTI, NNRTI and PI mutation were D67N (33.3%), Y181C (16.7%) and M46L/I (55.6%) respectively. Lamivudine (3TC) and emtricitabine (FTC);nevirapine (NVP) and nelfinavir (NFV) were the most common NRTI, NNRTI, and PI drugs to which the virus in the infected individuals developed resistance. Isolates from 4 patients were resistant to triple drug class, including at least one NRTI, NNRTI and a PI. Only one (4.8%) of the isolates from drug Na?ve individuals had major DRM that conferred resistance to any drug. Conclusion: Demonstration of high rates of antiretroviral DRM among patients on 1st and 2nd line ART and the presence of DRM in drug Na?ve individuals in this study show the importance of surveillance for resistance to ARV in line with the magnitude of scaling up of treatment program in the country.

High Frequency of Antiviral Resistance Mutations in HBV Genotypes A2 and H: Multidrug Resistance Strains in Mexico

Background and Aims:Lamivudine(3TC),telbivudine(LdT),entecavir(ETV),adefovir(ADF),and tenofovir(TFV)are drugs used to treat hepatitis B virus(HBV)infection,but specific mutations allow some viruses to become resistant to antiviral drugs or to acquire immune escape capacities.These mutations have not been thoroughly investigated in Mexico.This study aimed to estimate the prevalence of HBV antiviral resistance and escape mutations.Methods:This cross-sectional study analyzed 158 samples.HBV DNA was extracted,amplified,and sequenced in serum samples using the spin column method,PCR assay,and Sanger’s sequencing,respectively.HBV genotypes were determined,and HBV mutations were tested using the Geno2pheno tool.Results:Overall,68.4%(108/158)of HBV patients were infected with genotype H,followed by G(11.4%,18/158),A2(10.8%,17/158),F1b(6.9.0%,11/158),D(1.9%,3/158),and E(0.6%,1/158),and 5.1%(8/158)had evidence of recombination.The prevalence of resistance mutations was 8.2%(13/158)and the most common combined mutation was rt180M+rt204V.Notably,we found the combinations rt180M+rt204V+rt173L(n=2)and rt180M+rt204V+rt202G(n=1)that confer multidrug resistance to 3TC,LdT,and ETV.Resistance mutations were found in genotypes A2(11.8%,2/17),and H(10.2%,11/108),and escape mutations were detected in HBV genotypes A2(11.8%,2/17),H(10.2%,11/108),F1b(9.1%,1/11)and G(5.6%,1/18).Conclusions:The highest prevalence of antiviral resistance mutations or escape mutations was detected in HBV genotypes A2 and H.The earliest cases of HBV multidrug resistance were detected in Mexico.