Mutation in the hepatitis B virus surface antigen (HBsAg) may affect the efficiency of diagnostic immunoassays or success of vaccinations using HBsAg. Thus, antigenicity and immunogenicity analyses of the mutated HBsAg are necessary to develop novel diagnostic tools and efficient vaccinations. Here, the in vitro antigenicity of three wild-type HBsAg open reading frames (ORFs) (adr4, W1S [subtype adr] and W3S [subtype adr]) isolated from clinically infected patients and nineteen synthesized single/double/multiple amino acid-substituted mutants were tested with commercial ELISA kits. Immunofluorescence staining of transfected cells and Western blot analysis confirmed that these ORFs were expressed at comparable levels in HEK-293 cells. W1S and adr4 were clearly detected, whereas W3S could not be detected. Using the same commercial immunoassay kit, we found that the single mutants, K120P and D123T, were marginally reactive, whereas W3S-aW1S and the double mutant, K120P/D123T, exhibited antigenicity roughly equivalent to the wild-type wako1S. On the other hand, the single mutants of W1S, P120K and T123D, significantly impaired the reactivity, while W1S-aW3S and the double mutant of W1S, P120K/T123D, resulted in a complete loss of antigenicity. In addition, ELISA revealed reduced HBs antigenicity of two mutants, W1S N146G and W1S Q129R/G145R. These commercial ELISA-based antigenic reactivities of HBsAg were also strongly correlated with the predicted Ai alterations of affected amino acids due to the specific mutation. In conclusion, this study showed for the first time that lysine (K120) and aspartate (D123) simultaneously affected HBsAg antigenicity, leading to diagnostic failure. These findings will improve diagnostic assays and vaccine development.

Around 350 million people are living with hepatitis B virus (HBV), which can lead to death due to liver cirrhosis and hepatocellular carcinoma (HCC). Various antiviral drugs/nucleot(s)ide analogues are currently used to reduce or arrest the replication of this virus. However, many studies have reported that nucleot(s)ide analogue-resistant HBV is circulating. Cellular signaling pathways could be one of the targets against the viral replication. Several studies reported that viral proteins interacted with mitochondrial proteins and localized in the mitochondria, the powerhouse of the cell. And a recent study showed that mitochondrial turnover induced by thyroid hormones protected hepatocytes from hepatocarcinogenesis mediated by HBV. Strong downregulation of numerous cellular signaling pathways has also been reported to be accompanied by profound mitochondrial alteration, as confirmed by transcriptome profiling of HBV-specific CD8 T cells from chronic and acute HBV patients. In this review, we summarize the ongoing research into mitochondrial proteins and/or signaling involved with HBV proteins, which will continue to provide insight into the relationship between mitochondria and HBV and ultimately lead to advances in viral pathobiology and mitochondria-targeted antiviral therapy.

Background and aim: Hepatitis B caused by HBV is a serious public health hazard prevalent worldwide including Bangladesh. Few scattered molecular studies of HBV have been reported in Bangladesh. This study aimed to analyze the genetic variability of RT/HBsAg overlapping region of HBV isolates of Bangladesh and determination of correlation among the genotype/serotype and HBsAg escape and/or drug-resistant mutations. Methods: A total of 97 complete HBsAg sequences of Bangladeshi HBV isolates from 2005 to 2017 from NCBI GenBank were extracted and analyzed using several HBV bioinformatics tools such as Geno2pheno-HBV, HBV Serotyper, HIV-Grade:HBV-Tool, and CLC sequence viewer. Results: The prevalence of genotypes A, C, and D are 18, 46 and 35% which correspond to serotype adw, adr, and ayw, respectively. The prevalence of HBsAg escape mutations is 51% and most of which (62%) are found in the genotype D followed by 32% in genotype C and 6% in genotype A. Interestingly most (24/36) of the sequences of HBsAg escape mutations contained 128 V mutant which all belongs to only serotype ayw3 (Genotype D). Prevalence of drug-resistant mutations is ~ 11%, most of which are from genotype C (63.64%) and D (36.36%). Lamivudine resistant mutations were found in ~ 11% of sequences followed by Telbivudine 10% and Adefovir 3% where Tenofovir showed susceptibility to all 97 sequences. Moreover, 7 among of 97 sequences showed both HBsAg and drugs resistant mutations and none of them are found due to the same nucleotide substitutions. Conclusion: There is a strong correlation among the genotype/serotype and HBsAg escape and/or drug-resistant mutations. This meta-analytical review will be helpful for genotype-serotype prediction by PCR-based diagnosis and development of vaccine and/or diagnostic kits, and the treatment against HBV infection in the future.

Long interspersed nuclear element 1 (LINE-1 or L1) is a non-long terminal repeat (LTR) retrotransposon that constitutes approximately 17% of the human genome. Since approximately 100 copies are still competent for retrotransposition to other genomic loci, dysregulated retrotransposition of L1 is considered to be a major risk factor of endogenous mutagenesis in humans. Thus, it is important to find drugs to regulate this process. Although various chemicals are reportedly capable of affecting L1 retrotransposition, it is poorly understood whether phytochemicals modulate L1 retrotransposition. Here, we screened a library of compounds that were derived from phytochemicals for reverse transcriptase (RT) inhibition with an in vitro RT assay. We identified capsaicin as a novel RT inhibitor that also suppressed L1 retrotransposition. The inhibitory effect of capsaicin on L1 retrotransposition was mediated neither through its receptor, nor through its modulation of the L1 promoter and/or antisense promoter activity, excluding the possibility that capsaicin indirectly affected L1 retrotransposition. Collectively, capsaicin suppressed L1 retrotransposition most likely by inhibiting the RT activity of L1 ORF2p, which is the L1-encoded RT responsible for L1 retrotransposition. Given that L1-mediated mutagenesis can cause tumorigenesis, our findings suggest the potential of capsaicin for suppressing cancer development.