Monozygotic twins share identical genomic DNA and are indistinguishable using conventional genetic markers. Increasing evidence indicates that monozygotic twins are epigenetically distinct, suggesting that a comparison between DNA methylation patterns might be useful to approach this forensic problem. However, the extent of epigenetic discordance between healthy adult monozygotic twins and the ...

CONTEXT Hepatitis B and Hepatitis C (HBV and HCV) infections are both major causes of hepatocellular carcinoma (HCC). However, HCC caused by each of these two viruses has unique characteristics that should be studied independently to that of another one. While HBV- and HCV-related HCCs share similar host and environmental risk factors such as male gender, age above 50 years old, family history ...

Genetic polymorphisms can shape the global landscape of DNA methylation, by either changing substrates for DNA methyltransferases or altering the DNA binding affinity of cis-regulatory proteins. The interactions between CpG methylation and genetic polymorphisms have been previously investigated by methylation quantitative trait loci (mQTL) and allele-specific methylation (ASM) analysis. However...

Hepatitis B viruses (HBV) and related viruses, classified in the Hepadnaviridae family, are found in a wide variety of mammals and birds. Although the chimpanzee has been the primary experimental model of HBV infection, this species has not been considered a natural host for the virus. Retrospective analysis of 13 predominantly wild-caught chimpanzees with chronic HBV infection identified a uni...

The rate of HBV DNA integration into the genome of hepatocellular carcinoma (HCC) cells varies greatly among HCC tissues from different geographical districts. Because of the potential etiological significance of identifying HBV DNA integration in HCC tissues from Korea, we investigated 13 aseptically obtained HCC surgical specimens by Southern blot analysis. Among 13 HCCs, eight (61.5%) contai...

The majority of hepatitis B virus (HBV) transcripts are not normally spliced during the viral life cycle, but several splice donor and acceptor sites are conserved on HBV transcripts. In particular, the genome region between nt 450 and 500 of the HBV genome appears to be rich in such sequences. In this study we deleted a short 30-nt sequence between a conserved splice donor site at HBV genome p...

Cytosine methylation promotes deamination. In eukaryotes, CpG methylation is thought to account for CpG underrepresentation. Whether scarcity of CpGs in prokaryotic genomes is diagnostic for methylation is not clear. Here, we report that Mycoplasms tend to be CpG depleted and to harbor a family of constitutively expressed or phase variable CpG-specific DNA methyltransferases. The very CpG poor ...

Advances in sequencing technology allow researchers to map genome-wide changes in DNA methylation in development and disease. However, there is a lack of experimental tools to site-specifically manipulate DNA methylation to discern the functional consequences. We developed a CRISPR/Cas9 DNA methyltransferase 3A (DNMT3A) fusion to induce DNA methylation at specific loci in the genome. We induced...

The hepatitis B virus (HBV) belongs to the hepadnavirus family. The genome of the virus, formed by a small DNA molecule with 3,200 base pairs, has 4 strongly overlapping protein coding regions: ORF preS/S, corresponding to the envelope proteins that constitute the HBV surface antigen (HBsAg); ORF preC/C, which encodes the viral capsid component (core antigen or HBcAg) and a non-structural prote...

The core promoter of hepatitis B virus (HBV) is crucial in viral replication. Our previous investigation in clinical serum samples indicated that deletions in the viral core promoter (from nucleotide 1758 to 1777 and 1749 to 1768 respectively) may lead to increase in viral replication. We propose to characterize these deletion mutants in a cell-based system that supports HBV replication. Replic...