title: Comparative analysis of CpG islands among HBV genotypes.
abstract: DNA methylation is being increasingly recognized to play a role in regulation of hepatitis B virus (HBV) gene expression. The aim of this study was to compare the CpG island distribution among different HBV genotypes. We analyzed 176 full-length HBV genomic sequences obtained from the GenBank database, belonging to genotypes A through J, to identify the CpG islands in the HBV genomes. Our results showed that while 79 out of 176 sequences contained three conventional CpG islands (I-III) as previously described, 83 HBV sequences harbored only two of the three known islands. Novel CpG islands were identified in the remaining 14 HBV isolates and named as CpG island IV, V, and VI. Among the eight known HBV genotypes and two putative genotypes, while HBV genomes containing three CpG islands were predominant in genotypes A, B, D, E, and I; genotypes C, F, G, and H tended to contain only two CpG islands (II and III). In conclusion, the CpG islands, which are potential targets for DNA methylation mediated by the host functions, differ among HBV genotypes, and these genotype-specific differences in CpG island distribution could provide new insights into the understanding of epigenetic regulation of HBV gene expression and hepatitis B disease outcome.
authors: Department of Infectious Diseases, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
authors: Yongmei
authors: Y
authors: Zhang
authors: Chenxiao
authors: C
authors: Li
authors: Yijun
authors: Y
authors: Zhang
authors: Haoxiang
authors: H
authors: Zhu
authors: Yaoyue
authors: Y
authors: Kang
authors: Hongyan
authors: H
authors: Liu
authors: Jinyu
authors: J
authors: Wang
authors: Yanli
authors: Y
authors: Qin
authors: Richeng
authors: R
authors: Mao
authors: Yi
authors: Y
authors: Xie
authors: Yuxian
authors: Y
authors: Huang
authors: Jiming
authors: J
authors: Zhang
mesh_terms: D018899:CpG Islands / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics; D016679:Genome, Viral / Q000235:genetics*; D005838:Genotype; D006515:Hepatitis B virus / Q000235:genetics*