乙型肝炎病毒基因组高变区界定的初步研究

Identification and characterization of high variable regions in hepatitis B virus genome of adr and adw serotypes

目的:探讨乙型肝炎病毒(HBV)基因组是否存在高保守区或高变区,并探讨前-前-S基因和前-X基因的存在方式. 方法:自GenBank中按血清型搜索符合要求的HBV全基因组序列,并应用Vector 6.0版软件进行核苷酸序列同源性的分析和比较. 结果:GenBank中搜索出28个adr血清型和22个adw血清型HBV病毒株全基因组,比较后发现2种血清型的核苷酸序列总一致率分别为76.6%和73.9%;adr血清型病毒株存有高度变异区和高度变异区,一致率分别为54.5%和92.1%;adw血清型基因组内部含有高度保守区,一致率为85.0%,不含有高度变异区.前-前-S区的存在是较为普遍的现象,而前-X区的编码具有adr血清型特异性特点,在某些病毒基因组中,因为存在A2608→C/T、和C/A2733→T替换突变,导致其前-X基因编码区起始密码子突变,因此部分HBV基因组无前-X基因结构区. 结论:HBV基因组内部可能存在高度保守区,前-前-S区的存在是一个重要的现象,而前-X编码区具有adr血清型特异性的特点.

AIM: To identify a hypervariable region or a hyperoonservative region in hepatitis B virus (HBV) genome and to study the pre-X region and the pre-pre-S region. METHODS: Full-length of HBV genomes deposited in GenBank were searched and compared for their identity and homology. According to their sequences, the HBV genomes of adr or adw serotypes were selected. The Vector 6.0 software was used to compare the identity and difference among the strains of HBV genomes. RESULTS: Twenty-eight strains of HBV genome in GenBank belong to adr serotype HBV genome, and 22 strains belong to adw serotype. After being compared, the total identity rates were 76.6% and 73.9%, respectively. There might be a hypervariable region and a hyperconservative region in adr serotype HBV genome, with the regional identity rate of 54.5% and 92.1%, respectively. There might be a hyperconservative region in adw serotype HBV genome, with the regional identity rate of 85.0%. Region coding pre-pre-S gene was popular in the strains. Pre-X region might be a serotype-specific gene. A2608C/T and/or C/A2733T replacement mutation resulted in disability of coding pre-X gene. CONCLUSION: There may be a hyperconservative region in HBV genome. Pre-pre-S gene and pre-X gene are worthy of further study.