Luo Kangxian, Liu Zhihua, He Haitang, Peng Jie, Liang Weifang, Dai Wei, Hou Jinlin
Department of Infectious Diseases, Nanfang Hospital, Guangzhou 510515, China.
Virus Genes. 2004 Aug;29(1):31-41. doi: 10.1023/B:VIRU.0000032787.77837.09.
Among hepatitis B virus (HBV) genotypes the B and C are most prevalent in China. To further study on the inside story of the intertypes, the genotype of 136 sequences from Chinese patients were analyzed either by restriction fragment length polymorphism on fragments or by phylogenetic analysis and bootscanning on full genome. The 22 complete sequences of genotype B clustered with different genotypes depending on gene fragments analyzed, which indicated that recombinant events occurred during HBV evolutionary history. To locate the recombinant regions, the sequences of HBV entire genome were analyzed by SimPlot program. The recombinant regions of B genotype with recombination were mapped in the pre-C/C region with relatively less varied size. Besides, three sequences of genotype C have recombination with genotype B or D in different regions. However, among all of the 136 sequences, none of authentic genotype B was identified. To investigate the possible mechanism responsible for intertype recombination, the selection pressure on the recombinant region was estimated by using CODEML program. All models allow for positively selected sites suggest existence of positive selection pressure. In conclusion, the genotype B with recombination was exclusive subgroup of genotype B in China. The mosaic genotype B might result from immune pressure on the pre-C/C gene.
在乙型肝炎病毒（HBV）基因型中，B型和C型在中国最为普遍。为了进一步研究不同基因型之间的内在关系，对来自中国患者的136个序列的基因型进行了分析，分析方法包括对片段进行限制性片段长度多态性分析，以及对全基因组进行系统发育分析和靴带扫描。根据所分析的基因片段，22个B基因型的完整序列与不同的基因型聚类，这表明在HBV进化历史中发生了重组事件。为了定位重组区域，使用SimPlot程序对HBV全基因组序列进行了分析。发生重组的B基因型的重组区域定位在前C/C区域，其大小变化相对较小。此外，3个C基因型序列在不同区域与B型或D型发生了重组。然而，在所有136个序列中，未鉴定出真正的B基因型。为了研究基因型间重组的可能机制，使用CODEML程序估计了重组区域的选择压力。所有允许存在正选择位点的模型都表明存在正选择压力。总之，发生重组的B基因型是中国B基因型的一个独特亚组。镶嵌型B基因型可能是由前C/C基因上的免疫压力导致的。
