Alestig E, Hannoun C, Horal P, Lindh M
Department of Clinical Virology, Göteborg University, Göteborg, Sweden.
J Clin Microbiol. 2001 Sep;39(9):3200-3. doi: 10.1128/JCM.39.9.3200-3203.2001.
Mutations that prevent the expression of the hepatitis B e antigen frequently emerge in the immunoreactive phase of infection. The predominant mutation, the precore G-->A-1896 mutation, is restricted by the variability at position 1858 and is rare in strains with cytosine at nucleotide 1858. The C-1858 variant is characteristic of genotype A. It also occurs in genotypes C and F, but not in B, D, or E, explaining the geographical variation in the prevalence of precore mutants. C-1858 strains have been frequently observed in southeast Asia, but have not been phylogenetically characterized. By sequencing eight complete hepatitis B virus genomes, C-1858 variants of east Asian origin were found to constitute a phylogenetic entity within genotype C that probably diverged several hundred years ago. Further study of the distribution of this variant is warranted.
在感染的免疫反应期，经常会出现阻止乙肝e抗原表达的突变。主要的突变，即前核心区G→A-1896突变，受1858位核苷酸变异的限制，在1858位核苷酸为胞嘧啶的毒株中很少见。1858位胞嘧啶变异体是A型基因型的特征。它也出现在C型和F型基因型中，但不出现在B型、D型或E型基因型中，这解释了前核心区突变体流行率的地理差异。在东南亚经常观察到1858位胞嘧啶毒株，但尚未对其进行系统发育特征分析。通过对8个完整的乙肝病毒基因组进行测序，发现东亚起源的1858位胞嘧啶变异体在C型基因型中构成一个系统发育实体，可能在几百年前就已分化。有必要对该变异体的分布进行进一步研究。
