中国人群流行的乙型肝炎病毒特异性CTL表位特点分析

Analysis of variation in CTL epitope of HBV popular in China

目的研究中国人群中流行的乙型肝炎病毒(HBV)基因型B型和C型特异性CTL表位的序列特点。方法以国外文献报道的13个HBV的CTL表位氨基酸序列为参考序列,分析其与GenBank下载的45条及作者从乙型肝炎病人血清中扩增的另外5条B型或C型CTL表位氨基酸序列的差别。结果与参考序列相比,本研究分析的B型和C型HBV特异性CTL表位氨基酸序列变异发生频率较高。在本研究分析的13个表位中,变异发生率超过70%的表位在B型HBV有4个,分别是表位FLLTRILTI(A0201,S183-191)、VLQAGFFLL(A0201,S188-196)、ILSPFLPLL(A0201,S382-390)和FLPSDFFPSV(A0201,C18-27),C型HBV有2个,分别是表位ILSPFLPLL(A0201,S382-390)和FLPSDFFPSV(A0201,C18-27)。其中文献中研究最多的HBcAg表位18-27(FLPSDFFPSV),在我国流行的B型和C型HBV中表位的变异率分别高达71%和97%。结论中国人群流行的B型和C型HBV特异性CTL表位与国外文献报道的CTL表位相比在大多数位点上都出现变异,并且不同表位的变异率差异很大,在检测CTL数量和功能时应根据这一特点设计实验。

Objective To analyze the variation in CTL epitope of hepatitis B virus （HBV） popular in China. Methods Amino acid sequences of 13 cytotoxic T lymphocyte （CTL） epitopes previously reported abroad were taken as reference sequences, and comparison was made draw between these reference sequences and both the 45 CTL-epitopic sequences obtained from the Genbank and also 5 CTL-epitopic sequences from native patients with chronic hepatitis B, using Vector NTI software. Results Sequence variations were observed frequently within several CTL eptitopes of HBV genotype B and C compared with the reference sequences. In the 13 analyzed CTL epitopes, 4 showed variation accounting over 70% in genotype B, and 2 have variance over 70% in occurrence in genotype C. Among these, C18-27 （FLPSDFFPSV）, HBcAg-derived CTL epitope which was the most frequently studied previously, is showed in variation more frequently in HBV genotype B and C popular in China, reaching 71% and 97%, respectively. Conlusion Some CTL epitopic sequences of HBV genotype B and C popular in China have their own charactiristic difference from previously reported ones, which should be considered in the study of CTL response of Chinese subjects.