A73基因的克隆及其编码区序列分析

目的 克隆Epstein-Barr（EB）病毒A73基因，并分析其编码区序列变异情况，为进一步研究其生物学功能提供基础。方法 从7例鼻咽癌组织中分别提取其总RNA，以RT-PCR扩增A73基因编码序列，将其克隆入pGEM-T-Easy载体进行测序，以Blast软件在Genbank数据库中对其进行序列分析。结果 成功克隆了高发区鼻咽癌的A73基因，序列分析表明该基因编码序列第45nt发生A→C的碱基替换，该变异位于第VB外显子的157154nt，未引起相应第15位氨基酸的替换（CCA→CCC，P→P），其变异频率为7／7。结论 高发区鼻咽癌EB病毒A73基因的编码序列存在变异，该变异属于鼻咽癌相关的多态性，有可能参与EB病毒某亚型的构成。

Cloning of A73 gene and its coding sequence analysis

OBJECTIVE: To clone A73 gene of Epstein-Barr virus (EBV) and examine the variation of its coding sequence. METHODS: A73 coding sequence (CDS) amplified from 7 patients in nasophryngeal carcinoma (NPC) biopsies by RT-PCR was cloned into pGEM-T-Easy vector to construct the recombinant plasmid, which was subjected to sequence analysis in Gen Bank database using Blast software. RESULTS: A73 gene from nasophryngeal carcinoma was successfully cloned into pGEM-T Easy vector. A locus with conversion of A-->C in A73 was found at CDS 45 nt, located in the exonVB157154 nt, which did not result in an amino acid replacement, and the variation frequency was 7/7. CONCLUSION: There is a point mutation in A73 CDS of EBV isolated from NPC tissue, which might produce NPC-associated polymorphism with possible involvement in the composition of some subtype of EB virus.