广州地区HCMV低传代临床病毒株UL143基因的多态性研究

目的研究广州地区人巨细胞病毒（HCMV）临床低传代分离株UL143基因的多态性。方法对3株经多重PCR鉴定的HCMV临床低传代分离株进行HCMV UL143基因全序列扩增，扩增产物克隆到pMD18-T载体上测序，并将其序列与GenBank中公布的其它临床分离株UL143基因一起进行分析。结果D3株UL143基因因碱基缺失形成多处终止密码无法产生有功能的蛋白；Toledo株UL143基因开放读码框由279个核苷酸组成．编码蛋白由92个氨基酸残基组成：其它临床分离株UL143基因开放读码框均由252个核苷酸组成。DNA序列比较保守，变异均为碱基替换。编码蛋白由83个氨基酸残基组成，氨基酸序列也很保守，不同临床分离株氨基酸变异率为1．2％-2．4％：HCMV UL143蛋白翻译后修饰位点在除Toledo株之外的所有分离株中均高度保守．没有缺失或新增；不同临床分离株UL143蛋白二级结构有所不同；除Toledo株外，其余分离株UL143蛋白的等电点均为8．75。结论临床低传代分离株HCMV UL143基因DNA及其编码产物的氨基酸序列极为保守。但仍存在一定多态性。

Human Cytomegalovirus UL143 Gene Polymorphisms in Low-Passage Clinical Isolates in Guangzhou

Objective To investigate the polymorphism of human cytomegalovirus UL143 gene of low passage clinical isolates in Guangzhou, China. Method PCR was performed to amplify the entire HCMV UL143 gene region of 3 clinical isolates, which had been proven by multiplex PCR. The amplification products were cloned into pMD18- T-Vector and subjected to sequencing. The result of DNA sequences were analyzed together with the one of published homologous sequences in GenBank from 14 clinical isolates. Result There were several stop codons in UL143 gene due to a base deletion in open reading frame （ORF） of D3 isolate, which could lead to produce non-functional protein. UL143 ORF of Toledo isolate consisted of 279 nucleotides, encoding a protein with 92 amino acids. UL143 ORFs of other isolates consisted of 252 nucleotides, encoding a protein with 83 amino acids. The DNA sequences were quite conserved and all the variations were base substitution. The amino acid sequences of different isolates were highly conserved, with variation of 1.2%-2.4%. There were no additional or deleted sites of post translational modification of UL143 protein in all clinical isolates except Toledo isolate. There were some differences in the secondary structure among different isolates. The isoelectric point of UL143 protein of all clinical isolates except Toledo isolate was 8.75. Conclusion All DNA and deduced amino acid sequences of UL143 gene shared great similarity among HCMV clinical strains regardless of their polymorphism.