人巨细胞病毒UL148A、UL148B、UL148C、UL148D基因在临床株中的多态性研究

Polymorphisms of human cytomegalovirus UL148A, UL148B, UL148C, UL148D genes in clinical strains

目的研究人巨细胞病毒(human cytomegalovirus,HCMV)UL148A、UL148B、UL148C和UL148D基因序列在临床低传代分离株中的多态性。方法对22株经荧光定量PCR方法(Q-PCR)检测HCMV-DNA为阳性的临床株进行HCMV UL148A、UL148B、UL148C和UL148D基因全序列PCR扩增,并对PCR扩增产物进行序列测定及分析。结果22株临床株序列与Merlin株相比.临床分离株UL148A基因的核苷酸变异率为0.5%～8.3%,氨基酸变异率为1.3%～6.3%;UL148B基因核苷酸变异率为0.5%～4.6%,氨基酸变异率为1.3%～5.0%;UL148C基因核苷酸变异率为0.5%～3.0%,氨基酸变异率为1.3%～3.9%;UL148D基因核苷酸变异率为0.6%～8.5%,氨基酸变异率为1.7%～8.1%。22株HCMV UL148A和UL148D序列均分为3个型。与Merlin株比较,除U96株外,来自未经传代的尿标本中的UL148A、UL148B、UL148C和UL148D基因编码产物含有的翻译后修饰位点均保守。结论UL148C基因无论在核苷酸序列还是在蛋白的氨基酸结构上均较为保守。统计学分析显示HCMV UL148A和UL148D基因呈现一定的相关性。

Objective To describe the features of HCMV UL148A, UL148B, UL148C and UL148D open reading frames （ORF） and the variable sites within the frames in clinical strains. Methods PCR was performed to amplify these ORFs in 22 clinical strains. PCR amplification products were sequenced directly and analyzed. Results The nucleotide diversity of UL148A, UL148B, UL148C and UL148D ORFs in studied strains is 0.5% to 8.3%, 0.5% to 4.6%, 0.5% to 3.0% and 0.6% to 8.5%, respectively; the amino acid diversity of their putative proteins is 1.3% to 6.3%, 1.3% to 5.0%, 1.3% to 3.9% and 1.7% to 8.1%, respectively, compared to the Merlin strain. The modification sites of UL148A, UL148B, UL148C and UL148D predicted proteins from strains in unpassaged urine samples were conserved, except for strain U96, compared with that of the Merlin strain. By phylogenetic and statistical analysis, the UL148A and UL148D sequences of clinical strains were classified into three groups. Conclusion Compared to the UL148A, UL148B and UL148D ORFs, the UL148C ORF was relatively conserved, as well as the amino acid sequence of the UL148C putative protein. Isolates that have been passaged several times in human embryonic lung fibroblasts showed some changes of modification sites, however. A discrete linkage was found between the groups of UL148A gene and those of UL148D gene.