引起新生儿晚期黄疸的巨细胞病毒UL144基因多态性研究

Genetic variations in the UL144 genes of human cytomegalovirus strains collected from late jaundice infants

【目的】研究引起新生儿晚期黄疸的人巨细胞病毒（cytomega lovirus,HCMV）UL144基因的多态性,探讨HCMV UL144基因多态性与致病性之间的关系。【方法】应用荧光定量PCR法检测本院新生儿科2008年1—12月98例晚期黄疸新生儿样本HCMV-DNA含量,采用巢式聚合酶链反应扩增阳性标本HCMV UL144基因开放读码框（ORF）,结果进行双向DNA测序,通过BioEdit、DNAstar、GeneDoc等软件进行序列分析。【结果】1）30例晚期黄疸新生儿HCMV荧光定量PCR检测阳性,阳性率30.6%,其中2例UL144基因扩增阴性。2）28株UL144基因与Toledo株进行同源性比较,核苷酸水平为80.4%~99.2%,氨基酸水平为78.9%~98.8%。种系进化树分析将DNA序列分为3个基因型,其中G1型7株（25%）,G2型7株（25%）,G3型14株（50%）。3）ExPASy数据库预测分析UL144基因编码产物重要功能区包括2个半胱氨酸富集结构域（CRD1、CRD2）、1个跨膜区和1个胞浆区。G1-G3型蛋白质二级结构高变区主要分布在CRD1区,跨膜区和胞浆区结构高度保守。【结论】1）HCMV感染是导致新生儿晚期黄疸的原因之一;2）HCMV UL144基因编码跨膜区和胞浆区结构高度保守,CRD1呈高度多态性;3）晚期黄疸新生儿中HCMV感染以G3型为主。

【Objective】 To investigate the genetic variations of cytomegalovirus UL144 gene in clinical strains and to explore the relationship between the UL144 genotype and specimens in late jaundice cases. 【Methods】 PCR was performed to amplify the entire HCMV-UL144 gene region of clinical strains,which had been proven containing detectable HCMV-DNA by FQ-PCR.The PCR products were sequenced and phylogenetic analysis was conducted using BioEdit,DNAstar,GeneDoc. 【Results】 1） 30 infants with late jaundice were HCMV infection,the positive rate was 30.6 %;2） Alignment comparison of clinical strains UL144 sequences with Toledo disclosed nucleic acid variability rate 80.4% to 99.2%.The UL144 sequence distributed among three genotypes,Group1（25%）,Group2（25%）,and Group3（50%）respectively.3） The UL144 protein consists of two cysteine-rich domains（CRD）,one transmembrane domain,and one cytoplasmic domain（cyto）.There was a high level of conservation in the transmembrane and cytoplasmic domains of UL144 between the different isolates while was slightly more variable in CRD1. 【Conclusions】 1）HCMV infection may be etiologically associated with late jaundice in some infants.2） Although the genomic sequence of UL144 are generally well conserved in the transmembrane and cytoplasmic domains,a certain number of genes exhibit a high degree of inter-strain variation in CRD1.3）The group 3 genotype is more prevalent in the late jaundice cases than other genotype.