人巨细胞病毒临床分离株UL131A-128mRNA转录方式的研究

目的 研究人巨细胞病毒（ human cytomegalovirns,HCMV） UL131 A-128序列在临床低传代分离株中的转录方式.方法 用3＇RACE技术扩增HCMV不同临床株,不同时期的UL131A,UL128,UL130的mRNAs并测序分析;利用PCR技术在HCMV临床株cDNA文库中筛选分别含有UL13IA,UL130,UL128序列的阳性克隆,测序并分析结果.结果 成功在临床低传代分离株中得到UL13IA,UL128,UL130基因的转录结构,UL131A,UL130的转录方式和文献报道一致,UL131A含有两个外显子,UL130为此区域内唯一不含内含子的基因.而UL128基因的转录本呈现了两种转录方式,一种结构包含三个外显子,长度为519 bp;而另一种结构包含三个外显子和第一内含子结构,长度为642 bp,在不同病毒株的不同时期均显示了包含第一内含子结构转录本的含量明显高于仅有外显子结构的UL128转录本的含量.UL131A-128三个基因在病毒的即刻早期,早期,晚期均存在.3＇RACE得到结果与HCMV cDNA文库筛选得到的结果相一致.结论 UL131A,UL130和UL128基因的mRNA结构的起始位点不同,但他们在3’末端拥有共同的终止位点.HCMV临床株UL 131A-128基因转录方式的复杂结构可能在HCMV感染的不同时期具有重要作用.     

Role of human cytomegalovirus genotype polymorphisms in AIDS patients with cytomegalovirus retinitis

Although several host factors have been identified to influence the course of HCMV infection, it still remains unclear why in AIDS patients without highly active antiretroviral therapy human cytomegalovirus (HCMV) retinitis is one of the most common opportunistic infections, whereas in other immunosuppressed individuals it has a low incidence. It was suggested that HCMV glycoprotein B strains may be suitable as marker for virulence and HCMV retinitis. Moreover, UL144 ORF, a member of the TNF-α receptor superfamily, may play a crucial role in innate defences and adaptive immune response of HCMV infection. Furthermore, sequence analyses of HCMV genes UL128, UL130, and UL131A as major determinants of virus entry and replication in epithelial and other cell types were performed. To evaluate the association of sequence variability of depicted viral genes with HCMV retinitis and in vitro growth properties in retinal pigment epithelial cells (RPE) and human foreskin fibroblasts (HFF), we compared 14 HCMV isolates obtained from vitreous fluid and urine of AIDS patients with clinically proven HCMV retinitis. Isolates were analyzed by PCR cycle sequencing and phylogenetic analysis. In addition, sequences of HCMV strains AF1, U8, U11, VR1814, and its cell culture adapted derivates were included. Sequence analysis of gB yielded three genetic subtypes (gB type 1 (5 isolates), gB type 2 (12 isolates), and gB type 3 (5 Isolates)), whereas sequence analysis of UL144 showed a greater diversity (7 isolates type 1A, 2 isolates type 1C, 7 isolates type 2, and 3 isolates type 3). In contrast, the UL128, UL130, and UL131A genes of all low-passage isolates were highly conserved and showed no preferential clustering. Moreover, in HFF and RPE cells, all of our HCMV isolates replicated efficiently independently of their genetic subtype. In conclusion, beside a possible link between the gB subtype 2 and HCMV retinitis, our study found no direct evidence for a connection between UL144/UL128/UL130/UL131A genotypes and the incidence of HCMV retinitis in AIDS patients.     

UL74 of human cytomegalovirus reduces the inhibitory effect of gH-specific and gB-specific antibodies

The human cytomegalovirus (HCMV) glycoproteins gH (UL75) and gL (UL115) can form complexes with gO (UL74) or with proteins of the UL128-UL131A locus. Deletion of gO abolishes cell-free virus transmission and renders cell-associated virus transmission in fibroblasts more sensitive to inhibition by human anti-HCMV serum. To test whether the latter effect is specific for gO, we compared mutants with deletions in UL74, UL99 and the UL128-131A locus regarding their sensitivity to anti-HCMV antibodies. UL74 deletion mutants were more sensitive to a further restriction by polyspecific or gH-specific antibodies than control mutants, showing that gO specifically protects focal growth against inhibitory antibodies. This effect was not confined to gH-specific antibodies, as UL74 deletion mutants were also inhibited by an anti-gB antibody. In conclusion, gO specifically promotes focal spread in the presence of gH and gB antibodies, thus contributing to the ability of HCMV to resist the host’s immune response.     

人类巨细胞病毒UL144基因在临床低传代分离株中的多态性研究

目的：探讨人类巨细胞病毒（human cytomegalovirus,HCMV)UL144序列在临床患儿低传代分离株中的多态性及其与临床疾病的关系。方法：对65株HCMV临床低传代分离及7例同年龄组HCMV－DNA定量PCR方法检测阳性健康儿尿液进行HCMV-UL144 PCR扩增分析，对HCMV-UL144扩增阳性标本进行HMA－SSCP分析，并对其中32个阳性标本进行HCMV-UL144基因全序列测定及分析。结果：65株分离株中有55株UL144全序列引物PCR扩增为阳性，7份QPCR检测HCMV-DNA阳性健康儿尿液中5份UL144全序列PCR扩增为阳性，60份UL144扩增阳性标本HMA－SSCP（heteroduplex mobility assay and single-stranded conformation polymorphism)分析呈现3种典型带形，32例个测序标本序列呈现较高的多态性，差异多位于序列的前半部，种系发生图谱分析可大致分为3组，二级结构预测表现为6种类型，在重要的蛋白质功能的序列分布以Ⅰ型为主，黄患儿以Ⅲ型为主。32个HCMV-UL144序列已被GenBank收录，结论:HCMV-UL144广泛存在于临床低传代分离株中，序列呈序高度多态性，不同疾病类型的HCMV-UL144序列不同，提示UL144基因可能在HCMV致病上起一定的作用。     

Ganciclovir resistance mutations in UL97 and UL54 genes of Human cytomegalovirus isolates resistant to ganciclovir

Human cytomegalovirus (HCMV) resistance to ganciclovir results from mutations in viral phosphotransferase (UL97) and/or DNA polymerase (UL54) genes. The HCMV isolates from the blood of immunocompromised patients with persisting presence of the pp65 antigen in the blood in spite of ganciclovir therapy were tested for ganciclovir susceptibility by an immediate-early antigen plaque reduction assay, and the UL54 and UL97 genes were sequenced. Nine isolates from eight patients (six patients with acquired immune deficiency syndrome (AIDS), one liver transplant recipient and one renal transplant recipient) showed phenotypic resistance to ganciclovir. All these ganciclovir-resistant HCMV isolates harbored one or more of the following UL97 mutations: M460V, A594V, A594T, L595S, C603W, and M615V. Two isolates harbored the P522S mutation in the UL54 gene. The M615V mutation in the UL97 gene has not been reported earlier and its role in ganciclovir resistance remains to be elucidated. In ganciclovir-resistant HCMV isolates the UL54 gene was less frequently mutated than the UL97 gene. The P522S mutation was relatively frequent in UL54-mutated HCMV isolates.     

Polymorphisms within human cytomegalovirus chemokine (UL146/UL147) and cytokine receptor genes (UL144) are not predictive of sequelae in congenitally infected children

Human cytomegalovirus (HCMV) viral chemokine, UL146, and TNF alpha-like receptor UL144 genes show a high degree of hypervariability in clinical isolates. These proteins are predicted to be immune modulators and may contribute to the pathogenesis of HCMV infections. We analyzed the UL146 and UL144 genetic variation of 51 HCMV isolates from congenitally infected children and 13 isolates from children in childcare. There was no statistically significant correlation between UL146 and UL144 genotypes and HCMV disease and/or sequelae. However, there were some groups that had a relatively large proportion of asymptomatic outcomes. These included UL146 group 8 (7/8 asymptomatic) and UL146 group 10 (3/3 asymptomatic). UL144 group B had 11/15 (73%) asymptomatic. UL146 and UL144 genes remained stable in serial isolates from children in daycare for intervals up to three years. These results indicate that most UL146 and UL144 genotypes do not predict clinical sequelae following congenital HCMV infections.     

与人巨细胞病毒UL128两种不同结构蛋白相互作用蛋白的筛选与分析

目的 利用酵母双杂交系统从人胎脑cDNA文库中筛选与两种不同转录结构的人巨细胞病毒(HCMV)UL128编码蛋白相互作用的蛋白,比较两者相互作用蛋白之间的异同点.方法 通过3'RACE和5'RACE技术扩增出两种HCMV UL128片段,其大小分别为519 bp和642 bp,并将其成功构建到酵母诱饵表达载体pGBKT7中.将以上两种酵母表达载体分别转化到酵母菌AH109中,再将文库DNA转化到已含有酵母表达载体的AH109中,筛选与两种片段大小不同的UL128编码蛋白相互作用的人胎脑蛋白,并对筛选得到的阳性克隆进行测序和生物信息学分析.结果 筛出EFEMP2与UL128-519 bp编码蛋白相互作用,THY-1与UL128-642 bp编码蛋白相互作用.结论 成功构建pGBKT7 UL128-519 bp和pGBKT7 UL128-642 bp,并应用酵母双杂交系统分别筛选出EFEMP2和THY-1与UL128-519 bp和UL128-642 bp编码蛋白相互作用,在所筛选得到的相互作用蛋白之间未发现有相同的蛋白,UL128-519 bp和UL128-642 bp所编码的蛋白在HCMV感染致病过程中可能发挥不同的作用.     

Human cytomegalovirus tropism for endothelial/epithelial cells: scientific background and clinical implications

Human cytomegalovirus (HCMV) has been routinely isolated from and propagated in vitro in human embryonic lung fibroblast (HELF) cell cultures, while in vivo it is known to infect predominantly endothelial and epithelial cells. In recent years, genetic determinants of the HCMV tropism for endothelial/epithelial cells were identified in the UL131A/UL130/UL128 locus of HCMV genome of wild‐type strains. UL131A‐UL128 gene products form a complex with glycoprotein H (gH) and L (gL) resulting in a gH/gL/UL131A‐UL128 complex that is required for HCMV entry into endothelial/epithelial cells. In contrast, virus entry into fibroblasts has its genetic determinants in the complex gH/gL/gO (or gH/gL). During primary HCMV infection, the neutralising antibody response measured in endothelial cells (EC) is potent, occurs very early and is directed mostly against combinations of two or three gene products of the UL131A‐128 locus. On the contrary, neutralising antibodies measured in fibroblasts appear late, are relatively weak in potency and are directed against gH and gB. The T‐cell immune response to UL131A‐UL128 gene products remains to be investigated. Recently, a role has been proposed for neutralising antibody in conferring prevention/protection against HCMV infection/disease in pregnant women with primary HCMV infection. However, the level of cooperation between humoral immunity and the well‐established T‐cell protection remains to be defined. Copyright © 2010 John Wiley & Sons, Ltd.     

Recombinant HCMV UL128 expression and functional identification of PBMC-attracting activity in vitro

Human cytomegalovirus (HCMV) has evolved several immune evasion strategies. One strategy is controlling the movement of peripheral blood mononuclear cells (PBMCs) by encoding homologues of chemokines. Our aim was to determine whether HCMV open reading frame (ORF) UL128 could encode a protein that attracts PBMCs like a β-chemokine. The recombinant UL128 protein was synthesized by construction of a stably transfected CHO-UL128 cell line, and a chemotaxis assay showed that UL128 was able to attract PBMCs with a potency equal to that of MIP-1α in vitro. We hypothesize that UL128 protein may act as a β-chemokine homologue in viral pathogenesis.     

Human cytomegalovirus a sequence and UL144 variability in strains from infected children

Human cytomegalovirus (HCMV) displays genetic polymorphisms. This variability may contribute to strain-specific tissue tropism and disease expression in HCMV-infected humans. To determine strain variability in a sequence and UL144 gene regions, 51 low-passage isolates from 44 HCMV-infected children were studied. Isolates were obtained from 28 healthy children attending child care centers in Iowa and from 16 congenitally infected infants born in Texas. Isolates demonstrated substantial nucleotide variation in each gene region. Phylogenetic analysis of a sequence variability allowed 39 isolates to be grouped into six clades. The largest clade contained 16 isolates with > or = 95% nucleotide homology. Forty-eight of the 49 HCMV isolates yielding UL144 amplicons was grouped according to the clades described a few years ago [Lurain et al. (1999) Journal of Virology 73:10040-10050]. No linkage was observed among a sequence, UL144, and glycoprotein B (gB; UL55) polymorphisms. Four Texas and 11 Iowa isolates displayed > or = 95% sequence homology for a sequence and UL144 regions and possessed identical gB genotypes. No relationship between UL144 polymorphisms and outcome of congenital HCMV infection was observed. These data indicate that HCMV strains circulating among young children have UL144 polymorphisms similar to those of HCMV strains excreted by immunocompromised adults. Identification of conserved nucleotide sequences among Iowa and Texas children suggests genetic stability and biologic importance of these gene regions.     

人巨细胞病毒UL149基因在临床低传代分离株中的多态性研究

目的研究人巨细胞病毒(humancytomegalovirus,HCMV)UL149序列在临床低传代分离株中的多态性,探讨HCMV基因多态性与其感染引起不同临床症状之间的关系。方法对29株经荧光定量PCR方法(QPCR)检测HCMVDNA为阳性的临床低传代分离株的细胞培养上清液进行HCMVUL149全序列PCR扩增,并对PCR扩增产物进行序列测定及分析。结果29株临床低传代分离株有26株PCR扩增阳性,与HCMVToledo株进行序列比较分析,26株临床分离株UL149开放阅读框架(openreadingframe,ORF)之间存在着高度的多态性,种系进化树分析结果显示26个序列可分为3个型,黄疸患儿分布以G1型为主;小头畸形以G3型为主;巨结肠仅见于G1、G2型,G3型未见。部分临床分离株存在CKP位点的缺失及TKP位点增加。结论HCMVUL149基因在临床分离株中存在着高度的多态性。来自不同临床症状分离株的UL149基因及其编码蛋白具有一定的结构特点,并与基因型呈一定的相关性。     

Structure and variability of the UL149 open reading frame from low-passage clinical isolates of human cytomegalovirus

Human cytomegalovirus (HCMV), a ubiquitous herpesvirus, causes a lifelong subclinical infection in healthy adults but leads to significant morbidity and mortality in neonates and immunocompromised individuals. A region (referred to as UL/b') present in the Toledo strain of HCMV and low passage clinical isolates contains 19 additional genes, which are absent in the highly passage laboratory strain AD169. One of these genes, UL149 open reading frame, was amplified by PCR and sequenced from isolates obtained from infants with congenital HCMV infection, to determine whether genetic variation of this gene could influence the signs of the virus infection. The major finding is that the UL149 is a variable gene in all 26 clinical isolates, and the sequences from clinical isolates were classified into three major groups. It is concluded that the HCMV UL149 sequence is variable at the nucleotide level and it might play an important role in HCMV infection.     

HMA-SSCP方法研究人类巨细胞病毒UL144基因在临床低传代分离株中的多态性

目的 探讨人类巨细胞病毒（HCMV）UL144序列在临床患儿低传代分离株中的多态性及与临床疾病的关系。方法 对65株HCMV临床低传代分离株及7例同年龄组HCMV，DNA定量PCR方法检测阳性无症状感染儿尿液进行HCMV-ULl44 PCR扩增及HMA-SSCP分析，并对其中32份阳性标本进行测序。结果 65株分离株中有55株UL144全序列引物PCR扩增阳性，7份QPCR检测HCMV—DNA阳性无症状感染儿尿液中5份UL144全序列引物PCR扩增阳性。60份UL144扩增阳性标本HMA-SSCP（异源双链泳动及单链构象多态分析）呈现3种典型带形，巨结肠患儿分离株序列、小头畸形患儿的序列分布以1型为主，巨结肠患儿分离株序列没有2型，黄疽患儿以3型为主。结论 HCMV-UL144广泛存在于临床低传代分离株中，用HMA-SSCP检测HCMV-UL144基因在临床低传代分离株中的多态性是一种可行的方法。HCMV不同疾病类型的HCMV-UL144序列不同，提示UL144基因可能对HCMV致病性起一定作用。     

广州地区人巨细胞病毒临床低传代株UL136基因的序列特征及多态性

目的 研究广州地区新生儿感染人巨细胞病毒(HCMV)临床低传代株UL136基因的序列特征与基因多态性.方法 从10例广州感染新生儿体内分离获得2株(D2、D3)临床HCMV分离株,经多重PCR鉴定后进行UL136基因全序列扩增.PCR产物纯化后进行基因克隆,构建HCMV UL136-pMD18-T重组质粒.经基因测序及应用生物信息学分析方法 ,分析其核酸序列稳定性、编码蛋白质的二级结构与特征.结果 成功分离2株HCMV临床分离株,测序结果 显示,D2、D3及与GenBank中公布的11株临床分离株(4J、51C、39J、33J、63J、22M、10J、32C、29C、27C、Toledo)中,UL136序列高度保守.同源性分析显示在UL136全基因序列1019个核苷酸中,存在30个位点变异,所有的变异均为碱基替换,无插入及缺失突变.编码蛋白的氨基酸序列也高度保守,240个氨基酸残基中,不同临床分离株氨基酸变异率为1.6%～3.7%.不同分离株的UL136蛋白中参与形成二级结构的氨基酸数目及等电点不同.进化树分析结果 显示D2和D3均属于1a群.结论 广州地区临床低传代分离株HCMV UL136基因核苷酸序列及其氨基酸序列极为保守,但仍存在一定多态性.其基因的稳定性提示HCMV UL136开放阅读框(ORF)可能是一个具有重要功能的基因.其编码后修饰位点提示UL136可能与膜受体介导的细胞信号转导通路有关.     

Distribution of UL144, US28 and UL55 genotypes in Polish newborns with congenital cytomegalovirus infections

Human cytomegalovirus (HCMV) is the most common congenital infection. HCMV strains display genetic variability in different regions. Distribution of HCMV genotypes in the population of congenitally infected newborns from Central Poland and viral load in newborns' blood is described and discussed. HCMV isolates were analysed by sequencing at three sites on the genome: the UL144 tumour necrosis factor-alpha (TNFα)-like receptor gene, the US28 beta-chemokine receptor gene and the UL55 envelope glycoprotein B (gB) gene. The newborns' blood was examined for HCMV DNA with a nested (UL144, UL55) or heminested (US28) polymerase chain reaction, and the genotypes were determined by sequence analysis. HCMV DNA was detectable in 25 out of 55 examined newborns born by HCMV-infected mothers (45.5%). The blood viral load in mother-infant pairs was determined. Most of the newborns had identical virus genotype, gB2 (96%), UL144 B1 (88%) and US28 A2 (84%). These genotypes were detected in all newborns with asymptomatic congenital infection. The occurrence of UL144 B1 or US28 A2 genotypes in the babies examined was significant in comparison to other genotypes (p=0.0002 and p=0.040 respectively). There was no association between specific gB subtypes in all patients groups (p=0.463). There was no correlation between HCMV genotypes and the outcome.     

Sequence variability of the alpha-chemokine UL146 from clinical strains of human cytomegalovirus

Human cytomegalovirus (HCMV) is a ubiquitous pathogen that infects a variety of cell types in vivo. A region (referred to as UL/b') present in the Toledo strain of HCMV and low passage clinical isolates contains 22 additional genes, which are absent in the highly passaged laboratory strain AD169. One of these genes, UL146, encodes an alpha-chemokine. PCR amplification and sequencing of this gene from serial samples obtained from transplant recipients and samples from infants with suspected congenital HCMV infection, revealed that UL146 is a hypervariable gene in vivo. However, genetic changes were highly conserved in individuals and in renal transplant recipients multiple genotypes of UL146 were present. The majority of strains characterized maintained the conserved ELRCXC motif present in the Toledo strain of HCMV. These results provide further evidence that AD169 does not represent the authentic virus in vivo and although Towne and Toledo are more representative, major genetic differences still exist. Mixed populations of HCMV strains occur in vivo so cloning of these strains is essential if an authentic genotype is to be defined.     

人巨细胞病毒UL148基因在临床低传代分离株中的多态性研究

目的 研究人巨细胞病毒(HCMV)UL148序列在临床低传代分离株中的多态性。方法 对38株经荧光定量PCR方法(Q-PCR)检测HCMV-DNA为阳性的临床低传代分离株的细胞培养上清液进行HCMV UL148全序列PCR扩增，并对PCR扩增产物进行序列测定及分析。结果 38株临床低传代分离株有17株PCR扩增阳性，与HCMV Toledo株进行序列比较分析，17株临床分离株ULl48开放阅读框架(ORF)长度均与Toledo株相同。其编码蛋白的氨基酸变异率为0．3％～2．3％。所有分离株均有蛋白翻译后修饰位点的新增或缺失。与Toledo株相比17株临床分离株UL148蛋白质二级结构预测结果均为第15～18位之间由α-螺旋变为β-折叠。结论 17株HCMV临床低传代分离株UL148基因及其编码产物的氨基酸序列比较保守，但仍存在一定程度的多态性。