Functional analysis of the chemokine and chemokine receptors encoded by human herpesvirus 6.

人类疱疹病毒6型（Human henpesvirus 6，HHV-6）属于β疱疹病毒亚科，在体外主要感染T细胞和单核细胞，可引起急性和潜伏性感染。HHV-6的两种变体已根据几种性质的差异加以区分。我们测定了HHV-6变异株B（HHV-6 B）HST株的DNA全序列，并与变异株A株U1102的序列进行了比较。在整个HHV-6基因组的161，573-bp连续序列中共鉴定出115个潜在的开放阅读框架（ORF），包括一些在氨基酸同一性上具有显著差异的基因。菌株HST的U83编码趋化因子，其作为单核细胞的化学引诱物起作用。类似地，菌株U1102的U83编码趋化因子同源物，但其不含信号肽序列。因此，菌株U1102的U83可能不分泌，因此不能发挥其趋化活性。如果U83在v中起化学引诱剂的作用， ...更多信息 在体内，HHV-6可能容易通过细胞间感染传播，即使在中性抗体存在下也是如此。Z29株的U12是截短的，不编码HST株所编码的CC趋化因子的钙动员受体，Z29株的致病机制尚不清楚。这些结果提示U12的产物可能通过与CC-趋化因子结合，通过跨膜信号转导在HHV-6的发病机制中起重要作用。U83基因含有一个ORF，编码一个113个氨基酸的肽，从第一个甲硫氨酸开始，含有一个可能的信号肽和典型的半胱氨酸残基的趋化因子的特征。反转录-PCR分析和免疫荧光抗体检测均表明，编码的蛋白质是一个晚期蛋白。将ORF U83基因与FC基因融合后转染COS-7细胞，获得融合蛋白，并从转染细胞上清中纯化融合蛋白，以检测其生物学功能。纯化的蛋白质能够诱导THP-1细胞中的瞬时钙动员和趋化激活THP-1细胞。这些发现表明，U83蛋白可能在HHV-6的体内繁殖中发挥重要作用，通过激活和运输单核细胞到病毒复制的位点，从而帮助开发高效的病毒生产机制。少

Human henpesvirus 6(HHV-6), which belongs to the betaherpesvirus subfamily and infects mainly T cells and mononuclear cells in vitro, causes acute and latent infections. Two variants of HHV-6 have been distinguished on the basis of differences in several properties. We have determined the complete DNA sequence of HHV-6 variant B(HHV-6B)strain HST, the causative agent of exanthem subitum, and compared the sequence with that of variant A strain U1102. A total of 115 potential open reading frames(ORFs)were identified within the 161,573-bp contiguous sequence of the entire HHV-6 genome, including some genes with remarkable differences in amino acid identity. U83 of strain HST encodes a chemokine, which functions as a chemoattractant for monocytes. Similarly, U83 of strain U1102 encodes a chemokine homolog, but it does not contain a signal peptide sequence. Thus, U83 of strain U1102 may not be secreted and thus cnnot exert its chemotactic activity. If U83 functions as a chemoattractant in v … More ivo, it is possible that HHV-6 can easily spread through cell-to-cell infection, even in the presence of neutral antibodies. U12 of strain Z29 is truncated and dose not encode a calcium-mobilizing receptor for CC-chemokines which is encoded by that of strain HST.Nobody know the pathogenesis of strain Z29. These findigns suggested that the product of U12 may play an important role in the pathogenesis of HHV-6 through transmembrane signaling by binding with CC-chemokines.We have cloned the U83 gene and analyzed the biological function of this gene. The U83 gene contained an ORF encoding a 113-amino-acid peptide, starting at the first methionine and containing a possible signal peptide and the typical cysteine residues chanacteristic of the chemokines. Reverse transcription-PCR analysis of mRNA and immunofluorescent-antibody testing of infected cells both indicated that the encoded protein was a late protein. The ORF U83 gene fused to the FC gene was expressed as a fusion protcin in COS-7 cells by tnansfection, and the fusion protein was purified from the supernatant of transfected cells to test its biological function. The purified protein was capable of inducing transient calcium mobilization in THP-1 cells and of chemotactically activating THP-1 cells. These findings suggested that the U83 protein might play an important role in HHV-6 propagation in vivo by activating and trafficking mononuclear cells to sites of vira replication, thus aiding the development of superbly efficient virus production mechanisms. Less