MOLECULAR ANALYSIS OF THIRD VARIABLE ENVELOPE REGIONS OF SIV

虽然HIV-1的V3序列是主要的基因 关于病毒细胞特异性的决定因素，我们知之甚少 SIV V3序列的作用。为了了解SIV V3序列的作用， 我们重点研究了一种分子克隆的SIV，命名为EvT3，它 显示独特的V3序列、体外细胞特异性和致病性 在活体内的潜力。与SIVmac239相比，EvT3 V3有6个氨基酸 SIV V3的32个氨基酸范围内的替换。在文化上， EvT3不能在高表达的人T细胞系中复制 对SIVmac239感染敏感。当试验性感染到 恒河猴EvT3，而不是SIVmac239，引起严重和快速 CD4+T细胞耗尽。我们已经研究了EvT3的意义 V3序列在通过构建确定生物特性中的作用 在EvT3和SIVmac239之间的V3重组病毒。我们的数据显示 已证明EvT3 V3序列是导致不能 在体外的人类T细胞系中复制，它们也是必不可少的 用于在体内诱导CD4+T细胞耗竭。有趣的是，EvT3 V3比SIVmac239 V3更具正电荷和亲水性，SIVmac239 V3 具有与嗜T细胞HIV-1的V3相似的特性。最近，它已经 研究表明，含有带正电荷的V3的嗜T细胞HIV-1 序列利用CXCR4作为病毒进入的共同受体。一致 利用V3序列的性质，我们发现EvT3是有效的 已使用CXCR4进行病毒进入。相比之下，SIVmac239利用CCR5 但不是类似于偏嗜性HIV-1的CXCR4。我们使用V3的数据 重组病毒表明不同的辅受体用途 EvT3和SIVmac239之间的差异也由它们的V3序列决定。 这些数据表明，SIV V3序列在 检测病毒的细胞特异性、致病潜能和 共同受体的用法。我们目前正在努力确定 V3中决定猪生物学特性的遗传决定因素(S) SIV，并进一步研究其背后的生化基础 V3与辅受体之间的相互作用 体外测定细胞特异性和可能的致病作用 在活体内的潜力。

Although V3 sequences of HIV-1 are the principal genetic determinants of the viral cell specificity, little is known about the role of SIV V3 sequences. To understand the role of SIV V3 sequences, we have focused on a molecularly cloned SIV, designated as EvT3, which displays unique V3 sequences, cell specificity in vitro and pathogenic potential in vivo. Compared to SIVmac239, EvT3 V3 has six amino acid substitutions within the 32 amino acid stretch of SIV V3. In culture, EvT3 does not replicate in human T cell lines that are highly sensitive to SIVmac239 infection. When experimentally infected into rhesus macaques, EvT3, but not SIVmac239, induces severe and rapid CD4+ T cell depletion. We have investigated the significance of EvT3 V3 sequences in determining the biological properties by construction of V3 recombinant viruses between EvT3 and SIVmac239. Our data have documented that EvT3 V3 sequences are responsible for the inability to replicate in human T cell lines in vitro, and they are also essential for induction of CD4+ T cell depletion in vivo. Interestingly, EvT3 V3 is more positively charged and hydrophilic than SIVmac239 V3, which has a property similar to V3 of T cell-tropic HIV-1. Recently, it has been shown that T cell-tropic HIV-1 containing positively charged V3 sequences utilized CXCR4 as a co-receptor for virus entry. Consistent with the properties of V3 sequences, we found that EvT3 efficiently utilized CXCR4 for virus entry. In contrast, SIVmac239 utilized CCR5 but not CXCR4 similar to Mm-tropic HIV-1. Our data using V3 recombinant viruses indicated that the distinct co-receptor usages between EvT3 and SIVmac239 are also determined by their V3 sequences. These data indicate that SIV V3 sequences play important roles in determining the viral cell specificity, pathogenic potential and co-receptor usages. We are currently making efforts to identify the genetic determinant(s) in V3 determining the biological properties of SIV, and further investigating the biochemical basis underlying the interaction between V3 and co-receptor which is important in determining the cell specificity in vitro and possibly pathogenic potential in vivo.