RETROVIRUSES AND THEIR RECEPTORS

涉及体内移植或体外暴露于猪组织或细胞的I期临床试验正在进行中。由于所有猪的基因组中都携带内源性逆转录病毒，称为猪内源性逆转录病毒或PERV，这些异种移植程序存在暴露和传播到PERV的风险。我们先前已经证明，这种正常潜伏的逆转录病毒在猪外周血单个核细胞(PBMC)暴露于有丝分裂物质后激活。我们现在已经证明，在体外将猪PBMC来源的PERV通过人类细胞系传代后，PERV的变异体被选择在人类细胞系上具有增强的复制特性。这对异种移植环境中PERV跨物种传播和可能适应人类宿主具有重要意义。此外，我们还扩展了对猪血浆衍生产品Hyate：C(猪第VIII因子)的分析。我们现在已经证明，猪血浆携带从6/6 NIH小型猪血浆中分离到的传染性PERV。在这项研究中，我们能够证明，尽管猪血浆携带所有三个包膜类PERV-A、B和C的编码序列(A和B已被证明与人类嗜性有关)，但在培养试验中只能分离到嗜猪的PERV-C病毒。最后，我们已经开始研究一种动物模型，通过与斯克里普斯研究所的丹·萨拉蒙合作，研究体内PERV感染特性。利用NOD/SCID小鼠，我们已经证明了PERV从嵌入到RGD模板上的猪胰岛到植入到RGD模板上的293细胞的小鼠体内传播，以及PERV到一些小鼠组织的传播。这是首次发表的关于PERV在体内的传染性和复制的证明。

Phase I clinical trials involving in vivo transplantation or ex vivo exposure to swine tissues or cells are underway. Since all pigs carry in their genome endogenous retroviruses, called porcine endogenous retrovirus or PERV, these xenotransplantation procedures carry the risk of exposure and transmission to PERV. We have previously shown that activation of this normally latent retrovirus occurs after exposure of pig primary peripheral blood mononuclear cells (PBMC) to mitogenic agents. We now have shown that after in vitro passaging of pig PBMC-derived PERV through a human cell line that variants of PERV are selected with enhanced replication properties on the human cell line. This has important implications about cross-species transmission and possible adaptation of PERV to a human host in the xenotransplantation setting. In addition, we have extended our analysis of the porcine plasma-derived product, Hyate:C (porcine factor VIII). We now have shown that porcine plasma carries infectious PERV that was isolated from plasma of 6/6 NIH mini pigs. In this study, we were able to demonstrate that although the porcine plasma carried the coding sequences for all three envelope classes, PERV-A, B, and C (A and B have been shown to be responsible for the human tropism), only the pig-tropic PERV-C virus could be isolated in the culture assay. Finally, we have started to investigate an animal model to study PERV infection properties in vivo through a collaboration with Dan Salamon at The Scripps Institute. Using the NOD/SCID mouse, we have demonstrated in vivo transmission of PERV from porcine pancreatic islets embedded onto RGD templates to 293 cells implanted onto RGD templates at distal sites in the mouse, as well as transmission of PERV to some murine tissues. This is the first published demonstration of in vivo infectivity and replication of PERV.