Origin and molecular evolution of primate lentiviruses-Genetic analysis of HIV/HTLV in Africa

阐明SIV和HIV的起源对于理解HIV的发病机制和AIDS的全球传播至关重要。中非被认为是HIV-1的发源地，灵长类慢病毒从自然感染的猴子到人类的人畜共患传播被认为是产生HIV的原因。在这项研究中，新分离的SIV，命名为SIVmnd 98 CM 16，99 CM 31，99 CM 32，99 CM 33从四个家庭饲养的山狮（Mandrillus sphinx）在喀麦隆进行了检查的遗传特征，从33个山狮血浆中的四个有交叉反应抗体的HIV-2，这四个也有弱交叉反应抗体的HIV-1。为了确认猴子是否真的携带SIV，扩增亚基因组pol（整合酶，288-bp）基因并测序。系统发育分析表明，4个加蓬SIVmnds没有聚类与以前报道的SIVmndGB 1从一个山鸡在加蓬，但形成了一个新的独立的谱系。对分离的SIV进行全基因组测序，发现其基因组结构与HIV-2/SIVsmm相似，具有vpx和vpr。基于基因组的不同部分构建系统发育树时，有些基因组序列相似，有些基因组序列模式不同; SIVmnd 98 CM 16明显包含3个不同的区域，与SIVrcm和SIVmndGB 1/SIVsun/SIVlhoest形成一个新的独立谱系。这种镶嵌结构可能是由于三个不同的SIV谱系之间的重组，并提供了证据，在过去的猿-猿跨物种传播。

Elucidation of the origins of SIV and HIV is fundamental to the understanding of HIV pathogenesis and the worldwide spread of AIDS. Central Africa is thought to be the birth place of HIV-1, and zoonotic transmissions of primate lentiviruses from naturally infected monkeys to human were suggested to have generated HIV. In this study, the genetic characterization of newly isolated SIV, termed SIVmnd98CM16, 99CM31, 99CM32, 99CM33 from four household pet mandrills (Mandrillus sphinx) in Cameroon were examined.Plasma from four out of 33 mandrills had cross-reactive antibodies to HIV-2, and two of these four had also weakly cross-reactive antibodies to HIV-1. To confirm whether the monkeys truly carry SIV, the subgenomic pol (integrase, 288-bp) gene was amplified and sequenced. Phylogenetic analysis revealed that four Cameroonian SIVmnds did not cluster with previously reported SIVmnd GB1 from a mandrill in Gabon but formed a new independent lineage. When the full genome of the isolated SIV was sequenced, its genomic organization was found to be similar to that of HIV-2/SIVsmm possessing vpx and vpr. When phylogenetic trees were constructed based on different parts of the genome, some of them were similar but some showed patterns that were different from each other; SIVmnd98CM16 evidently comprised three different regions which formed a new independent lineage clustered with SIVrcm and with SIVmndGB1/SIVsun/SIVlhoest. This mosaic structure might be due to recombination among three different SIV lineages and provides evidence of simian-simian cross-species transmission in the past.