Fernández-Oliva Alberto, Finzi Andrés, Haim Hillel, Menéndez-Arias Luis, Sodroski Joseph, Pacheco Beatriz
Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, and Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts, USA.
J Virol. 2015 Oct 28;90(2):725-40. doi: 10.1128/JVI.02431-15. Print 2016 Jan 15.
Previous studies have shown that a major block to HIV-1 replication in common marmosets operates at the level of viral entry and that this block can be overcome by adaptation of the virus in tissue-cultured cells. However, our current studies indicate that HIV-1 encounters additional postentry blocks in common marmoset peripheral blood mononuclear cells. Here, we show that the common marmoset APOBEC3G (A3G) and BST2 proteins block HIV-1 in cell cultures. Using a directed-evolution method that takes advantage of the natural ability of HIV-1 to mutate during replication, we have been able to overcome these blocks in tissue-cultured cells. In the adapted viruses, specific changes were observed in gag, vif, env, and nef. The contribution of these changes to virus replication in the presence of the A3G and BST2 restriction factors was studied. We found that certain amino acid changes in Vif and Env that arise during adaptation to marmoset A3G and BST2 allow the virus to replicate in the presence of these restriction factors. The changes in Vif reduce expression levels and encapsidation of marmoset APOBEC3G, while the changes in Env increase viral fitness and discretely favor cell-to-cell transmission of the virus, allowing viral escape from these restriction factors.
HIV-1 can infect only humans and chimpanzees. The main reason for this narrow tropism is the presence in many species of dominant-acting factors, known as restriction factors, that block viral replication in a species-specific way. We have been exploring the blocks to HIV-1 in common marmosets, with the ultimate goal of developing a new animal model of HIV-1 infection in these monkeys. In this study, we observed that common marmoset APOBEC3G and BST2, two known restriction factors, are able to block HIV-1 in cell cultures. We have adapted HIV-1 to replicate in the presence of these restriction factors and have characterized the mechanisms of escape. These studies can help in the development of a novel animal model for in vivo infection of marmosets with HIV-1-like viruses.
先前的研究表明，普通狨猴中HIV-1复制的主要障碍发生在病毒进入阶段，并且通过在组织培养细胞中对病毒进行适应性改造可以克服这一障碍。然而，我们目前的研究表明，HIV-1在普通狨猴外周血单核细胞中还会遇到进入后阶段的其他障碍。在此，我们证明普通狨猴APOBEC3G（A3G）和BST2蛋白在细胞培养中可阻断HIV-1。利用一种定向进化方法，该方法利用HIV-1在复制过程中自然发生突变的能力，我们得以在组织培养细胞中克服这些障碍。在适应性病毒中，在gag、vif、env和nef中观察到了特定变化。研究了这些变化在存在A3G和BST2限制因子的情况下对病毒复制的贡献。我们发现，在适应狨猴A3G和BST2过程中Vif和Env中出现的某些氨基酸变化使病毒能够在这些限制因子存在的情况下进行复制。Vif的变化降低了狨猴APOBEC3G的表达水平和包装，而Env的变化增加了病毒适应性并特别有利于病毒的细胞间传播，使病毒能够逃避这些限制因子。
HIV-1仅能感染人类和黑猩猩。这种狭窄嗜性的主要原因是许多物种中存在主要起作用的因子，即限制因子，它们以物种特异性方式阻断病毒复制。我们一直在探索普通狨猴中HIV-1的障碍，最终目标是在这些猴子中开发一种新的HIV-1感染动物模型。在本研究中，我们观察到普通狨猴的两种已知限制因子APOBEC3G和BST2能够在细胞培养中阻断HIV-1。我们已使HIV-1在这些限制因子存在的情况下进行复制，并对逃逸机制进行了表征。这些研究有助于开发一种新型动物模型，用于在体内用类HIV-1病毒感染狨猴。
