McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, McGill University Health Centre, Montreal, Que., Canada.
Intervirology. 2013;56(4):258-64. doi: 10.1159/000348513. Epub 2013 May 8.
The host protein APOBEC3G (A3G) can limit HIV-1 replication. Its protective effect is overcome by the HIV-1 'viral infectivity factor' (Vif), which targets A3G for proteosomal degradation. Although Vif is considered to be essential for HIV-1 replication, the effect of Vif variability among commonly used HIV-1 molecular clones of different genetic backgrounds on viral infectiousness and pathogenesis has not been fully determined.
We cloned the intact Vif coding regions of available molecular clones of different subtypes into expression vectors. Δvif full-length HIV-1 clonal variants were generated from corresponding subtype-specific full-length molecular clones. Replication-competent viruses were produced in 293T cells in the presence or absence of A3G, with Vif being supplied by the full-length HIV-1 clone or in trans. The extent of A3G-mediated restriction was then determined in a viral replication assay using a reporter cell line.
In the absence of A3G, Vif subtype origin did not impact viral replication. In the presence of A3G the subtype origin of Vif had a differential effect on viral replication. Vif derived from a subtype C molecular clone was less effective at overcoming A3G-mediated inhibition than Vif derived from either subtype B or CRF02_AG molecular clones.
宿主蛋白 APOBEC3G（A3G）可以限制 HIV-1 的复制。其保护作用被 HIV-1 的“病毒感染力因子”（Vif）所克服，Vif 可将 A3G 靶向蛋白酶体降解。尽管 Vif 被认为是 HIV-1 复制所必需的，但不同遗传背景的常用 HIV-1 分子克隆之间 Vif 变异性对病毒感染力和发病机制的影响尚未完全确定。
我们将不同亚型的现有分子克隆的完整 Vif 编码区克隆到表达载体中。从相应的亚型特异性全长分子克隆中生成了 Δvif 全长 HIV-1 克隆变体。在存在或不存在 A3G 的情况下，在 293T 细胞中产生具有复制能力的病毒，Vif 由全长 HIV-1 克隆或转染提供。然后在使用报告细胞系的病毒复制测定中确定 A3G 介导的限制程度。
在不存在 A3G 的情况下，Vif 亚型来源不会影响病毒复制。在存在 A3G 的情况下，Vif 的亚型来源对病毒复制有不同的影响。与源自 B 亚型或 CRF02_AG 分子克隆的 Vif 相比，源自 C 亚型分子克隆的 Vif 克服 A3G 介导的抑制作用的效果较差。
