Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India.
Department of Microbiology and Immunology, University at Buffalo, Buffalo, NY, 14203, USA.
Retrovirology. 2021 Apr 9;18(1):9. doi: 10.1186/s12977-021-00553-5.
Maturation inhibitors (MIs) potently block HIV-1 maturation by inhibiting the cleavage of the capsid protein and spacer peptide 1 (CA-SP1). Bevirimat (BVM), a highly efficacious first-in-class MI against HIV-1 subtype B isolates, elicited sub-optimal efficacy in clinical trials due to polymorphisms in the CA-SP1 region of the Gag protein (SP1:V7A). HIV-1 subtype C inherently contains this polymorphism thus conferring BVM resistance, however it displayed sensitivity to second generation BVM analogs.
In this study, we have assessed the efficacy of three novel second-generation MIs (BVM analogs: CV-8611, CV-8612, CV-8613) against HIV-1 subtype B and C isolates. The BVM analogs were potent inhibitors of both HIV-1 subtype B (NL4-3) and subtype C (K3016) viruses. Serial passaging of the subtype C, K3016 virus strain in the presence of BVM analogs led to identification of two mutant viruses-Gag SP1:A1V and CA:I201V. While the SP1:A1V mutant was resistant to the MIs, the CA:I120V mutant displayed partial resistance and a MI-dependent phenotype. Further analysis of the activity of the BVM analogs against two additional HIV-1 subtype C strains, IndieC1 and ZM247 revealed that they had reduced sensitivity as compared to K3016. Sequence analysis of the three viruses identified two polymorphisms at SP1 residues 9 and 10 (K3016: N9, G10; IndieC1/ZM247: S9, T10). The N9S and S9N mutants had no change in MI-sensitivity. On the other hand, replacing glycine at residue 10 with threonine in K3016 reduced its MI sensitivity whereas introducing glycine at SP1 10 in place of threonine in IndieC1 and ZM247 significantly enhanced their MI sensitivity. Thus, the specific glycine residue 10 of SP1 in the HIV-1 subtype C viruses determined sensitivity towards BVM analogs.
We have identified an association of a specific glycine at position 10 of Gag-SP1 with an MI susceptible phenotype of HIV-1 subtype C viruses. Our findings have highlighted that HIV-1 subtype C viruses, which were inherently resistant to BVM, may also be similarly predisposed to exhibit a significant degree of resistance to second-generation BVM analogs. Our work has strongly suggested that genetic differences between HIV-1 subtypes may produce variable MI sensitivity that needs to be considered in the development of novel, potent, broadly-active MIs.
成熟抑制剂（MIs）通过抑制衣壳蛋白和间隔肽 1（CA-SP1）的切割，有效地阻止了 HIV-1 的成熟。贝伐单抗（BVM）是一种高效的抗 HIV-1 亚型 B 分离株的首创类 MIs，由于 Gag 蛋白 CA-SP1 区域的多态性（SP1：V7A），在临床试验中疗效并不理想。HIV-1 亚型 C 固有地含有这种多态性，从而赋予了 BVM 耐药性，但它对第二代 BVM 类似物表现出敏感性。
在这项研究中，我们评估了三种新型第二代 MIs（BVM 类似物：CV-8611、CV-8612、CV-8613）对 HIV-1 亚型 B 和 C 分离株的疗效。BVM 类似物对 HIV-1 亚型 B（NL4-3）和 C（K3016）病毒均具有很强的抑制作用。在 BVM 类似物存在的情况下，对 HIV-1 亚型 C、K3016 病毒株进行连续传代，鉴定出两种突变病毒-Gag SP1：A1V 和 CA：I201V。虽然 SP1：A1V 突变体对 MIs 具有耐药性，但 CA：I120V 突变体表现出部分耐药性和 MIs 依赖性表型。进一步分析三种病毒对另外两种 HIV-1 亚型 C 株（IndieC1 和 ZM247）的 BVM 类似物活性，发现它们的敏感性与 K3016 相比有所降低。对这三种病毒的序列分析发现 SP1 残基 9 和 10 处有两个多态性（K3016：N9，G10；IndieC1/ZM247：S9，T10）。K3016 的 N9S 和 S9N 突变体对 MIs 的敏感性没有变化。另一方面，K3016 中甘氨酸 10 残基被替换为苏氨酸降低了其 MIs 敏感性，而 IndieC1 和 ZM247 中 SP1 10 残基的甘氨酸被替换为苏氨酸则显著增强了其 MIs 敏感性。因此，HIV-1 亚型 C 病毒中 Gag-SP1 的特定甘氨酸 10 残基决定了其对 BVM 类似物的敏感性。
我们发现 Gag-SP1 第 10 位特定甘氨酸与 HIV-1 亚型 C 病毒的 MIs 敏感表型有关。我们的研究结果表明，固有地对 BVM 具有耐药性的 HIV-1 亚型 C 病毒也可能同样容易对第二代 BVM 类似物表现出显著程度的耐药性。我们的工作强烈表明，HIV-1 亚型之间的遗传差异可能产生不同的 MIs 敏感性，在新型、有效、广泛活性的 MIs 的开发中需要考虑这一点。
