The pandemic caused by SARS-CoV-2 (SCoV-2) has impacted the world in many ways and the virus continues to evolve and produce novel variants with the ability to cause frequent global outbreaks. Although the advent of the vaccines abated the global burden, they were not effective against all the variants of SCoV-2. This trend warrants shifting the focus on the development of small molecules targeting the crucial proteins of the viral replication machinery as effective therapeutic solutions. The PLpro is a crucial enzyme having multiple roles during the viral life cycle and is a well-established drug target. In this study, we identified 12 potential inhibitors of PLpro through virtual screening of the FDA-approved drug library. Docking and molecular dynamics simulation studies suggested that these molecules bind to the PLpro through multiple interactions. Further, IC50 values obtained from enzyme-inhibition assays affirm the stronger affinities of the identified molecules for the PLpro. Also, we demonstrated high structural conservation in the catalytic site of PLpro between SCoV-2 and Human Coronavirus 229E (HCoV-229E) through molecular modelling studies. Based on these similarities in PLpro structures and the resemblance in various signalling pathways for the two viruses, we propose that HCoV-229E is a suitable surrogate for SCoV-2 in drug-discovery studies. Validating our hypothesis, Mefloquine, which was effective against HCoV-229E, was found to be effective against SCoV-2 as well in cell-based assays. Overall, the present study demonstrated Mefloquine as a potential inhibitor of SCoV-2 PLpro and its antiviral activity against SCoV-2. Corroborating our findings, based on the in vitro virus inhibition assays, a recent study reported a prophylactic role for Mefloquine against SCoV-2. Accordingly, Mefloquine may further be investigated for its potential as a drug candidate for the treatment of COVID.
由严重急性呼吸系统综合症-CoV-2(SCoV-2)引起的大流行对世界造成了多方面的影响,而且该病毒仍在不断进化,并产生了新的变种,能够在全球范围内频繁爆发。虽然疫苗的出现减轻了全球的负担,但它们并不能有效抵抗 SCoV-2 的所有变种。在这种趋势下,开发针对病毒复制机制关键蛋白的小分子药物成为有效的治疗方案。PLpro 是一种在病毒生命周期中发挥多重作用的关键酶,也是一种成熟的药物靶点。在这项研究中,我们通过对美国 FDA 批准的药物库进行虚拟筛选,确定了 12 种潜在的 PLpro
抑制剂。对接和分子动力学模拟研究表明,这些分子通过多种相互作用与 PLpro 结合。此外,从酶抑制实验中获得的 IC50 值也证实了已确定的分子对 PLpro 具有更强的亲和力。此外,我们还通过分子建模研究证明,SCoV-2 和人类冠状病毒 229E(HCoV-229E)的 PLpro 催化位点结构高度一致。基于 PLpro 结构的相似性和两种病毒各种信号通路的相似性,我们认为 HCoV-229E 是药物发现研究中 SCoV-2 的合适替代物。在基于细胞的试验中,我们发现对 HCoV-229E 有效的甲
氟喹也对 SCoV-2 有效,这验证了我们的假设。总之,本研究证明了甲
氟喹是 SCoV-2 PLpro 的潜在
抑制剂,对 SCoV-2 具有抗病毒活性。与我们的研究结果相印证的是,基于体外病毒抑制实验,最近的一项研究报道了甲
氟喹对 SCoV-2 的预防作用。因此,可以进一步研究甲
氟喹作为治疗 COVID 候选药物的潜力。