Tulimilli SubbaRao V, Dallavalasa Siva, Basavaraju Chaithanya G, Kumar Rao Vinay, Chikkahonnaiah Prashanth, Madhunapantula SubbaRao V, Veeranna Ravindra P
Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR) Laboratory (DST-FIST Supported Center), Department of Biochemistry (DST-FIST Supported Department), JSS Medical College, JSS Academy of Higher Education & Research (JSS AHER), Mysuru 570004, Karnataka, India.
Department of Medical Genetics, JSS Medical College & Hospital, JSS Academy of Higher Education & Research (JSS AHER), Mysore 570015, Karnataka, India.
Vaccines (Basel). 2022 Oct 19;10(10):1751. doi: 10.3390/vaccines10101751.
The incidence and death toll due to SARS-CoV-2 infection varied time-to-time; and depended on several factors, including severity (viral load), immune status, age, gender, vaccination status, and presence of comorbidities. The RNA genome of SARS-CoV-2 has mutated and produced several variants, which were classified by the SARS-CoV-2 Interagency Group (SIG) into four major categories. The first category; “Variant Being Monitored (VBM)”, consists of Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), Epsilon (B.1.427, B.1.429), Eta (B.1.525), Iota (B.1.526), Kappa (B.1.617.1), Mu (B.1.621), and Zeta (P.2); the second category; “Variants of Concern” consists of Omicron (B.1.1.529). The third and fourth categories include “Variants of Interest (VOI)”, and “Variants of High Consequence (VOHC)”, respectively, and contain no variants classified currently under these categories. The surge in VBM and VOC poses a significant threat to public health globally as they exhibit altered virulence, transmissibility, diagnostic or therapeutic escape, and the ability to evade the host immune response. Studies have shown that certain mutations increase the infectivity and pathogenicity of the virus as demonstrated in the case of SARS-CoV-2, the Omicron variant. It is reported that the Omicron variant has >60 mutations with at least 30 mutations in the Spike protein (“S” protein) and 15 mutations in the receptor-binding domain (RBD), resulting in rapid attachment to target cells and immune evasion. The spread of VBM and VOCs has affected the actual protective efficacy of the first-generation vaccines (ChAdOx1, Ad26.COV2.S, NVX-CoV2373, BNT162b2). Currently, the data on the effectiveness of existing vaccines against newer variants of SARS-CoV-2 are very scanty; hence additional studies are immediately warranted. To this end, recent studies have initiated investigations to elucidate the structural features of crucial proteins of SARS-CoV-2 variants and their involvement in pathogenesis. In addition, intense research is in progress to develop better preventive and therapeutic strategies to halt the spread of COVID-19 caused by variants. This review summarizes the structure and life cycle of SARS-CoV-2, provides background information on several variants of SARS-CoV-2 and mutations associated with these variants, and reviews recent studies on the safety and efficacy of major vaccines/vaccine candidates approved against SARS-CoV-2, and its variants.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的发病率和死亡人数随时间变化；并取决于几个因素，包括严重程度（病毒载量）、免疫状态、年龄、性别、疫苗接种状况和合并症的存在。SARS-CoV-2的RNA基因组发生了突变，并产生了几种变体，这些变体被SARS-CoV-2跨部门小组（SIG）分为四大类。第一类；“正在监测的变体（VBM）”，包括阿尔法（B.1.1.7）、贝塔（B.1.351）、伽马（P.1）、德尔塔（B.1.617.2）、伊普西龙（B.1.427、B.1.429）、伊塔（B.1.525）、约塔（B.1.526）、卡帕（B.1.617.1）、缪（B.1.621）和泽塔（P.2）；第二类；“关注变体”包括奥密克戎（B.1.1.529）。第三类和第四类分别包括“感兴趣的变体（VOI）”和“具有高后果的变体（VOHC）”，目前这些类别下没有分类的变体。VBM和VOC的激增对全球公共卫生构成了重大威胁，因为它们表现出毒力、传播性、诊断或治疗逃逸的改变，以及逃避宿主免疫反应的能力。研究表明，某些突变会增加病毒的传染性和致病性，如SARS-CoV-2奥密克戎变体的情况所示。据报道，奥密克戎变体有>60个突变，其中刺突蛋白（“S”蛋白）至少有30个突变，受体结合域（RBD）有15个突变，导致其能快速附着于靶细胞并逃避免疫。VBM和VOC的传播影响了第一代疫苗（ChAdOx1、Ad26.COV2.S、NVX-CoV2373、BNT162b2）的实际保护效力。目前，关于现有疫苗对SARS-CoV-2新变体有效性的数据非常稀少；因此迫切需要进行更多研究。为此，最近的研究已开始调查，以阐明SARS-CoV-2变体关键蛋白的结构特征及其在发病机制中的作用。此外，正在进行深入研究，以制定更好的预防和治疗策略，以阻止由变体引起的COVID-19的传播。本综述总结了SARS-CoV-2的结构和生命周期，提供了关于SARS-CoV-2几种变体及其相关突变的背景信息，并综述了最近关于批准用于对抗SARS-CoV-2及其变体的主要疫苗/候选疫苗的安全性和有效性的研究。
