SARS-CoV-2 variants: a new challenge to convalescent serum and mRNA vaccine neutralization efficiency
Maochen Li, Fuxing Lou, Huahao Fan
Abstract
The spike protein of SARS-CoV-2 is the target of antibodies in convalescent and vaccine sera, and 23 mutations in spike protein were reported in the variants B.1.1.7, B.1.351, and P.1 (Fig. Recently, several groups evaluated the effects of convalescent and mRNA vaccine sera on two major circulating SARS-CoV-2 variants B.1.1.7 and B.1.351 (Fig. By 27 March 2021, COVID-19 has caused more than 126.1 million infections and 2,768,409 deaths (https://coronavirus.jhu. edu/), and some countries have already developed vaccines against SARS-CoV-2. Different from the inactivated vaccines approved in China, the western countries are prone to develop mRNA vaccines or viral vector vaccines (e.g., Oxford-AstraZeneca vaccine ChAdOx1 nCoV-19 (AZD1222) and Pfizer-BioNTech vaccine BNT162b2), targeting the spike protein, whose mutations deserve consistent monitoring. Because of the instability of SARS-CoV-2 RNA and error-prone replication, viral mutations appear frequently. 1,2 Until now, 114, 67, and 36 countries have reported the discovery of variants B.1.1.7, B.1.351, and P.1, respectively (covlineages.org/global_report.html). Given these mutations may cause higher viral load and longer infection duration in the infected persons, 3 the effects of B.1.1.7 and B.1.351 variants on virus infection and vaccine efficiency were studied by several groups, respectively (Fig. 1b). 1,2,4,5 Supasa, P. et al. analyzed 180,000 sequences from the COG-UK database (https://www.cogconsortium.uk) and found that B.1.1.7 strain with amino acid 69 and 70 of spike protein deletion (69/70) occupied the dominant position among the three subgroups (the other subgroups lack this deletion), which indicated selective advantages existed in the variation process of SARS-CoV-2. 1 And N501Y mutation existing in all B.1.1.7, B.1.351, and P.1 variants were found to enhance the affinity between receptor-binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2) by about 7-fold compared with wild type (WT).