Steep Decline in Binding Capability of SARS-CoV-2 Omicron Variant (B.1.1.529) RBD to the Antibodies in Early COVID-19 Convalescent Sera and Inactivated Vaccine Sera

Abstract

A new SARS-CoV-2 variant B.1.1.529 was named by the WHO as Omicron and classified as a Variant of Concern (VOC) on 26 November 2021. Because this variant has more than 50 mutations, including 30 mutations on the spike, it has generated a lot of concerns on the potential impacts of the VOC on COVID-19. Here through ELISA assays using the recombinant RBD proteins with sequences the same to that of SARS-CoV-2 WIV04 (lineage B.1), the Delta variant and the Omicron variant as the coating antigens, the binding capabilities between the RBDs and the antibodies in COVID-19 convalescent sera and vaccine sera after two doses of the inactivated vaccine produced by Sinopharm WIBP are compared with each other. The results showed that the Omicron variant may evade antibodies induced by the ancestral strain and by the inactivated vaccine, with significant reduction in the binding capability of its RBD much greater than that of the Delta variant.

Understanding the omicron variant (B.1.1.529) of SARS-CoV-2: Mutational impacts, concerns, and the possible solutions

“…According to recent research, the Omicron variation can avoid antibodies generated by the original strain and vaccination [ 15 ]. With just two mutations in the RBD, the Delta variant shows a slight reduction in the RBD's binding capacity to both vaccinated and convalescent sera, which is consistent with recent research [ 15 , 47 ]. On the other hand, omicron successfully evades antibodies induced by ancestral variations and inactivated vaccines, despite a significant reduction in the binding potential to its RBD [ 15 , 47 ].…”

“…With just two mutations in the RBD, the Delta variant shows a slight reduction in the RBD's binding capacity to both vaccinated and convalescent sera, which is consistent with recent research [ 15 , 47 ]. On the other hand, omicron successfully evades antibodies induced by ancestral variations and inactivated vaccines, despite a significant reduction in the binding potential to its RBD [ 15 , 47 ]. Several recent findings indicate that the omicron variant shows an unprecedented degree of neutralizing antibody escape [ 48 ]; they also suggest that boosting and promoting affinity maturation of antibodies in persons who have previously been infected or vaccinated with the use of existing Wuhan-hu-1–based vaccine immunogens will provide additional protection against infection with the omicron variant and subsequent disease [ 49 ].…”

Neutralizing Antibody Response to BBIBP-CorV in Comparison with COVID-19 Recovered, Unvaccinated Individuals in a Sample of the Pakistani Population

“…Regardless, in the absence of established genomic surveillance mechanisms in the country, data on the prevalence and types of SARS-CoV-2 mutations in Pakistan has remained sparse at all times. Subsequently arising variants have shown reduced titers to vaccines, and it is thus entirely possible that testing for antibody titers with these spike protein mutations might have further reduced the detected antibody titers in Group I [ 46 , 47 , 48 , 49 ] and magnified the inter-group difference.…”

Omicron variant (B.1.1.529) and its sublineages: What do we know so far amid the emergence of recombinant variants of SARS-CoV-2?

“…A significant number of mutations in the S-protein, including fifteen mutations in the RBD of the Omicron variant, have been linked to immune escape. Significant decreases in neutralizing activity of sera from vaccinated or previously infected people, which may suggest lower protection from infection, are expected based on the number of substitutions, their position, and evidence from other variations with similar spike protein mutations [204 ] .…”