Sequentially immune-induced antibodies could cross-neutralize SARS-CoV-2 variants

摘要

Background:The Omicron(B.1.1.529)SARS-COV-2 variant has raised serious concerns because of its unprecedented rapid rate of spreading and the fact that there are 36 mutations in the spike protein.Since the vaccine-induced neutralizing antibody targets are the spike protein,this may lead to the possibility of vaccine-induced hu-moral immunity escape.Methods:We measured the neutralizing activity in vitro for Omicron and compared this with wild type(WH-09)and Delta variants in human and monkey sera from different types of immunity.The monkey sera samples were collected at 1 and 3 months post three-dose inactivated(PiCoVacc)and recombinant protein(ZF2001)vaccination.Human sera were collected from 1 month post three-dose inactivated vaccination.Results:In inactivated vaccine sera,at 1/3 months post three-dose,geometric mean titers(GMTs)of neutralization antibody(NAb)against the Omicron variant were 4.9/5.2-fold lower than those of the wild type.In recombinant protein vaccine sera,GMTs of NAb against Omicron were 15.7/8.9-fold lower than those of the wild type.In human sera,at 1 month post three-dose inactivated vaccination,GMTs of NAb against Omicron were 3.1-fold lower than those of the wild type.Conclusion:This study demonstrated that despite a reduction in neutralization titers,cross-neutralizing activity against Omicron and Delta variants was still observed after three doses of inactivated and recombinant protein vaccination.