Investigating antigenic features of the SARS-CoV-2 isolated in Russian Federation in 2021–2022 by hyperimmune mouse serum neutralisation

Introduction. The rapid spread of a new coronavirus infection among populations in many countries worldwide has contributed to the genetic evolution virus, resulting emergence multiple variants SARS-CoV-2 coronavirus. Mutations viral genome can affect ability virus bypass immune system and complicate development diagnostic prophylactic drugs. Data on neutralizing activity sera obtained against previously circulating relation current strains may serve as scientific basis for selection antigens vaccine development. aim this work was study cross-reactivity belonging different variants, which were isolated territory Russian Federation during 20202022 neutralization reaction using mouse hyperimmune sera. Materials methods. Ten used (three non-VOC strains, alpha, beta, gamma, delta, delta+AY, omicron 1 2). hCoV-19/Australia/VIC01/2020 strain (Wuhan) included prototypical variant. BALBc mice immunized with inactivated concentrated antigen mixed 1:1 adjuvant, virus-like immunostimulatory complex based Quillaja saponaria (Quillaja saponaria). antibody titer determined reaction. Results. Essential decrease antibodies specific non-vOC revealed beta VOC lesser degree alpha gamma variants. differences level are not significant themselves, there no differences. Neutralizing delta decreased 4-fold. 2 prototype variant reduced 18-fold, 12-fold, more than 30-fold; other it even lower. Conclusions. results testify presence between lines Wuhan, gamma; is weaker led antigenic cross-links earlier These findings explain low efficacy vaccines Wuhan strain, synthetic immunogens, recombinant proteins have caused rise morbidity since early 2022, well cases re-infection humans