Homologous and heterologous booster vaccinations of S-268019-b, a recombinant S protein-based vaccine with a squalene-based adjuvant, enhance neutralization breadth against SARS-CoV-2 Omicron subvariants in cynomolgus macaques

Vaccine. 2022 Dec 12;40(52):7520-7525. doi: 10.1016/j.vaccine.2022.10.092. Epub 2022 Nov 8.

Abstract

SARS-CoV-2 Omicron subvariants such as BA.2.12.1, BA.4 and BA.5 have been spreading rapidly and become dominant worldwide. Here we report the homologous or heterologous booster effects of S-268019-b, a recombinant spike protein vaccine with the squalene-based adjuvant A-910823 in cynomolgus macaques. In macaques which had been primed with S-268019-b or mRNA vaccines, boosting with S-268019-b enhanced neutralizing antibodies (NAb) against ancestral SARS-CoV-2. Since boosting with the antigen without adjuvant did not efficiently restore NAb titers, adjuvant A-910823 was essential for the booster effect. Importantly, boosting with S-268019-b enhanced NAb against all of the Omicron subvariants we tested, including BA.2.12.1, BA.4 and BA.5, in comparison to two vaccine doses. Additionally, expansion of Omicron-specific B cells was confirmed after boosting with S-268019-b. These results indicate that a booster dose of S-268019-b with the adjuvant enhances the neutralization breadth.

Keywords: Cynomolgus macaques; Heterologous booster; Homologous booster; S-268019-b; SARS-CoV-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic
  • Animals
  • Antibodies, Neutralizing
  • COVID-19* / prevention & control
  • Macaca fascicularis
  • SARS-CoV-2
  • Squalene*
  • Vaccination
  • Vaccines, Synthetic / genetics

Substances

  • Squalene
  • Vaccines, Synthetic
  • Adjuvants, Immunologic
  • Antibodies, Neutralizing