Summary
Current C0VID-19 vaccines have been associated with a decline in infection rates, prevention of severe disease and a decrease in mortality rates. However, SARS-CoV-2 variants are continuously evolving, and development of new accessible COVID-19 vaccines is essential to mitigate the pandemic. Here, we present data on preclinical studies in mice of a receptor-binding domain (RBD)-based recombinant protein vaccine (PHH-1V) consisting of an RBD fusion heterodimer comprising the B.1.351 and B.1.1.7 SARS-CoV-2 variants formulated in SQBA adjuvant, an oil-in-water emulsion. A prime-boost immunisation with PHH-1V in BALB/c and K18-hACE2 mice induced a CD4+ and CD8+ T cell response and RBD-binding antibodies with neutralising activity against several variants, and also showed a good tolerability profile. Significantly, RBD fusion heterodimer vaccination conferred 100% efficacy, preventing mortality in SARS-CoV-2 infected K18-hACE2 mice, but also reducing Beta, Delta and Omicron infection in lower respiratory airways. These findings demonstrate the feasibility of this recombinant vaccine strategy.
Competing Interest Statement
Authors indicated as 1 are employees of HIPRA, a private pharmaceutical company that develops and manufactures vaccines. CReSA, IrsiCaixa, CMCiB-IGTP, UPF and ICREA have received financial support from HIPRA. Several patent applications have been filed by HIPRA SCIENTIFIC S.L.U. and Laboratorios HIPRA, S.A. on different SARS-CoV-2 vaccine candidates and SARS-CoV-2 subunit vaccines, including the novel recombinant RBD fusion heterodimer PHH-1V. These patent applications are not yet public. Antonio Barreiro, Antoni Prenafeta, Luis Gonzalez, Laura Ferrer, Esther Puigvert, Jordi Palmada, Maria Teresa Prat and Carmen Garriga are the inventors of these patent applications.
Footnotes
↵12 Lead contact: antoni.prenafeta{at}hipra.com
We have reduced the number of characters in the article title and in the abstract. In addition, we have changed the bibliography to Vancouver style (i.e., the references were added with superscript numbers).
