Abstract
The COVID-19 pandemic has highlighted the need for safe and effective vaccines to be rapidly developed and distributed worldwide, especially considering the emergence of new SARS-CoV-2 variants. Protein subunit vaccines have emerged as a promising approach due to their proven safety record and ability to elicit robust immune responses. In this study, we evaluated the immunogenicity and efficacy of an adjuvanted tetravalent S1 subunit protein COVID-19 vaccine candidate composed of the Wuhan, B.1.1.7 variant, B.1.351 variant, and P.1 variant spike proteins in a nonhuman primate model with controlled SIVsab infection. The vaccine candidate induced both humoral and cellular immune responses, with T- and B cell responses mainly peaking post-boost immunization. The vaccine also elicited neutralizing and cross-reactive antibodies, ACE2 blocking antibodies, and T-cell responses, including spike specific CD4+ T cells. Importantly, the vaccine candidate was able to generate Omicron variant spike binding and ACE2 blocking antibodies without specifically vaccinating with Omicron, suggesting potential broad protection against emerging variants. The tetravalent composition of the vaccine candidate has significant implications for COVID-19 vaccine development and implementation, providing broad antibody responses against numerous SARS-CoV-2 variants.
Competing Interest Statement
The authors declare that they have competing interests in relation to the research presented in this manuscript. AG, EK, and MSK are co-founders of GAPHAS PHARMACEUTICAL INC., a private startup company that may potentially benefit from the findings of this research. AG, EK, and MSK have equity in GAPHAS PHARMACEUTICAL INC. However, the authors have taken measures to ensure that the research is conducted objectively and that the data and conclusions presented in this manuscript are not influenced by their competing interests. The study was designed, conducted, and analyzed independently of the company. The authors also declare that GAPHAS PHARMACEUTICAL INC. did not provide financial or material support for this research.