CoVac501, a self-adjuvanting peptide vaccine conjugated with TLR7 agonists, against SARS-CoV-2 induces protective immunity

Abstract

Safe, economical and effective vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are needed to achieve adequate herd immunity and halt the pandemic. We have constructed a novel SARS-CoV-2 vaccine, CoVac501, which is a self-adjuvanting peptide vaccine conjugated with Toll-like receptor 7 (TLR7) agonists. The vaccine contains two immunodominant peptides screened from receptor-binding domain (RBD) and is fully chemically synthesized. And the vaccine has optimized nanoemulsion formulation, outstanding stability and safety. In non-human primates (NHPs), CoVac501 elicited high and persistent titers of RBD-specific and protective neutralizing antibodies (NAbs), which were also effective to RBD mutations. CoVac501 was found to elicit the increase of memory T cells, antigen-specific CD8+ T cell responses and Th1-biased CD4+ T cell immune responses in NHPs. More importantly, the sera from the immunized NHPs can prevent infection of live SARS-CoV-2 in vitro.

Combatting future variants of SARS-CoV-2 using an in-silico peptide vaccine approach by targeting the spike protein

“…However, these peptides when used alone, generally show low immunogenicity. The targets can be, thus, coupled with innate immune agonists in the form of adjuvants to improve the immunogenic response and ensure a long-term immunity in the host body [37] . Furthermore, in vitro and in vivo evaluation of such a vaccine on animal models through wet lab tests is also needed to verify its efficacy before performing its trial on the infected patients.…”