An adjuvanted subunit SARS-CoV-2 spike protein vaccine provides protection against Covid-19 infection and transmission

Abstract

Recombinant protein approaches offer major promise for safe and effective vaccine prevention of SARS-CoV-2 infection. We developed a recombinant spike protein vaccine (called NARUVAX-C19) and characterized its ability when formulated with a nanoemulsion adjuvant to induce anti-spike antibody and T-cell responses and provide protection including against viral transmission in rodent. In mice, NARUVAX-C19 vaccine administered intramuscularly twice at 21-day interval elicited balanced Th1/Th2 humoral and T-cell responses with high titers of neutralizing antibodies against wild-type (D614G) and delta (B.1.617.2) variants. In Syrian hamsters, NARUVAX-C19 provided complete protection against wild-type (D614G) infection and prevented its transmission to naïve animals placed in the same cage as challenged animals. The results contrasted with only weak protection seen with a monomeric spike receptor binding domain (RBD) vaccine even when formulated with the same adjuvant. These encouraging results warrant ongoing development of this Covid-19 vaccine candidate.

A Spike protein-based subunit SARS-CoV-2 vaccine for pets: safety, immunogenicity, and protective efficacy in juvenile cats

“…Nevertheless, the results were highly consistent between the 4 cats in total and the 2 males and 2 females within each group, with statistical differences seen when the adjuvanted vaccine groups were compared to saline controls and/or spike ECD alone immunized animals. Furthermore, the immunogenicity and protective e cacy seen in these juvenile cats of the NARUVAX C-19 vaccine formulation with SWE adjuvant were consistent with the ndings previously obtained for the same vaccine in Syrian hamsters [22]. Another important limitation is the lack of data on long-term protection, on virus transmission and on protection against challenge with the Delta virus variant, as only cross-neutralising antibody data against Delta variant was able to be collected in this study.…”

“…This spike protein ECD antigen has been previously been shown to be immunogenic, protective, and safe in mice and ferrets in an Australian-developed vaccine called COVAX-19/SpikoGen [30] that has successfully passed phase III clinical trials and in October 2021 received emergency use authorization from the Iranian FDA [24]. This spike protein ECD formulated with an SWE adjuvant (NARUVAX-C19 vaccine) provided complete protection of Syrian hamsters against SARS-CoV-2 infection and prevented transmission to naïve animals placed in the same cage as the challenged animals [22].…”

“…In this study, we evaluated the safety, immunogenicity, and protective e cacy in juvenile cats of a recombinant spike protein vaccine formulated with either alum or Sepivac SWE™ adjuvant. This was based on our experience developing a human vaccine against COVID-19 (called NARUVAX-C19) [22], based on recombinant spike protein formulated with a nanoemulsion oil (SWE) adjuvant that in hamster studies provided complete protection and blocked virus transmission to naïve contact animals. This was the rst study to test the safety, immunogenicity, and protective e cacy in juvenile cats of our recombinant spike protein vaccine against COVID-19.…”

Application of Baculovirus Expression Vector system (BEV) for COVID-19 diagnostics and therapeutics: a review

“…It was reported that the spike protein vaccine with Sepivac SWE ™ , a nanoemulsion oil (SWE) adjuvant, provided better protection to the challenged animals compared to the RBD vaccine using the same adjuvant [65]. Besides, other adjuvants, such as Advax-SM, were also found to be effective for protection against SARS-CoV-2 [66].…”