Protein vaccine NVX-CoV2373 elicits functional T cell immunity

Abstract

The SARS-CoV-2 vaccine NVX-CoV2373 is a protein-based vaccine that might circumvent the difficulties in distributing mRNA vaccines to regions with limited access to cold-chain and refrigeration. However, the NVX-CoV2373–induced T cell and antibody responses remain poorly understood. In this issue of the JCI , Moderbacher et al. characterized SARS-CoV-2–specific CD4 + and CD8 + T cell responses elicited by one or two doses of NVX-CoV2373 in individuals enrolled in a phase I/IIa trial. Substantially increased spike-specific CD4 + and T follicular helper cells were found after the first or second vaccine dose, with some individuals developing a modest spike-specific CD8 + T cell response. Correlation analysis revealed an association between spike-specific CD4 + T cells and neutralizing antibody titers. Notably, preexisting T cell immunity showed negligible effects on NVX-CoV2373–induced T cell responses. These findings indicate that the protein-based vaccine NVX-CoV2373 induces robust T cell immunity capable of recognizing SARS-CoV-2 antigens and supporting humoral immune responses.

Longitudinal analysis of memory T follicular helper cells and antibody response following CoronaVac vaccination

“…SARS-CoV-2 mRNA vaccines can induce robust antigen-specific TFH responses in both peripheral blood and lymph nodes and maintained for 6 months (14,15,39). Similarly, our study found that CoronaVac vaccine efficiently elicited spike-specific, IFN-γ/IL-2 producing CD4 + T cells and cTFH cells necessary for the anti-viral and antibody response (26,(40)(41)(42). And the expanded spike-specific cTFH cells were biased to the proinflammatory cTFH17 subsets post the 2 nd and 3 rd dose of CoronaVac, which was also found after SARS-CoV-2 infection (43,44).…”

“…Sequential COVID-19 vaccinations with diverse vaccine platforms can effectively induce robust adaptive immune responses that provide protection against severe complications caused by SARS-CoV-2 and its subvariants (26,40,49). While the magnitudes of spikespecific and variant-specific antibody and T cell responses are mostly comparable between BNT162b2 and mRNA-1273, and higher than those induced by Ad26.COV2.S and NVX-CoV2373, direct comparison studies on comprehensive clinical and immunological parameters between inactivated COVID-19 vaccines such as CoronaVac and other vaccine platforms are limited (50)(51)(52).…”

Longitudinal analysis of memory Tfh cells and antibody response following CoronaVac vaccination

“…SARS-CoV-2 mRNA vaccines can induce robust antigen-specific Tfh responses in both peripheral blood and lymph nodes that are maintained for 6 months ( 8 , 14 , 15 ). Similarly, our study found that CoronaVac vaccine efficiently elicited spike-specific IFN-γ/IL-2–producing CD4 + T cells and cTfh cells necessary for the antiviral and antibody response ( 24 , 37 – 39 ). The expanded spike-specific cTfh cells were biased toward the proinflammatory cTfh17 subsets after the second and third dose of CoronaVac, which was also found after SARS-CoV-2 infection ( 40 , 41 ).…”

“…Sequential COVID-19 vaccinations with diverse vaccine platforms can effectively induce robust adaptive immune responses that provide protection against severe complications caused by SARS-CoV-2 and its subvariants (24,37,47). Although the magnitudes of spike-specific and variant-specific antibody and T cell responses are mostly comparable between BNT162b2 and mRNA-1273, and higher than those induced by Ad26.COV2.S and NVX-CoV2373, direct comparison studies on comprehensive clinical and immunological parameters between inactivated COVID-19 vaccines such as CoronaVac and other vaccine platforms are limited (48)(49)(50).…”