Thread by @NavroopSingh_

Th1 skewed immune response of whole virion inactivated SARS CoV 2 vaccine and its safety evaluation in this case its BBV152 i.e. COVAXIN (Study done in November 2020 & published in April 2021)- sciencedirect.com/science/articl…

We report the development and evaluation of safety and immunogenicity of a whole virion inactivated (WVI) SARS-CoV-2 vaccine (BBV152), adjuvanted with aluminum hydroxide gel (Algel), or TLR7/8 agonist chemisorbed Algel.

We used a well-characterized SARS-CoV-2 strain and an established Vero cell platform to produce large-scale GMP-grade highly purified inactivated antigen.

Immunogenicity and safety were determined at two antigen concentrations (3μg and 6μg), with two different adjuvants, in mice, rats, and rabbits.

Our results show that BBV152 vaccine formulations generated significantly high antigen-binding and neutralizing antibody titers (NAb), at both concentrations, in all three species with excellent safety profiles.

Further, in our preclinical studies, we demonstrated that all the three inactivated whole-virion SARS-CoV-2 vaccine candidates showed 100% seroconversion with high titers of antigen binding and neutralizing antibody responses.

Further, the adjuvanted IMDG formulation (BBV152B) showed more than 10 times higher antibody response, compared with antigen-alone (Figure 2C), thus Algel-IMDG formulation providing dose-sparing effect

Although major research is focused on spike as the target protein for SARS CoV-2 vaccine development, there is some attention being paid toward nucleocapsid protein as a target protein, due its 90% amino acid homology and stability with fewer mutations over time.

In conclusion, we believe that the ability to induce Th1-skewed immune response and the presence of conserved S and N protein in inactivated vaccine candidate formulated in Algel-IMDG would help to combat other SARS CoV-2 variants.

In our findings, we also observed high binding titers with a 100% seroconversion toward S1, RBD, and N protein.

Further, high neutralization titers and protective effectiveness of COVAXIN in hamster and non-human primate models might be attributed toward the structural integrity of the inactivated whole-virion vaccine composed of target proteins, both spike and N proteins.