Th1 skewed immune response of whole virion inactivated SARS CoV 2 vaccine and its safety evaluation

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. Product development and manufacturing process were carried out in a BSL-3 facility. Immunogenicity and safety were determined at two antigen concentrations (3 mu g and 6 mu g), 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. The inactivated vaccine formulation contains TLR7/8 agonist adjuvant-induced Th1-biased antibody responses with elevated IgG2a/IgG1 ratio and increased levels of SARS-CoV-2-specific IFN-gamma(+) CD4(+) T lymphocyte response. Our results support further development for phase I/II clinical trials in humans.

Automated summary

The study reports the development and evaluation of a whole virion inactivated COVID-19 vaccine, showing high antigen-binding and neutralizing antibody titers in mice, rats, and rabbits, with excellent safety profiles.