Inactivated SARS-CoV-2 vaccine candidate immunization on non-human primate animal model: B-cell and T-cell responses immune evaluation

BACKGROUND: SARS-CoV-2 vaccine was proven to be an effective and efficient measure for mitigating pandemic. COVID-19 infection and mortality subsided along with the increaseing COVID-19 vaccination coverage. Vaccine and health resource equity are predominant factors in COVID-19 pandemic management. Vaccine development for Indonesia, aims to ensure a sustainable pandemic control and steady national stability restoration. A decent vaccine must induce immunity against COVID-19 with minimum adverse reaction. Immunogenicity and ability to induce neutralizing antibody evaluation needs to be performed as part of the SARS-CoV-2 inactivated vaccine development from East Java, Indonesia isolate (Vaksin Merah Putih-INAVAC). OBJECTIVE: This research demonstrated INAVAC performance in inducing the production neutralizing antibody along with its effects on CD4(+) and CD8(+) cells response in Macaca fascicularis (non-human primate). METHODS: Two dosages of 3 μg and 5 μg were tested, compared to sham (NaCl 0.9%) in 10 Macaca fascicularis (2 injection intramuscular with 14 days interval). All animals were monitored daily for clinical signs. Nasopharyngeal samples were analyzed using qRT-PCR while the serum were tested using ELISA and neutralization assay, whereas PBMCs were flowcytrometrically analyzed to measure CD4(+) and CD8(+) population. RESULTS: It is observed that both vaccine doses could stimulate relatively similar immune response and neutralizing antibody (end GMT post challenge = 905,1), whereas higher CD8(+) cells response were reported in the 5 μg group after the 3rd day post-challenge. The dose of vaccine that produce adequate immune cell stimulation with neutralizing antibody induction can be adopted to clinical study, as favorable result of these parameters could predict minimum adverse reaction from inflammation response with balanced immune response. CONCLUSIONS: Therefore, it is concluded that Vaksin Merah Putih-INAVAC with 3 μg dose showed a favorable potential to be developed and tested as human vaccine.