1Doctoral Program of Biotechnology, Postgraduate Program, Universitas Jember, Jember, 68121, Indonesia
2Department of Biology Education, University of Jember, Jember, 68121, Indonesia
3Department of Agricultural Product Technology, Universitas Jember, Jember, 68121, Indonesia
4Internal Diseases Department, Dr. Soebandi Hospital, Jember, 68118, Indonesia
5Department Biology, Institut Pertanian Bogor, Bogor, 16680, Indonesia
6Department of Biology, Universitas Lampung, Lampung, 35145, Indonesia
This study aimed to explore immune responses and analyze of leukocyte cells induced by the recombinant spike protein with epitope sequences FKNHTSPDV obtained from the Indonesian SARS-CoV-2 isolate. The recombinant spike protein is synthesized by PT. Genetic Science Indonesia with a purity of 95% before being injected subcutaneously into Wistar rats on days 1, 14, and 28. Blood sampling was done before mice had injections at week 0 and mice that had undergone 3 injections or in the sixth week to obtaining an overview of leukocyte cells. Sera were harvested 14 days after each injection to determine the titers of IgG, IgM and CD4+ cells using ELISA. The results revealed that the IgG titers and CD4+ cell concentrations were found to increase after injection. Statistical test results showed meaningful differences between the control and treatment groups for IgG and CD4+ cells (p=0.003 and p=0.001 respectively). The average number of leukocytes in the three treatments was not significantly different. Conclusively, recombinant spike proteins with epitopal sequences of FKNHTSPDV isolates of Indonesian SARS-CoV-2 not only can induce humoral and cellular immune responses, and also has no impact on increasing leucocytes. It is indicated that the recombinant spike protein is feasible as a COVID-19 vaccine candidate.
SARS-CoV-2, Recombinant protein, Immune response, Indonesia, Leucocytes
