Immunogenicity of vaccine encoding spike protein against Middle East respiratory syndrome coronavirus in mammalian model.

The Middle East respiratory syndrome coronavirus (MERS-CoV) represents a major threat to human health worldwide. No licensed MERS-CoV vaccines or therapeutics were developed. So, the aim of the current study is the generation and immunological evaluation of DNA vaccine candidate against MERS-CoV. The spike gene was selected to generate the DNA vaccine, which encodes the spike protein of coronaviruses that plays a pivotal role in viral entry into host cells and serves as a primary target for host immune responses. Moreover, the antibody responses post-immunization with spike-DNA fragment and inactivated coronaviruses vaccines was explored, using a microneutralization assay with severe acute respiratory syndrome (SARS-CoV-2), and the log2 antibody titers at different time points (0, 2, 4, 6, and 8 weeks) post-vaccination was measured. The inactivated MERS-CoV and pCDNA3.1-S-MERS-CoV vaccines maintained steady log2 antibody titers, showing no specific response to SARS-CoV-2 in the control group (PBS). Microneutralization against MERS-CoV showed no significant antibody titers for Inactivated SARS-CoV-2, suggesting no cross-reactivity. Sustained antibody titers for Inactivated MERS-CoV indicate vaccine-induced stability. This study sheds light on antibody responses induced by these vaccines against MERS-CoV. These insights are crucial for optimizing vaccine strategies, particularly in the context of the evolving MERS-CoV pandemic.