Prospect of Using RaTG13 Sarbecovirus As a Candidate Vaccine for COVID-19

Abstract

The development of an adept and potent countermeasure, especially a vaccine to provide active acquired immunity against the virus is essential to cease the accelerated spread of COVID-19. In this study, we attempt to justify the prospect of designing a vaccine for COVID-19 based on the genetic similarity between the SARS‐CoV‐2 and RaTG13 virus.

Various studies reveal a sequence similarity between that of SARS-COV-2 and bat RaTG13 i.e. up to 96% genetic similarity. The major differences being in the receptor-binding domain of spike protein.

In this study, the protein sequences for a set of predicted epitope sites on spike, nucleocapsid, and membrane proteins of SARS-CoV-2 strains were compared for the same sequence on the RaTG13 virus. The results indicated a high degree of similarity for the epitope sites ranging between 95-100% for both T and B cell epitopes.

Using the zoonotic strain RaTG13 virus as a vaccine could prove to have an added advantage such that the furin cleavage site present on the spike proteins of SARS-CoV-2 is absent in RaTG13 virus. This furin cleavage site is essential for the entry of the virus onto the host cell and hence vital for causing infection. Thus, its absence could add to the safety of the vaccine.

With the high degree of similarity observed for B & T cell epitope sites in SARS-CoV-2 and RaTG13 and the absence of furin cleavage sites on RaTG13 as an additional advantage, the study suggests that the zoonotic RaTG13 virus could be considered for the development of a potential vaccine for COVID-19.

Note: Conflict of Interest: The authors report no conflicts of interest.

Keywords: SARS-CoV-2, Vaccine, RaTG13, Epitopes, Immunology