The novel coronavirus SARS‐CoV‐2: From a zoonotic infection to coronavirus disease 2019

Abstract

Objective The novel coronavirus, SARS‐CoV‐2 is an international public health emergency. Until now, the intermediate host and mechanisms of interspecies jump of this virus are unknown. Methods Phylogenetic analysis of all available bat coronavirus (CoV) complete genomes was performed in order to analyze the relationships between bat CoV and SARS‐CoV‐2. In order to suggest a possible intermediate host, another phylogenetic reconstruction of CoV genomes obtained from animals which were hypothetically commercialized in the Chinese markets was also carried out. Moreover, mutation analysis was executed to suggest genomic regions which may have permitted the adaptation of SARS‐CoV‐2 to the human host. Results The phylogenetic analysis demonstrated that SARS‐CoV‐2 formed a cluster with the bat CoV isolate RaTG13. Possible CoV interspecies jumps among bat isolates were also observed. The phylogenetic tree reconstructed from CoV strains belonging to different animals demonstrated that SARS‐CoV‐2, bat RaTG13 and pangolin CoV genomes formed a monophyletic cluster, demonstrating that pangolins may be suggested as SARS‐CoV‐2 intermediate hosts. Three AA substitutions localized in the S1 portion of the S gene were observed, some of which have been correlated to structural modifications of the S protein which may facilitate SARS‐CoV‐2 tropism to human cells. Conclusions Our analysis shows the tight relationship between SARS‐CoV‐2 and bat SARS‐like strains. It also hypothesizes that pangolins might have been possible intermediate hosts of the infection. Some of the observed AA substitutions in the S binding protein may serve as possible adaptation mutations in humans but more studies are needed to elucidate their function.