Comparative phylogenetic analysis of SARS-CoV-2 spike protein-possibility effect on virus spillover.

Coronavirus disease 2019 has developed into a dramatic pandemic with tremendous global impact. The receptor-binding motif (RBM) region of the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), binds to host angiotensin-converting enzyme 2 (ACE2) receptors for infection. As ACE2 receptors are highly conserved within vertebrate species, SARS-CoV-2 can infect significant animal species as well as human populations. An analysis of SARS-CoV-2 genotypes isolated from human and significant animal species was conducted to compare and identify mutation and adaptation patterns across different animal species. The phylogenetic data revealed seven distinct phylogenetic clades with no significant relationship between the clades and geographical locations. A high rate of variation within SARS-CoV-2 mink isolates implies that mink populations were infected before human populations. Positions of most single-nucleotide polymorphisms (SNPs) within the spike (S) protein of SARS-CoV-2 genotypes from the different hosts are mostly accumulated in the RBM region and highlight the pronounced accumulation of variants with mutations in the RBM region in comparison with other variants. These SNPs play a crucial role in viral transmission and pathogenicity and are keys in identifying other animal species as potential intermediate hosts of SARS-CoV-2. The possible roles in the emergence of new viral strains and the possible implications of these changes, in compromising vaccine effectiveness, deserve urgent considerations.