<div>Researchers have found a 96% similarity in nucleotide sequence between bat coronavirus (RaTG13), isolated from Rhinolophus affinis bats in China in 2013, and SARS-CoV-2 and ~97% amino acid similarity with the Spike (S) protein. This S protein performs two essential roles, i.e., mediates receptor-binding and membrane fusion. Hence, spike protein is regarded as a key coronavirus determinant of host tropism.</div>