A new study reports the isolation of a novel coronavirus (CoV) from Chinese horseshoe bats, which is more closely related to severe acute respiratory syndrome coronavirus (SARS-CoV) than any previously identified bat CoV, providing strong evidence that SARS-CoV might have originated in bats. Whole-genome sequencing of the novel CoV revealed that it shares 95% sequence identity with human SARS-CoV, with the receptor-binding domain (RBD) in the spike protein from both viruses showing an identical amino acid sequence. The RBD of human SARS-CoV uses the cellular receptor angiotensin-converting enzyme 2 (ACE2) for cell entry, and infectivity assays confirmed that the novel CoV also uses human ACE2 for cell entry, suggesting that it might be capable of directly infecting humans. Furthermore, preliminary in vitro data suggest that the new virus has broad species tropism.