Emergence of SARS-CoV-2 through Recombination and Strong Purifying Selection

Xiaojun Li; Elena E. Giorgi; Manukumar Honnayakanahalli Marichann; Brian Foley; Chuan Xiao; Xiang-peng Kong; Yue Chen; Bette Korber; Feng Gao

So far efforts have failed to find the original pathway of SARS-CoV-2 into humans by identifying a coronavirus that is nearly identical to SARS-CoV-2, as those found for SARS and MERS in civets and domestic camels respectively (12, 13) . However, if the new SARS-CoV-2 strain did not cause widespread infections in its natural or intermediate hosts, such a strain may never be identified. The close proximity of animals of different species in a wet market setting may increase the potential for cross-species spillover infections, by enabling recombination between more distant coronaviruses and the emergence of recombinants with novel phenotypes. While the direct reservoir of SARS-CoV-2 is still being sought, one thing is clear: reducing or eliminating direct human contact with wild animals is critical to preventing new coronavirus zoonosis in the future.