A Comprehensive Classification of Coronaviruses and Inferred Cross-Host Transmissions

In this work, we present a unified and robust classification scheme for coronaviruses based on concatenated protein clusters. This subsequently allowed us to infer the apparent "horizontal gene transfer" events via reconciliation with the corresponding gene trees, which we argue can serve as a marker for cross-host transmissions. The cases of SARS-CoV, MERS-CoV, and SARS-CoV-2 are discussed. Our study provides a possible technical route to understand how coronaviruses evolve and are transmitted to humans.