The origins and potential cross-species transmission of paramyxoviruses and other RNA viruses between native snakes and invasive Burmese pythons in the Florida Everglades

Although the evolution, molecular biology, and pathogenesis of numerous disease-causing animal paramyxoviruses have been examined extensively, studies on reptilian ferlaviruses-which have been responsible for large-scale mortality events in snakes in managed settings for decades-have lagged significantly. Herein, we document the first recognized ferlavirus disease outbreak in free-ranging snakes and provide new insights on the ferlavirus-specific U protein and reptilian host range that make these viruses unique among the paramyxoviruses. In searching for the potential source of ferlaviruses in nature, we discovered other novel RNA viruses in Burmese pythons, an invasive constrictor species introduced into the Everglades. In addition to extending the known diversity of reptilian viruses, these findings provide new fundamental insights into mammalian virus evolution and highlight the potential dangers of the cross-species transmission of such viruses into native snakes and other wildlife.