Unrecognized diversity of mammalian orthoreoviruses in North American bats

Bats have recently been identified as potential reservoir hosts for mammalian orthoreoviruses (MRVs) throughout Europe and China. Here we present the first evolutionary and biological characterization of bat-borne MRVs in North America, including phylogenomic analysis, in vitro relative infectivity in bat and other mammalian cell cultures, host cell receptor specificity, and epifluorescence microscopy of viral factory formation. Through genetic and phylogenetic comparisons, we show that two divergent MRV serotype 2 (T2) strains – isolated from a silver-haired bat (Lasionycteris noctivagans) and a big brown bat (Eptesicus fuscus) from Pennsylvania, USA – provide an evolutionary link to an MRV strain (T2W) recovered from an 8-week-old infant who died in Winnipeg, Manitoba, Canada in 1997. Although these findings suggest North American bats may represent a previously unrecognized source for the cross-species transmission of MRVs to other animals, including humans, the ecology and epidemiology of MRVs in wildlife remain enigmatic.