MHV
Here we report that additional coronavirus superfamily members, including lineage A betacoronaviruses and toroviruses infecting both humans and animals, encode 2',5'-PDEs capable of antagonizing RNase L. We used a chimeric MHV system (MHV<sup>Mut</sup>) in which exogenous PDEs were expressed from an MHV backbone lacking the gene for a functional NS2 protein, the endogenous RNase L antagonist.