The Beachboard lab is interested in host-pathogen interactions with a focus on Coronaviruses. We use the model coronavirus mouse hepatitis virus (MHV) to study viral inhibition of antiviral innate immunity. Viruses have three main mechanism to evade antiviral innate immunity, 1) replication within membranes to prevent cytosolic detection of viral nucleic acids; 2) viral proteases cleave host innate immune proteins; and 3) sequestration of innate immune proteins. We focus on viral proteases cleavage of innate immune proteins. Coronaviruses encode 2-3 viral proteases. PLP1/2 are encoded within the non-structural protein 3 (nsp3) and depending on the viral strain, there may only be one. The third protease domain is encoded by nsp5 and is the focus of our work.