UWEC CERCA 2026

Viral RNA sensing by human RIG-I-like Receptors (RLRs) is a key innate immune function in all cells. Activation of the RLR MDA5 by viral double-stranded RNA (dsRNA) is coupled with ATP hydrolysis and leads to the expression of genes encoding Type I Interferons (IFNs). In response, viral genomes have evolved to encode proteins that inhibit or weaken the Type I IFN response pathway via inhibition of RLR function. Here we aim to identify whether Nodamura virus protein B2 (NoV-B2), a viral dsRNA-binding protein, inhibits MDA5 in vitro. Human MDA5 and NoV-B2 were expressed exogenously in E. coli and purified by affinity and ion exchange chromatography. The RNA-dependent ATPase activity of MDA5 was measured in vitro by the colorimetric Malachite Green Phosphate Assay using poly(I:C) as a mimic of viral dsRNA. We then assayed this activity with NoV-B2 present to measure inhibition in vitro. Future directions for this project include: (1) investigating the mechanism of inhibition using a mutant NoV-B2 that cannot bind dsRNA, and (2) testing other viral proteins that may inhibit MDA5. These experiments help elucidate one of the mechanisms of inhibition of an immune response during viral infection.