VCP and viral infectious disease: However, significant reductions in viral RNA levels were observed in cells treated with inhibitors from pretreatment to 4 hpi (group 4), in which viral RNA levels were reduced by 79–82% and 92–96% for HCoV-229E and HCoV-OC43 infection, respectively, suggesting that p97 is essential for HCoV uncoating but may not be important for early stages of viral infection such as receptor binding and entry (Figure 3D).