Studies have shown that N protein can also mediate the small ubiquitin-like modifier (SUMO) modification of MAVS, a key factor of human natural immunity, by interacting with Ubc9, the only SUMO-conjugated enzyme, thereby preventing the activation of human innate immune response against COVID-19 [94]; Guo et al. constructed K18-hACE2 KI mice that stably express related proteins and established an infection model of RDPs. Here, MAVS is linked to infection.