Identifying spike correlates driving merbecovirus pathogenesis

Abstract The coronavirus spike has two major functions in the virus life cycle: receptor binding/attachment and entry/fusion via proteolytic activation. While most CoV emergence research focuses on receptor binding capacity, we believe that changes in proteolytic activation of spike is critical for CoV infection. Here, we argue that motifs in the S1/S2 loop of MERS-CoV and merbecovirus spike play a critical role in infection and pathogenesis. Variation in the S1/S2 loop impacts the spike cleavage efficiency, spike processing on virions, and endosomal versus cell surface entry route. In turn, mutations that impact any of these variables will alter viral infection, pathogenesis, and transmission. In this proposal, we utilize a combination of reverse genetics, in vitro, and in vivo systems to establish which elements contribute to CoV infection, disease, and pathogenesis. These insights will inform surveillance of zoonotic strains, provide insights to infection mechanisms, and provide avenues to mitigate future CoV emergence events.