| dc.description.abstract | Viral life cycles are facilitated by protein-protein interactions between viral proteins and the host counterparts to ensure each stage of the replication is productive. These interactions mark potential therapeutic intervention points. Interactions during flavivirus and coronavirus infections were studied using a combination of small-molecule and affinity purification-mass spectrometry approaches. Using dengue virus as a model, compounds 147 and 263 were shown to reduce propagation of flaviviruses up to 99% in a liver cell model. As opposed to traditional direct-acting antivirals, these compounds work by perturbing the function of host proteins, though the relevant proteins each molecule modifies has not yet been identified. Although they possess similarly reactive moieties, it was shown the two molecules have divergent mechanisms and modify different classes of proteins; 147 requires covalent modification of thiols, while 263 does not. Encouragingly, both compounds were effective against several serotypes of dengue virus and strains of Zika virus, highlighting the broad-spectrum potential of these host-centered therapeutics. To study the protein-protein interactions of coronaviruses, homologous proteins from up to five different coronavirus strains were expressed, and these proteins and their interactors were isolated using affinity purification. Mass spectrometry allowed for high-throughput identification of these interactors, and comparative data analysis revealed the similarities and differences in interactions between homologous coronavirus proteins from mild and severe-disease causing variants. Non-structural proteins 2 and 4 showed an enrichment in interactions with mitochondrial-associated membrane proteins. Additional biological follow-up showed the ability of non-structural protein 3 from SARS-CoV-2, the causative agent of COVID-19, to manipulate the ER unfolded protein response in a branch-specific manner. | |
