Arthropod-borne viruses (arboviruses) include numerous human and animal pathogens that are important global health threats. Flaviviruses are arboviruses belonging to the Flaviviridae family. They include neurotropic viruses such as West Nile (WNV), Japanese encephalitis (JEV) and the emerging Zika (ZIKV) viruses, as well as viruses responsible for hemorrhagic fever such as the 4 serotypes of dengue (DV) viruses. Like any other obligate intracellular pathogens, they use hijacking of cellular protein functions as a strategy for sustaining their life cycle.
Many cellular proteins display globular motifs known as PDZ motifs that have been shown to interact with PDZ Binding Motifs (PBM) identified on many viral proteins. Thus cellular PDZ-containing proteins are common targets during viral infection. PDZ/PBM interactions play a central role in cell signaling by mediating protein-protein interactions in complex networks. Moreover, during infection, the viral proteins by binding to the PDZ of the host targets not only compete with the endogenous ligands but also affect the catalytic activity of signaling proteins. Functional perturbations of cellular processes due to interactions between viral PBMs and cellular PDZ-containing proteins may improve the virus life cycle in its host and dissemination to new hosts. Therefore targeting the PBM-PDZ interface could potentially lead to novel antiviral therapies.
We aim at characterizing the role of PDZ/PBM interactions in the life cycle of different flaviviruses, namely WNV, JEV, DV and ZIKV viruses. Our main objectives in this project are to:
– Test putative PBM sequences within NS5 and NS1 proteins of WNV and JEV against a full library of human PDZ domains (PDZome) by high-throughput interactomic studies (Hold-Up Assay) and re-examine the DV NS5 PBM and potential DV NS1 PBM against the PDZome
– Validate the ability of full-length WNV and JEV NS1 and NS5 proteins to interact with the PDZome, and explore and identify potential PBMs on full-length DV and ZIKV NS1 and NS5 proteins by NanoLuciferase Protein Complementation Assay (NPCA)
– Decipher the role of PBM sequences in the replication of WNV, JEV, DV and ZIKV by testing wt and mutated constructs containing the replicative region of the virus genomes (replicons) and/or full-length genomes (infectious clones)
– Evaluate the effect of mutation(s) in PBM sequence(s) of WNV and JEV on pathogenesis in an animal model (mouse)
This ongoing work is performed in collaboration with N. Wolff and Y. Jacob’s team on the campus.