INFLUENZA A VIRUS NUCLEOPROTEIN REQUIRES THE HUMAN POLYADENYLATE BINDING PROTEIN (PABPC1) FOR SUCCESSFUL VIRUS REPLICATION

Abstract

Intro: Influenza A is an emerging virus that causes serious respiratory disease. IAVs rapidly evolve, resulting in novel strains which may be unaccounted for in current available treatments. The implications of which can lead to the death of vulnerable patients. IAV replication is highly dependent on human cellular machinery which is not fully understood till date. Investigating the structurally conserved IAV nucleoprotein (NP) and its involvement with human PABPC1 (a translation facilitator protein) may allow for the identification of a novel antiviral target. Methods: LC-MS/MS screening indicated NP-PABPC1 interaction. Interaction studies were validated using co-immunoprecipitation assay. Amino acid interacting residues were also predicted using insilico methods. Cellular fractionation, immunofluorescence and confocal microscopy were performed for cellular compartmentalization and co-localization of the proteins. siRNA silencing of endogenous PABPC1 was performed and plaque assay evaluation of IAV virus titer followed by western blot analysis of IAV NP protein levels were performed. Findings: A protein-protein interaction has been found in this study between both proteins. Both virus and host proteins showed co-localization in the cytoplasm of mammalian cells at multiple time points post virus infection or NP gene transfection. In addition, IAV has been found to be highly dependent on the availability of human PABPC1 in the cells to successfully replicate. The silencing of endogenous PABPC1 resulted in a significant decrease in IAV titer Conclusion: There is a clear relationship that has been deciphered between IAV NP and human PABPC1. It was found that both proteins are involved in a direct interaction and co-localize within the cytoplasm of mammalian cells at a high rate. IAV replication is disrupted when human PABPC1 is less abundant and the overall virus titer and IAV NP protein levels significantly decrease. PABPC1 can be considered as an antiviral target provided further in vivo experiments are performed to prove the effect