Influenza A Virus Induces Autophagy By Its Hemagglutinin Binding To Cell Surface Heat Shock Protein 90AA1

Influenza A virus is the major pathogen causing human respiratory tract infection and influenza.Recognition of receptors to viral particle is critical for entry of virus and mediating extremely early signaling pathways response to virus infection,the viral membrane protein of IAV to recognize receptor is HA.It is well known sialic acid is the primary receptor of IAV,however,IAV retain the ability to infect some desialylated cells.There is still debate as to whether IAV entry into target cells requires additional host factors.HSP90AA1 is a multifunctional protein in eukaryotes,In addition to its most important function as a chaperone in cells,growing evidence indicates that HSP90AA1 serves as a component of virus receptor complex to facilitate entry of virus.However,whether influenza A virus is recognized by cell surface HSP90AA1 is still unclear.In present study,virus overlay protein binding assay and confocalassay indicated that H1N1 HA bound to cell surface HSP90AA1.Then CoIP assay and pull down assay identified the interaction between HA1 that contain receptor binding site of HA and HSP90AA1 deeply.Based on these,we guess HSP90AA1 may play a role in virus entry.Incubation of H1N1 viral particles with recombinant HSP90AA1 or prior blockade of A549 cells with antiHSP90AA1 antibody could inhibit attachment of H1N1,westrn blot and IFA assay detected the decrease of NP level,Hemagglutination assay found HSP90AA1 weakened H1N1 infection.All of these results suggesting HSP90AA1 function during virus entry,however,it is unclear HSP90AA1 being as a dependant receptor or a factor assist other receptor.Autophagy can be utilized by influenza A virus to facilitate its replication.However,whether autophagy is induced at the stage of IAV entry is still unclear.Virus can interact with receptors which exit in the cell membrane,and the AKT-MTOR signal pathway can induce autophagy,so we detected the affection of AKT-MTOR and autophagy during recombinant protein HA1 treatment.We used the purificated protein of HA1 incubated with cells at 4?,results showed HA1 can decrease AKT-MTOR phosphorylation,and the indicator of autophagy--P62 decrease,LC3-II increase significantly.The LC3-II increased more on the condition of CQ treatment.Furthermore,the autophagy was induced by AKT-MTOR pathway,which was inhabit owe to the binding of AKT and HSP90AA1 was weaken due to the binding of HA1 and HSP90AA1.Thus,this study identified on the process of IAV entry,the membrane HSP90AA1 serve as an receptor to recognize IAV viral protein HA1 which contain the receptor binding site,then induce autophagy by inactivation of AKT/mTOR pathway.The new molecular was found as a potential IAV receptor,which could be a new idea to develop the antiviral durg.