Influenza A Virus Induces Autophagy by Its Hemagglutinin Binding to Cell Surface Heat Shock Protein 90AA1.

Xingbo Wang,Jing Lei,Yan Yan,Jiyong Zhou,Tuyuan Zheng,Yina Zhang,Lulu Lin,Xiran Peng,Boli Hu

doi:10.3389/fmicb.2020.566348

Xingbo Wang, Jing Lei + Show 7 more

Open Access

https://doi.org/10.3389/fmicb.2020.566348

Copy DOI

Abstract

Autophagy can be utilized by the influenza A virus (IAV) to facilitate its replication. However, whether autophagy is induced at the stage of IAV entry is still unclear. Here, we report that IAV induces autophagy by hemagglutinin (HA) binding to heat shock protein 90AA1 (HSP90AA1) distributed on the cell surface. Virus overlay protein binding assay and pull-down assay indicated that IAV HA bound directly to cell surface HSP90AA1. Knockdown of HSP90AA1 weakened H1N1 infection. Incubation of IAV viral particles with recombinant HSP90AA1 or prior blockade of A549 cells with an anti-HSP90AA1 antibody could inhibit attachment of IAV. Moreover, we found that recombinant HA1 protein binding to cell surface HSP90AA1 was sufficient to induce autophagy through the AKT-MTOR pathway. Our study reveals that the HSP90AA1 on cell surface participates in IAV entry by directing binding to the HA1 subunit of IAV and subsequently induces autophagy.

Highlights

Influenza A virus (IAV), a negative-sense single-stranded RNA virus, belongs to the Orthomyxoviridae family (Peiris et al, 2007)
To determine whether IAV binds to cell surface HSP90AA1, HSP90AA1 was immunoprecipitated from membrane components by using an anti-HSP90AA1 antibody, the membrane proteins, or immunoprecipitation (IP) samples were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transferred to nitrocellulose (NC) membrane, virus overlay protein blot assay was carried out
We demonstrated that HSP90AA1 could be extracted from the cell membrane and reacted with IAV

Summary

Introduction

Influenza A virus (IAV), a negative-sense single-stranded RNA virus, belongs to the Orthomyxoviridae family (Peiris et al, 2007). Influenza A virus causes annual seasonal epidemics and leads to great economic losses worldwide (Zhou et al, 2009). This virus attaches to the terminal sialic acid (SA), which has long been recognized as the primary receptor on the cell surface (Sauter et al, 1992; Fukuzawa et al, 2011), and through the viral hemagglutinin (HA) glycoprotein and initiates the entry process via multiple endocytic pathways (Hers, 1966; Skehel and Wiley, 2000). The HA1 subdomain forms the globular head of this structure and is responsible for the binding of IAV to SAs on the host cell membrane and subsequently initiates virus entry by virus-cell adsorption and endocytosis (Yang et al, 2013). Whether IAV utilizes other putative receptors or certain receptor components to facilitate entry is still largely unknown

Methods

Results

Conclusion