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Measuring Attachment and Internalization of Influenza A Virus in A549 Cells by Flow Cytometry
Published on: November 4, 2015
Hemagglutinin of influenza A virus binds specifically to cell surface nucleolin and plays a role in virus
Che-Man Chan1, Hin Chu1, Anna Jinxia Zhang1
1State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong, Hong Kong, China; Department of Microbiology, The University of Hong Kong, Hong Kong, China; Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong, China.
Abstract:
The hemagglutinin (HA) protein of influenza A virus initiates cell entry by binding to sialic acids on target cells. In the current study, we demonstrated that in addition to sialic acids, influenza A/Puerto Rico/8/34 H1N1 (PR8) virus HA specifically binds to cell surface nucleolin (NCL). The interaction between HA and NCL was initially revealed with virus overlay protein binding assay (VOPBA) and subsequently verified with co-immunoprecipitation. Importantly, inhibiting cell surface NCL with NCL antibody, blocking PR8 viruses with purified NCL protein, or depleting endogenous NCL with siRNA all substantially reduced influenza virus internalization. We further demonstrated that NCL was a conserved cellular factor required for the entry of multiple influenza A viruses, including H1N1, H3N2, H5N1, and H7N9. Overall, our findings identified a novel role of NCL in influenza virus life cycle and established NCL as one of the host cell surface proteins for the entry of influenza A virus.
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