Studying host lipid rafts in early phases of Influenza A Virus (IAV) life cycle for the identification of Hemagglutinin interacting host raft proteins
Dileep K. Verma1, Dinesh Gupta1, Sunil K. Lal 2 1 Translational Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India; 2 School of Science, Monash University, Malaysia Binding of Influenza A Virus (IAV) to the host cell followed by entry inside host cell are rather complex events. IAV binding to the host cell requires multiple simultaneous interactions between viral hemagglutinin (HA) and its host receptor sialic acid (SIA). However, the exact mechanism to form multiple HA-SIA interactions is poorly understood. Similarly, IAV enters the host cell via multiple endocytic routes making the process even more complicated. Also, a cellular endocytic pathway regulated by lipid rafts termed 'raft-dependent endocytosis', has so far been poorly investigated for IAV host cell entry1. In this study, we observed the co-localization of IAV with host lipid rafts and cyclodextrin based host raft disruption showed significant reduction in the ability of IAV to bind the host cells. Interestingly, cyclodextrin mediated inhibition of raft-dependent endocytosis also showed significantly reduced IAV host internalization. However, exposure of cells to cyclodextrin, two hours post-IAV binding showed no such reduction. In summary, our data collectively demonstrates that host lipid rafts are selected by IAV for multivalent binding and IAV utilizes these micro-domains to exploit raft-dependent endocytosis for host internalization, a virus entry route previously unknown for IAV. Since IAV hemagglutinin (HA) is known to regulate two crucial events in IAV life cycle, receptor binding followed by endocytosis and membrane fusion; we further attempted to identify possible raft protein/s interacting with IAV HA. During our preliminary investigation, we have identified few raft proteins as potential interactors of IAV HA and their suggested functions indicate involvement in HA mediated processes. Currently, we are further validating their interactions and functional roles in IAV life cycle. Through this study, we aim to enhance the way we understand IAV host binding, entry via endocytosis and membrane fusion inside the host cell.
Edinger, T.O., M.O. Pohl, and S. Stertz, Entry of influenza A virus: host factors and antiviral targets. J Gen Virol, 2014. 95(Pt 2): p. 263-77.
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