Drosophila RNAi screen identifies host genes important for influenza virus replication

Nature (On line 10.1038/nature07151)

Linhui Hao^1,2,10, Akira Sakurai^3,10,11, Tokiko Watanabe³, Ericka Sorensen¹, Chairul A. Nidom^5,6, Michael A. Newton⁴, Paul Ahlquist^1,2 & Yoshihiro Kawaoka^3,7,8,9

1. Institute for Molecular Virology, 2. Howard Hughes Medical Institute, 3. Department of Pathobiological Sciences, and, 4. Departments of Statistics and of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA 5. Faculty of Veterinary Medicine, and, 6. Collaborating Research Center-Emerging & Reemerging Infectious Diseases, Tropical Disease Centre, Airlangga University, Surabaya 60115, Indonesia 7. Division of Virology, Department of Microbiology and Immunology, and, 8. International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan 9. Division of Zoonosis, Department of Microbiology and Infectious Diseases, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan 10. These authors contributed equally to this work. 11. Present address: First Department of Forensic Science, National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa 277-0882, Japan.

All viruses rely on host cell proteins and their associated mechanisms to complete the viral life cycle. Identifying the host molecules that participate in each step of virus replication could provide valuable new targets for antiviral therapy, but this goal may take several decades to achieve with conventional forward genetic screening methods and mammalian cell cultures. Here we describe a novel genome-wide RNA interference (RNAi) screen in Drosophila that can be used to identify host genes important for influenza virus replication. After modifying influenza virus to allow infection of Drosophila cells and detection of influenza virus gene expression, we tested an RNAi library against 13,071 genes (90% of the Drosophila genome), identifying over 100 for which suppression in Drosophila cells significantly inhibited or stimulated reporter gene (Renilla luciferase) expression from an influenza-virus-derived vector. The relevance of these findings to influenza virus infection of mammalian cells is illustrated for a subset of the Drosophila genes identified; that is, for three implicated Drosophila genes, the corresponding human homologues ATP6V0D1, COX6A1 and NXF1 are shown to have key functions in the replication of H5N1 and H1N1 influenza A viruses, but not vesicular stomatitis virus or vaccinia virus, in human HEK 293 cells. Thus, we have demonstrated the feasibility of using genome-wide RNAi screens in Drosophila to identify previously unrecognized host proteins that are required for influenza virus replication. This could accelerate the development of new classes of antiviral drugs for chemoprophylaxis and treatment, which are urgently needed given the obstacles to rapid development of an effective vaccine against pandemic influenza and the probable emergence of strains resistant to available drugs.

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