A Drosophila model for genetic analysis of influenza viral/host interactions.

Influenza viruses impose a constant threat to vertebrates susceptible to this family of viruses. We have developed a new tool to study virus-host interactions that play key roles in viral replication and to help identify novel anti-influenza drug targets. Via the UAS/Gal4 system we ectopically expressed the influenza virus M2 gene in Drosophila melanogaster and generated dose-sensitive phenotypes in the eye and wing. We have confirmed that the M2 proton channel is properly targeted to cell membranes in Drosophila tissues and functions as a proton channel by altering intracellular pH. As part of the efficacy for potential anti-influenza drug screens, we have also demonstrated that the anti-influenza drug amantadine, which targets the M2 proton channel, suppressed the UAS-M2 mutant phenotype when fed to larvae. In a candidate gene screen we identified mutations in components of the vacuolar V1V0 ATPase that modify the UAS-M2 phenotype. Importantly, in this study we demonstrate that Drosophila genetic interactions translate directly to physiological requirements of the influenza A virus for these components in mammalian cells. Overexpressing specific V1 subunits altered the replication capacity of influenza virus in cell culture and suggests that drugs targeting the enzyme complex via these subunits may be useful in anti-influenza drug therapies. Moreover, this study adds credence to the idea of using the M2 "flu fly" to identify new and previously unconsidered cellular genes as potential drug targets and to provide insight into basic mechanisms of influenza virus biology.