Induction of host defence responses by Drosophila C virus.

Insect responses that are specific for virus infection have been investigated using the genetically tractable Drosophila melanogaster. Most studies focus on interactions with Drosophila C virus (DCV), which is a member of the family Dicistroviridae. DCV is a non-enveloped, T=3 icosahedral virus with a positive-sense RNA genome. It was demonstrated recently that several genes controlled by the Jak-STAT pathway are specifically upregulated upon DCV infection. To investigate the virus factors that induce these responses, we used the Jak-STAT regulated genes as reporter genes. Challenge of flies with non-infectious DCV particles or double-stranded RNA did not stimulate significant upregulation of the antiviral response genes. In addition, there was no difference in reporter gene upregulation between Drosophila challenged with three different strains of DCV. This suggests that upregulation of these Drosophila genes may require virus replication and may involve the non-structural proteins of DCV.