Host-pathogen interactions in Drosophila PERSPECTIVE inhibition of autophagy ( Fig. 2A) . Akt activation is also attenuated by expression of the SARS-Coronovirus Membrane protein in flies, which in this case results in increased apoptosis (Chan et al., 2007) . In another study, host factors required for the HIV accessory protein Nef to downregulate expression of the human CD4 protein were identified by RNAi screening in Drosophila S2 cells expressing human CD4. These factors included components of the clathrinassociated AP2 complex, which was then validated as an essential cellular component mediating a similar Nef-CD4 interaction in human cells (Chaudhuri et al., 2007) .