Genome-wide RNAi screen identifies SEC61A and VCP as conserved regulators of Sindbis virus entry

Alphaviruses are a large class of insect-borne human pathogens and little is known about the host-factor requirements for infection. To identify such factors, we performed a genome-wide RNAi screen using model Drosophila cells and validated 94 genes that impacted infection of Sindbis virus (SINV), the prototypical alphavirus. We identified a conserved role for SEC61A and valosin-containing protein (VCP) in facilitating SINV entry in insects and mammals. SEC61A and VCP selectively regulate trafficking of the entry receptor NRAMP2, and loss or pharmacological inhibition of these proteins leads to altered NRAMP2 trafficking to lysosomal compartments and proteolytic digestion within lysosomes. NRAMP2 is the major iron transporter in cells, and loss of NRAMP2 attenuates intracellular iron transport. Thus, this study reveals genes and pathways involved in both infection and iron homeostasis that may serve as targets for antiviral therapeutics or for iron-imbalance disorders.