The present invention relates to an antiviral drug comprising as an active ingredient a substance capable of suppressing an expression of a target gene or an activity of a protein encoded by said target gene, wherein said target gene is one or more genes having an action of retaining virus-derived nucleic acid in a host cell and selected from the group consisting of DOCK11 gene, LIPG gene, DENND2A gene, and HECW2 gene. The present invention also relates to a screening method for the antiviral drug.