Abstract: Transgenic non-human animals are described comprising a transgene for a species-specific pathogen and transgene(s) for at least one receptor restricting infection of the pathogen to the host species. Also described is a method for creating the transgenic non-human animal of this invention and a method for screening an agent for the ability to inhibit infection by a species-specific virus using said transgenic non-human animal. The transgenic animal of this invention has a sustained productive viral infection and does not develop a virus-specific immune response, thereby resulting in an extremely useful self-contained system to investigate the factors modulating in vivo replication of human pathogens, the pathophysiological effect of pathogen replication and production, and the effectiveness of novel therapies and vaccines modifying or inhibiting the course of pathogenesis.