ERVW-1 and viral infectious disease: The results showed that MDTF-fePit1 cells were permissive to enFeLV Env-pseudotyped virus infection of clone1 E345G, clone2, clone3, and AGTT, whereas MDTF-fePit2 cells were not infected with any of the enFeLV Env-pseudotyped viruses (Fig. 2D).