Additionally, the PiT1 and PiT2 receptors are influenced by other host-specific factors, such as the FeLIX protein, which is necessary for the interaction of FeLV-T with PiT1 (58, 59), or an unknown hamster protein factor, which inhibits virus infection via the PiT1 or PiT2 receptors (60). Here, SLC20A1 is linked to viral infectious disease.