IFITM3 and infection: Establishing physical contact with the v‐ATPase of endosomes is critical for proper clathrin localization and is required for v‐ATPase to lower the pH in phagocytic endosomes, thus establishing an antiviral state.57 High expression of both HP‐PRRSV and AP‐PRRSV suggests that IFITM3 may help inhibit PRRSV entry and promote resistance to HP‐PRRSV infection.