Ability of Orally Administered IFN-α-Containing Transgenic Potato Extracts to Inhibit Listeria monocytogenes Infection

Type I interferons (IFN-α/β) were originally thought to be antiviral cytokines, but it has recently been reported that they also play an important role in potentiating innate and adaptive immune responses. Moreover, several studies have shown that the oral administration of type I IFN ameliorates various biologic activities. Here, we studied the ability of orally administered IFN-α to protect mice from systemic Listeria monocytogenes infection. Daily oral administration of purified natural IFN-α at a concentration of 1000 international units (IU)/20 µl reduced the bacterial burden in infected organs. We also examined the protective effect of IFN-α expressed in transgenic potato plants. A much lower concentration of IFN-α (20 IU/ 20 µl) in the plant extracts was almost as protective as much higher concentrations of purified natural IFN-α. Our observations indicate that transgenic cytokine-expressing plants can be used prophylactically as edible pharmaceuticals to enhance systemic defense responses in human...