Interestingly, the infectivity of the three serotypes in double-KO Caco-2 cells was below the detection limit of our infection assay (of about 102 ffu/ml) (Fig 1B), strongly suggesting that both FcRn and DPP4 are necessary and sufficient for classical HAstV infection, at least in Caco-2 cells. The gene discussed is FCGRT; the disease is infection.