The antiviral efficiency of Ag NPs has been demonstrated in a variety of viruses, including HIV-1,157 monkeypox virus,158 bacteriophages UZ1 and MS2,159,160 murine norovirus MNV1,159,160 HSV,161 HBV,162 and, recently, in porcine epidemic diarrhea virus (PEDV).163Antiviral properties of Ag NPs arise from three different mechanisms.