It is provided an anti-viral fusion protein comprising the structure of X-Y-Z, wherein X is a full length Ricin A chain (RTA) or a variant thereof, Y is absent or a linker and Z is a full length Pokeweed antiviral proteins (PAP) or a variant thereof. Particularly, it is provided an optimized protein ricin A chain mutant-Pokeweed antiviral protein isoform 1 from leaves (RTAM-PAP1).