An isolated and purified nucleic acid molecule that encodes a polypeptide comprising at least eight contiguous amino acids of SEQ ID NO: 3, wherein the at least eight contiguous amino acids have anti-viral activity, as well as an isolated and purified nucleic acid molecule that encodes a polypeptide comprising at least eight contiguous amino acids of SEQ ID NO: 3, wherein the at least eight contiguous amino acids have anti-viral activity, and, when the at least eight contiguous amino acids comprise amino acids 1-121 of SEQ ID NO: 3, the at least eight contiguous amino acids have been rendered glycosylation-resistant, a vector comprising such an isolated and purified nucleic acid molecule, a host cell comprising the nucleic acid molecule, optionally in the form of a vector, a method of producing an anti-viral polypeptide or conjugate thereof, the anti-viral polypeptide itself, a conjugate or fusion protein comprising the anti-viral polypeptide, and compositions comprising an effective amount of the anti-viral polypeptide or conjugate or fusion protein thereof. Further provided are methods of inhibiting prophylactically or therapeutically a viral infection of a host.