Patent ID: 8592554

Claim:
An immunotoxin comprising (a) a ligand which is a variant of a CX 3 C chemokine that binds a constitutively internalizing CMV encoded chemokine receptor US28 expressed on a CMV infected cell and (b) a toxin that is cytotoxic to the CMV infected cell, wherein the ligand has increased specificity towards US28 as compared to the parental ligand and the ligand is a variant having at least 80% amino acid sequence identity to amino acids present at positions 25-100 of SEQ ID NO: 2 in the chemokine domain of human CX 3 CL1; and (i) the ligand is a variant mutated in position 31 of SEQ ID NO: 2, a variant mutated in position 38 of SEQ ID NO: 2, a variant mutated in position 60 of SEQ ID NO: 2, a variant mutated in position 68 of SEQ ID NO: 2, a variant mutated in position 71 of SEQ ID NO: 2, or a variant mutated in position 73 of SEQ ID NO: 2; or (ii) the ligand is a variant at one or more of amino acid residues in positions 33, 34 and 35 of SEQ ID NO: 2, wherein the one or more residues have been mutated or deleted.