Schematic representation of the sequence arrangements of the wild-type parent virus HSV-1(F) and R5111 and the chimeric gD contained in recombinant viruses R5121, R5113, R5123, R5141, and R5144. In all recombinant viruses, residues 68–78 of gB were deleted and IL-13 was inserted in place of residues 1–140 of gC. In R5111, R5121, and R5113, the signal sequence and residues 1–24 of gD were retained. In R5123, the residues 1–33 were deleted and only the signal peptide sequence of gD was retained. In R5141 and R5144, the signal peptide sequence of gD was replaced by that of IL-13. In addition, these two chimeric gDs contain additional amino acid substitutions as shown. The IL-13 inserted in R5121 and R5113 recombinant viruses carried the E13Y mutation, in which the glutamic acid was substituted by tyrosine. E13Y substitution restricts IL-13 binding to the IL-13Rα2 (52). R5121, R5141, and R5144 carried a wild-type IL-13 copy in gD.