In pre-clinical studies oHSV engineered to express the murine genes encoding interleukin-12 (IL-12), interleukin-4 (IL-4), chemokine (C-C) motif ligand 2 (CCL2), or human granulocyte-macrophage colony stimulating factor (GM-CSF) were reported to reduce tumor burden or improve survival of tumor bearing mice as compared to parental non-cytokine encoding oHSV [16-20]. The gene discussed is IL4; the disease is neoplasm.