Fig. (1) Strategies to improve oHSV therapy of malignant glioma. Each of the different strategies discussed in detail in the text are shown schematically. IRS= C134 chimeric HSV expressing IRS gene from HCMV; WT= retargeted viruses that have wildtype ICP34.5 but can only infect cells with upregulated tumor-specific receptors; *γ₁34.5= ICP34.5 expressed from tumor-specific promoters; Δ= γ₁34.5 deleted viruses.