Figure 4. Lack of MV-GFP-H_AA-IL-13 cytopathic effect in normal (nontumor) cells.

(a) Western immunoblotting of lysates derived from normal human astrocytes and fibroblasts shows lack of expression of the interleukin-13 (IL-13) receptor α2 (IL-13Rα2). U87 cells expressing high levels of IL-13Rα2 and U118 cells (low expressors) were used as controls. (b) In contrast to infection with MV-GFP, treatment of normal human astrocytes and fibroblasts with MV-GFP-H_AA-IL-13 virus did not cause infection or fusion [multiplicity of infection (MOI) 1.0, 72 hours after infection). (c) Cell viability of normal human astrocytes and fibroblasts in response to infection with MV-GFP-H_AA-IL-13 and MV-GFP was determined by trypan blue exclusion assays and presented as percentage of uninfected cells. In contrast to MV-GFP, the IL-13 displaying retargeted strain had no significant cytopathic effect (MOI 1.0). (d) Western immunoblotting for the measles virus nucleocapsid N protein was performed in cell lysates derived from primary glioblastoma multiforme lines, normal human astrocytes, and fibroblasts 48 hours after viral infection with either MV-GFP or MV-GFP-H_AA-IL-13 (MOI 1.0). In contrast to MV-GFP infection, there was no expression of measles virus N protein after treatment of normal human astrocytes and fibroblasts with the IL-13 displaying retargeted strain, thus indicating lack of infection. In contrast, in the IL-13Rα2-positive line U87 there is abundant N protein expression after infection with the retargeted strain. GFP, green fluorescent protein.