FIG 3.

Survival and oncoselectivity following infection with VSV-LASV-GPC are interferon dependent. (A and B) IFN-α protects nontumor cells from VSV-LASV-GPC infection. Cultures of human U87 glioma (A) and normal cells, including human glia, human fibroblasts, and human neurons (B), were treated with 100 IU/ml IFN-α for 8 h before being infected with VSV-LASV-GPC at an MOI of 0.1. In spite of IFN treatment, strong viral infection was seen on glioma cells at 24 hpi; in contrast, little VSV-LASV-GPC infection was found on nontumor normal human cells. Scale bar, 100 μm. (C) Cultures containing human neurons and glia were infected with VSV-wtG or VSV-LASV-GPC at an MOI of 1 in the presence or absence of 100 IU/ml IFN-α, respectively. IFN had little effect in reducing infection of neurons by VSV-wtG but substantially attenuated infection of neurons by VSV-LASV-GPC (P < 0.05). (D) Intracranial injection of VSV-wtG (n = 3) and VSV-LASV-GPC (n = 5) into IFN-α/β-R^−/− mice resulted in death within 3 days (VSV-wtG) and 7 days (VSV-LASV-GPC). VSV-LASV-GPC injection in normal mice (IFN-α/β-R^+/+) did not result in neurotoxicity or mortality in any mice. (E to G) Typical microscopic images of injected striatum sections showing VSV-LASV-GPC infection in IFN-α/β-R^−/− and IFN-α/β-R^+/+ mice. Scale bar, 100 μm. (H) Binding of VSV-wtG and VSV-LASV-GPC was assessed by qRT-PCR following incubation at 4°C, and binding and internalization at 37°C on neurons or U87 glioma cells (n = 3; SEM). (I) Quantification of viral replication in neurons and U87 glioma cells was assessed by plaque assay at 15 and 24 hpi. VSV-wtG produced equal titers of progeny in both neurons and glioma. (J) In contrast, VSV-LASV-GPC progeny production was strongly reduced in neurons compared to human glioma.