Viability of cells infected with herpes simplex virus (HSV) 1 and 2 at three stages during neuronal differentiation measured 48 h post-infection at MOI = 0.1. (A) HSV-1 infection does not affect the cell viability of iPSCs, while HSV-2 infection reduces cell viability of iPSCs by 14.6% compared with non-infected control iPSCs. Bars represent mean of six separate experiments on two iPSC lines +/− SEM. (B) HSV-1 and HSV-2 infections reduce cell viability of NPCs by 36.0% and 57.6%, respectively, compared with non-infected control NPCs. Bars represent mean of five separate differentiations from two iPSC lines +/− SEM. (C) Neuron viability is slightly reduced 48 h after infection (15.8% and 20.8% by HSV-1 and HSV-2, respectively). No significant difference in cytopathic effect is observed between HSV-1 and HSV-2 in neurons. Bars represent mean of four separate differentiations on two iPSC lines +/− SEM. Viability of human fibroblasts (D) infected with herpes simplex virus (HSV) 1 and 2 measured 48 h post-infection at MOI = 0.1. Bars represent mean of three separate experiments +/− SEM. ** p < 0.01, *** p < 0.001 and **** p < 0.0001 from Student’s t-test.