TNF and infection: However, when TNF-a was added to the medium for 24 h, it induced an obvious cytotoxicity in infected SH-SY5Y cells, which could have negatively impacted their susceptibility to infection (one-way ANOVA, 4.80 ± 0.77 vs. 23.0 ± 2.6%, p < 0.001 for comparison between MOI 5.0 condition and MOI 5.0 + TNF-a) (Figure S1C).