Figure 4.

VZV TK is dispensable while VZV TS is required for optimal growth in cells and is critical for human skin organ culture. Cell-free VZV was added to ARPE-19 monolayers at 37 °C (A–C; 1:50 ratio) or introduced to adult human skin (D; 1 × 10⁴–10⁵ pfu/mL; 30 µL inoculum) by scarification, placed on NetWells, and incubated at 35 °C. Virus spread was monitored daily by bioluminescence imaging. Cell cultures were infected with up to 500 pfu/well. Skin was infected with 300–3000 pfu/piece of skin, depending on the viral titer that could be attained in ARPE-19 cells. VZV-ORF57-Luc was grown independently in ARPE-19 for each assay in (A–C), and directly compared to (A) VZV-ORF57-∆TK, (B) VZV-ORF57-∆TS, or (C) VZV-ORF57-∆TK∆TS under the same conditions. (D) Growth kinetics of ∆TK, ∆TS, and ∆TK∆TS in adult human skin explants were evaluated for significance compared to parental VZV-ORF57-Luc on DPI 7. VZV yield was calculated as the average Total Flux each day divided by the Total Flux on (A–C) DPI 1 or (D) DPI 2. Each point and line represent the mean ± SEM. (A–C) Student’s t-test or (D) one-way ANOVA with Dunnett’s post hoc test; * p < 0.05; ** p < 0.01, ns = not significant. n = 6 biological replicates.