Figure 6.

LACV infection of HaCaT cells induces cell death in non-infected bystander cells. (A) HaCaT cells were infected at a MOI 0.5 PFU/cell. At the indicated hpi, cells were harvested and analyzed by flow cytometry for LACV Gc expression and for cell viability using Zombie Red™ dye. Data are expressed as number of Gc-positive and Gc-negative viable cells. (B–D) Media from LACV-infected or mock-infected HaCaT cells were collected at 24 hpi (B) and 48 hpi (B–D) and were UV-treated to inactivate virus. (B) Naïve cells were treated for 48 h with UV-inactivated media and cell viability was determined by PI staining. (C) Alternatively, cells were treated with UV-inactivated media, and caspase activity was determined by Caspase-Glo-3/7, -9 or -8 assays. Data are expressed as fold change over that seen with cultures treated with media from mock-infected cells (M48). (D) Naïve HaCaT cells were pre-treated with 40 μM of Z-VAD-FMK followed by treatment with the indicated media from mock-infected (M48) or LACV-infected cells (L48). After treatment for 48 h, cell viability was determined by PI staining. Values are the mean of three replicates with error bars indicating standard deviation and * indicating p-values of <0.05, ** indicating p-values of <0.01 and *** indicating p-values of < 0.001.