Fig 1. Salubrinal-induced fusion of HSV-infected cells is dependent on accessory proteins.

(A) Diagram of relevant HSV-1 proteins involved in cell-to-cell spread and syncytia formation. The core fusion proteins are blue (gB, gH/gL, and gD), and proteins that can be altered to create syncytial variants are purple (gK, UL20, UL24, and gB). Two of the accessory glycoproteins are green (gE and gI), and three of the accessory tegument proteins are yellow (UL11, UL16, and UL21). (B) Vero cells were infected (MOI = 1) with HSV-1 strains KOS or 17 and incubated in medium containing DMSO or 50 μM salubrinal. At 12 hpi, the cells were immunostained for ZO-1 (red), and nuclei were stained with DAPI. Examples of syncytia are indicated (arrows). (C) Cells were infected with the KOS strain (MOI = 0.5) and incubated in the presence of salubrinal, as indicated. At 18 hpi, the cells were immunostained for ZO-1, and DAPI-stained nuclei were scored as being inside syncytia or within single cells. 1000 nuclei were scored per image for 3 replicates. Data are represented as mean ±SD, and statistical significance was determined by a student T-test. (D) Cells were infected (MOI = 0.5) with WT, gEΔCT, or ΔUL16 viruses and incubated in the presence of 50 μM salubrinal for 18 hours. DAPI-stained nuclei were scored as in (1C).