Infection of RK13 cells with EHV-1ΔgH. RK13 cells were transfected with either EHV-1ΔgH DNA (a) or EHV-1 parental DNA (b). EHV-1ΔgH was also transfected into RK13/gH1 cells (c). Recovered virus was collected from RK13/gH1 cells and used to infect naïve RK13 cells (d). Infected cells appear green as all viruses express EGFP. Cells were inspected with a fluorescent microscope (Zeiss Axiovert) and images were taken with a CCD camera (Zeiss Axiocam). The bar represents 100 μm.