Comparison of promoter activity of WSSV ie1 and CMV promoter in luciferase assays in different cell lines. The relative luciferase activity was expressed as fold activity 24 h post-transfection, and the data were from three transfections. The transfections were performed with the reporter plasmid phRL with WSSV ie1, CMV and SV40 promoter individually. CEF: transfections in chicken embryo fibroblasts; SF9: transfections in SF9 cells. Vero: transfections in Vero cells. p. value is less than 0.005, when WSSV ie promoter was compared with CMV promoter in SF9 cells, evaluated in t-test.