FIG. 3.

The ICR in the MDV-1 bicistronic transcript has IRES activity by fluorescence microscopy. (A) List of bicistronic constructs used for transfection of DF-1 cells. The constructs are based on the pIRES2-AcGFP vector. The sequence to be tested for IRES activity (ICR) was cloned between the RFP and GFP genes. The EMCV IRES was used as a positive control. (B) Results of transfection with the pRG-ICR/MDV DNA construct (left) and the pRG-IRES/EMCV DNA construct (right). Live cells were examined under a fluorescence microscope with the appropriate filters to reveal fluorescent cells or under a bright field (BF) to visualize all cells.