Technical Abstract: The potential use of ricin as an agent of biological warfare highlights the need to develop fast and effective methods to detect biologically active ricin. The current “gold standard” for ricin detection is an in vivo mouse bioassay; however, this method is not practical to test on a large number of samples, and raises ethical concerns with regard to the use of experimental animals. In this work we generated adenoviral vectors that express the green fluorescent protein (GFP) gene and used the relative fluorescence intensity in transduced cells for quantitative measurement of biologically active ricin in food without added substrates or use of cell fixation methods.