title: Sensitive bioassay for detection of biologically active ricin in food.
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 gene and used the relative fluorescence units intensity inhibition by transduced cells for  quantitative measurement of biologically active ricin. The detection limit of the assay was 200 pg/ml, which is over 500,000 times greater than the adult human lethal oral dose. The inhibition of fluorescence intensity between ricin treatment and control was higher in 72-h posttransduction  Vero cells than 24-h human embryonic kidney cells. Therefore, to detect biologically active ricin in food matrices that might influence the assay, we used 72-h posttransduction Vero cells. This simple assay could be used for large-scale screening to detect biologically active ricin in food  without added substrates or use of cell fixation methods.
authors.affiliation: U.S. Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA 94710, USA. reuven.rasooly@ars.usda.gov
authors.forename: Reuven
authors.initials: R
authors.lastname: Rasooly
authors.forename: Xiaohua
authors.initials: X
authors.lastname: He
mesh_terms: D000818:Animals; D001681:Biological Assay; D023482:Bioterrorism; D002522:Chlorocebus aethiops; D005506:Food Contamination / Q000032:analysis*; D049452:Green Fluorescent Proteins / Q000378:metabolism*; D006801:Humans; D008163:Luminescent Measurements; D012276:Ricin / Q000302:isolation & purification*; D014709:Vero Cells
chemical_list: D049452:Green Fluorescent Proteins; D012276:Ricin