The structural glycoprotein E rns (an envelope protein with RNase activity) of classical swine fever virus (CSFV) is not well characterized with respect to its antigenic structure and organization.Here, we investigated the antigenic sites on E rns by raising mAbs against the Escherichia coli expressed E rns of CSFV strain Alfort/187 and defined the B-cell epitopes recognized by these antibodies. Eighteen mAbs to E rns were identified and they were classified as either immunoglobulin subclass G1 or G2b. Using an array of overlapping 12-mer peptides, spanning aa 27-227 of E rns , the epitopes for 12 mAbs were mapped to a high resolution of six to eight residues, which cluster in five discrete locations, 31 GIWPEKIC 38 (group I), 65

Contamination of rendered animal byproducts with central nervous system tissues (CNST) from animals with bovine spongiform encephalopathy is considered one of the vehicles of disease transmission. Removal from the animal feed chain of CNST originated from cattle of a specified age category, species-labeling of rendered meat products, and testing of rendered products for bovine CNST are tasks associated with the epidemiological control of bovine spongiform encephalopathy. A single-step TaqMan real-time reverse transcriptase (RRT) PCR assay was developed and evaluated for specific detection of bovine glial fibrillary acidic protein (GFAP) mRNA, a biomarker of bovine CNST, in rendered animal by-products. An internal amplification control, mammalian b -actin mRNA, was coamplified in the duplex RRT-PCR assay to monitor amplification efficiency, normalize amplification signals, and avoid false-negative results. The functionality of the GFAP mRNA RRT-PCR was assessed through analysis of laboratory-generated binary mixtures of bovine central nervous system (CNS) and muscle tissues treated under various thermal settings imitating industrial conditions. The assay was able to detect as low as 0.05 % (wt/wt) bovine brain tissue in binary mixtures heat treated at 110 to 130°C for 20 to 60 min. Further evaluation of the GFAP mRNA RRT-PCR assay involved samples of industrial rendered products of various species origin and composition obtained from commercial sources and rendering plants. Low amounts of bovine GFAP mRNA were detected in several bovine-rendered products, which was in agreement with declared species composition. An accurate estimation of CNS tissue content in industrial-rendered products was complicated due to a wide range of temperature and time settings in rendering protocols. Nevertheless, the GFAP mRNA RRT-PCR assay may be considered for bovine CNS tissue detection in rendered products in combination with other available tools (for example, animal age verification) in inspection programs.