2007 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project with Dr. Maria Caramelli from the Italian BSE Reference Laboratory in Turin, Italy, is to conduct comparative studies with the U.S. bovine spongiform encephalopathy (BSE) isolate and the atypical BSE isolates identified in Italy. The studies will cover the following areas: 1. Evaluation of present diagnostics tools used in the U.S. for the detection of atypical BSE cases. 2. Molecular comparison of the U.S. BSE isolate and other typical BSE isolates with atypical BSE cases. 3. Studies on transmissibility and tissue distribution of atypical BSE isolates in cattle and other species. 1b.Approach (from AD-416) This project will be done as a Specific Cooperative Agreement with the Italian BSE Reference Laboratory, Istituto Zooprofilattico Sperimentale del Piemonte, in Turin, Italy. It is essential for the U.S. BSE surveillance program to analyze the effectiveness of the U.S diagnostic tools for detection of atypical cases of BSE. Molecular comparisons of the U.S. BSE isolate with atypical BSE isolates will provide further characterization of the U.S. BSE isolate. Transmission studies are already underway using brain homogenates from atypical BSE cases into mice, cattle and sheep. It will be critical to see whether the atypical BSE isolates behave similarly to typical BSE isolates in terms of transmissibility and disease pathogenesis. If transmission occurs, tissue distribution comparisons will be made between cattle infected with the atypical BSE isolate and the U.S. BSE isolate. Differences in tissue distribution could require new regulations regarding specific risk material (SRM) removal. 3.Progress Report This report serves to document research conducted under a specific cooperative agreement between ARS and the Italian Reference Centre for Animal TSE (CEA) at the Istituto Zooprofilattico Sperimentale, Turin, Italy. Additional details of research can be found in the report for the parent project 3625-32000-086-00D, Transmission, Differentiation, and Pathobiology of Transmissible Spongiform Encephalopathies. The aim of the cooperative research project conducted by the CEA and ARS is to compare the U.S. bovine spongiform encephalopathy (BSE) isolates and the bovine amyloidotic spongiform encephalopathy isolates (BASE) identified in Italy. The first objective was to determine whether diagnostic methods routinely used by USDA are able to identify the Italian BASE cases. For this purpose, CEA received the immunohistochemistry (IHC) protocol developed by APHIS-USDA. The IHC protocol was reproduced and standardized in the CEA laboratory and will be applied to the Italian BSE and BASE cases. Furthermore, fixed brainstem sections and frozen brainstem material from Italian BSE and BASE cases were sent to ARS for analysis using USDA IHC and Western blot (WB) methods. At present, western blot analyses have been completed, as reported in the scientific reports 2005 and 2006. Since the Ventana NexES IHC Staining System is no longer in production and therefore could not be purchased in Italy, a researcher from our group will be sent to the NVSL laboratories in Ames in order to compare the USDA and Italian IHC methods. During the past year there were regular contacts with the cooperator. These contacts included one site visit and e-mail correspondence to discuss the progress of the project.