Lozhkina O. Development of the laboratory diagnostic system of bovine spongiform encephalopathy in Ukraine

The dissertation is devoted to the development of the laboratory diagnostic system for bovine spongiform encephalopathy (BSE) as a part of epizootic surveillance and preventive measures of the disease in Ukraine. The system of BSE laboratory diagnostics in Ukraine was developed in compliance with OIE requirements and current systems of diagnostics in leaning EU countries. One of its important components is execution of mandatory laboratory investigations of brain tissue from animals of risk group and BSE suspects and monitoring investigations of brain tissue from healthy indigenous animals after slaughter. There were determined the criteria and developed the diagnostic system providing the evaluation of country's status on BSE. The results of 80,266 mandatory diagnostic and monitoring examinations on BSE carried out in Ukraine from 1999 to 2012 were analyzed; no positive results were found. A histological method of BSE diagnostics was modified using modern histological equipment (STP 120, HMS 70, AP 240) and main reasons of obtaining inconclusive results of histological examination of brain tissue (autolysis, freezing) were determined. A domestic version of immunohistochemistry ( IHC ) for BSE diagnostics, which combines some advantages of its existing variants in different countries and comprises the application of monoclonal antibodies to prion-protein SAF 84 (SPI bio, France), use of visualization system, developed on avidin-biotin and streptavidin-peroxidase methods, and recovery of pathologic prion antigen by combined enzyme-thermal protocol was developed. The developed IHC method of BSE diagnostics significantly decreases the likelihood of non-specific binding of antibodies, allows to work with autolized or frozen tissues, and reduces the duration of diagnostic tests compared to variations of IHC used in other countries. The following prion-tests were tried and implemented into practice of BSE laboratory diagnostics in Ukraine: Prionics®-Check Westrn as confirmatory and screening test and Prionics®-Check PrioSTRIP and IDEXX BSE HerdChek BSE as rapid tests. A set of regulations, state and industry standards, guidelines, recommendations and forms of state-required reports on laboratory diagnostics of BSE, which provides a full scientific support of diagnostic and preventive measures and stable epizootic welfare of Ukraine on BSE was developed and implemented into practice.