Report of the first oral inoculation of BSE prion into cattle in Japan

Abstract

A Prion Disease Research Center at the National Institute of Animal Health (NIAH) was established to conduct comprehensive research on BSE in response to the discovery of bovine spongiform encephalopathy (BSE) in Japan. A new research facility for the center has been constructed. It was designed as a biosafety level (BSL) 3 facility with the capacity to inoculate and hold experimental animals. Experiments have begun to infect cattle with BSE orally. This route of inoculation simulates the feeding of contaminated meat and bone meal that caused pandemic occurrence of BSE in the UK. An abnormal isoform of the prion protein (PrP^Sc) accumulates in BSE affected cattle. The purpose of this study is to examine the spread of the abnormal prion from digestive tract to the central nervous system and to describe the pathological changes in cattle during the course of infection. Atypical BSE and young BSE cases have been found in the abattoir surveillance program. As a result the cattle used in this experiment were imported from Australia, a country free of BSE, to exclude the possibility of prior BSE infection before inoculation. Each calf (Holstein heifer, 10-months old) was inoculated orally with 5g of brain stem from BSE infected cattle (courtesy provided by Veterinary Laboratory Agency, Weybridge, UK) into the rumen with a catheter. The cattle will be euthanized at intervals during the clinical stages of disease. Infectivity from different tissues at different stages of clinical disease as well as the deposition of PrP^Sc will be analyzed. Other factors that may be related to the pathogenesis of the BSE prion will be investigated.