National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2013

18. Reduction in the infectivity of the bovine spongiform encephalopathy agent by wet-heating at 155 ℃ for 20 min


The bovine spongiform encephalopathy (BSE) agent is resistant to conventional microbial inactivation procedures and thus threatens the safety of cattle products and by-products. To evaluate BSE inactivation, we performed quantitative analysis of wet-heat inactivation of BSE-infected cattle spinal cords. Using a highly sensitive bioassay, we found that infectivity in BSE cattle macerates fell as temperatures increased from 133 °C to 150 °C with no detection in samples treated above 155 °C. In dry cattle tissues, infectivity was detected even at 170 °C. Thus, BSE infectivity reduces with the increase in wet-heat temperatures but is overall less effective on tissues that are dehydrated prior to the wet-heat treatment. The results of the quantitative protein misfolding cyclic amplification assay also demonstrated that the level of the protease-resistant prion protein fell below the bioassay detection limit by wet-heat at 155 °C and higher. Our results show that BSE infectivity is strongly resistant to wet-heat inactivation and that it is necessary to pay attention to BSE decontamination in recycled cattle by-products.
(Influenza and Prion Disease Research Center)


Matsuura Y. et al (2013) Biochem. Biophys. Res. Commun. 432(1):86-91