BSE: Science & research - Animal by-products: Inactivation studies of TSE infectivity
Animal by-products are animal carcases, parts of carcases or products of animal origin that are not intended for human consumption. Legislation is in place regarding controls on the treatment and handling of animal by-products and controlling their use in animal feed in order to protect human and animal health.
TSE agents are particularly resistant to standard physical and chemical methods of inactivation and decontamination such as high temperature, low or high pH. Therefore, rendering practices may not completely inactivate TSE agents (hence the need for additional animal feed controls). Defra has funded research to investigate the effect of industrial processes on the nature and infectivity of TSE agents.
Recent research
- Research has been carried out to investigate the effect of the Carver-Greenfield rendering process on the nature of the BSE agent. The results found no evidence that the process affects the characteristics of the BSE strain (project SE0234);
- Ongoing research is investigating the ability of the “biolytic” process to inactivate TSE infectivity. This is a novel system of biorefinement, involving high pressure steam which processes the tissue at 190oC. It produces mineral and protein products which are useful as fertilizers or animal feed products. The survival of TSE infectivity in the system is being investigated (project SE1425);
- Studies have investigated the effect of temperature on infectivity using mouse bioassays (project SE1438).
Earlier studies on TSE infectivity inactivation
Earlier studies were funded by Defra and previously MAFF to investigate the inactivation of TSEs. This research was conducted in collaboration with other research funders, such as the Department of Health.
For example, previous research investigated:
- The effectiveness of various rendering practices at inactivating TSE agents using laboratory-scale copies (project SE0229);
- Pressurised steam with the addition of an alkaline compound as a means of inactivating TSE agents (project SE1434);
- The feasibility of using microwave techniques to dispose of infectious carcasses (project SE0218);
- The inactivation of TSEs by enzymes that survive high temperatures (thermophilic enzymes) (project SE0224).
Detection of mammalian material in animal feedstuffs
It is important that laboratory tests are developed which have suitable specificity and sensitivity to identify animal proteins in animal feed. Tests need to detect the proteins at levels sufficient to enforce EU and national regulations on the exclusion of mammalian protein.
Defra is currently supporting UK-research of a large collaborative European project to develop suitable validated methods for the species-specific detection and quantification of animal protein in animal feed (projects SE1797 & SE1798).
Page last modified: 7 March, 2008