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Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie
D M Taylor1, H Fraser, I McConnell
1BBSRC & MRC Neuropathogenesis Unit, Institute for Animal Health, Edinburgh, U.K.
Abstract:
Macerates of bovine brain infected with bovine spongiform encephalopathy (BSE) agent, and rodent brain infected with the 263K or ME7 strains of scrapie agent, were subjected to porous-load autoclaving at temperatures between 134 and 138 degrees C for < or = 60 min. Bioassay in rodents showed that none of the regimens produced complete inactivation. Homogenates of BSE-infected bovine brain were exposed for < or = 120 min to solutions of sodium hypochlorite or sodium dichloroisocyanurate containing < or = 16,500 ppm available chlorine. There was no detectable survival of infectivity after the hypochlorite treatments but none of the dichloroisocyanurate solutions produced complete inactivation. Homogenates of BSE-infected bovine brain, and rodent brain infected with the 263K and ME7 strains of scrapie agent, were exposed for < or = 120 min to 1M or 2M sodium hydroxide but no procedure produced complete inactivation of all agents tested.
Insights
Autoclaving, sodium hypochlorite, and sodium hydroxide treatments failed to completely inactivate transmissible spongiform encephalopathy agents like bovine spongiform encephalopathy (BSE) and scrapie. Further decontamination strategies are crucial for prion safety.
Area of Science:
- Veterinary Medicine
- Neuroscience
- Infectious Diseases
Background:
- Transmissible spongiform encephalopathies (TSEs) pose significant public health and animal health challenges.
- Bovine spongiform encephalopathy (BSE) and scrapie are fatal neurodegenerative diseases caused by prions.
- Effective decontamination methods are essential to prevent the spread of these agents.
Purpose of the Study:
- To evaluate the efficacy of autoclaving, sodium hypochlorite, and sodium hydroxide in inactivating TSE agents.
- To assess the complete inactivation of infectious agents from infected brain tissues.
Main Methods:
- Porous-load autoclaving of infected brain macerates at 134-138°C for up to 60 minutes.
- Exposure of infected brain homogenates to sodium hypochlorite and sodium dichloroisocyanurate solutions (up to 16,500 ppm available chlorine) for up to 120 minutes.
- Treatment of infected brain homogenates with 1M or 2M sodium hydroxide for up to 120 minutes.
- Rodent bioassays were used to determine the survival of infectivity.
Main Results:
- Autoclaving regimens did not achieve complete inactivation of BSE or scrapie agents.
- Sodium hypochlorite treatments eliminated detectable infectivity of BSE agent.
- Sodium dichloroisocyanurate solutions failed to completely inactivate the BSE agent.
- Sodium hydroxide treatments at tested concentrations and durations did not completely inactivate all tested agents.
Conclusions:
- Standard autoclaving and tested chemical treatments are insufficient for complete inactivation of BSE and scrapie agents.
- Sodium hypochlorite shows promise but requires further optimization for complete prion decontamination.
- Development of robust sterilization protocols is critical for TSE agent control.