BSE transmission studies with particular reference to blood

Area of Science:

• Veterinary Neurology
• Prion Disease Research
• Pathogenesis Studies

Background:

• Bovine spongiform encephalopathy (BSE) is a fatal neurodegenerative disease in cattle.
• Understanding tissue infectivity is crucial for disease control and public health.
• Previous studies indicated infectivity primarily within the central nervous system (CNS).

Purpose of the Study:

• To comprehensively investigate the distribution of BSE infectivity in cattle.
• To determine infectivity levels in various tissues, including blood, during natural and experimental BSE.
• To compare BSE detection sensitivity between cattle and mice.

Main Methods:

• Analysis of tissues from cattle with natural BSE.
• Oral challenge of cattle with BSE-infected brain material in a pathogenesis study.
• Experimental parenteral challenge of cattle and mice with brain, spleen, and lymph node pools.
• Dilution experiments to assess infectivity thresholds.

Main Results:

• In natural BSE, infectivity was restricted to the CNS (brain, spinal cord, retina).
• No infectivity was detected in approximately 50 other tissues, including blood components.
• Experimental oral challenge showed no infectivity in blood or its components.
• Parenteral challenge experiments indicated brain transmits disease, while spleen and lymph nodes did not (studies incomplete).
• Cattle are approximately 1000 times less sensitive to BSE infectivity than mice.

Conclusions:

• BSE infectivity in cattle is primarily localized within the CNS and retina.
• Blood and most other tissues are not infectious for BSE.
• Mice are more sensitive indicators of BSE infectivity than cattle.