Currently, diagnostic tests for bovine spongiform encephalopathy (BSE) are only applicable to brain tissues collected after the death of the animal and so cannot be used for early preclinical diagnosis. To address this issue, a protein misfolding cyclic amplification (PMCA) technique was applied to detect small amounts of PrPSc in the saliva of preclinical BSE cattle that orally exposed BSE-affected brainstem. After three rounds of amplification with phosphotungstic acid precipitation by serial-PMCA, PrPSc was amplified from concentrated saliva samples. PrPSc in the saliva could be detected within 2 months of the clinical onset of the disease. Although large amounts of PrPSc were accumulated throughout the brain of necropsied animals at the terminal stage of the disease, no positive signal was detected in the salivary glands by immunohistochemistry or western blotting analysis. This study suggests that the PMCA technique using the saliva sample may help for the presumptive and antemortem diagnosis of BSE in cattle.
(Prion Disease Research Center)
Okada H. et al. (2012) Emerg. Infect. Dis. 18(12): 2091-2092