PrPSc detection in formalin-fixed paraffin-embedded tissue by ELISA.

BACKGROUND

Formalin-fixed paraffin-embedded tissue is regularly employed in the diagnosis of transmissible spongiform encephalopathies (TSE) by immunohistochemistry (IHC), the standard by which all other TSE diagnostic protocols are judged. While IHC affords advantages over diagnostic approaches that typically utilize fresh or frozen tissue, such as Western blot and ELISA, the process of fixing, staining, and analyzing individual sections by hand does not allow for rapid or high throughput screening. However, preservation of tissues in formalin is not dependent upon the availability of refrigeration.

FINDINGS

Formalin-fixed paraffin-embedded tissues from TSE transmission studies of scrapie in sheep, chronic wasting disease in white-tailed deer or transmissible mink encephalopathy in cattle were cut at 5 μm thickness. Samples containing the tissue equivalent of as little as one 5 μm section can be used to readily discriminate positive from negative samples.

CONCLUSIONS

This approach cannot replace IHC but may be used along with IHC as both a more rapid and readily high throughput screen where fresh or frozen tissues are not available or impractical.