Immunochemical detection of prion protein on dipsticks prepared with crystalline bacterial cell-surface layers.

Background: Transmissible spongiform encephalopathy (TSE) represents a spectrum of diseases affecting humans and animals. A definitive diagnosis of TSEs is only possible by postmortem identification of pathologic prion protein in brain tissue that has been treated with protease. The pathologic protein is detected by Western blot analysis or ELISA methods. The bovine spongiform encephalopathy crisis and occurrence of a new variant of CJD has increased demand for rapid and simple assays.

Study Design And Methods: A dipstick assay has been developed for prion diagnosis based on a sandwich ELISA specific for prion protein, and crystalline bacterial cell-surface layers (S-layers) were used as an immobilization matrix. The usefulness of the dipstick assay was evaluated by determining the detection limit, comparison with other methods, and analysis of CJD samples.

Results: The sensitivity of the prion dipsticks was similar to that published for time-resolved fluorescence ELISA methods. After protease treatment, pathologic prion protein could be detected specifically.

Conclusion: The dipstick assay is a sensitive and specific test useful for the detection of prion protein. The simplicity of the S-layer dipstick lends itself to a variety of potential applications including field diagnostics.