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Detection limitations of prion seeding activities in blood samples from patients with sporadic prion disease
Toshiaki Nonaka1, Yasushi Iwasaki2, Hiroyuki Horiuchi3
1Division of Cellular and Molecular Biology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki City, 852-8501, Japan.
Background:
Human prion diseases (HPDs) are fatal neurodegenerative disorders characterized by abnormal prion proteins (PrPSc). However, the detection of prion seeding activity in patients with high sensitivity remains challenging. Even though real-time quaking-induced conversion (RT-QuIC) assay is suitable for detecting prion seeding activity in a variety of specimens, it shows lower accuracy when whole blood, blood plasma, and blood-contaminated tissue samples are used. In this study, we developed a novel technology for the in vitro amplification of abnormal prion proteins in HPD to the end of enabling their detection with high sensitivity known as the enhanced quaking-induced conversion (eQuIC) assay.
Methods:
Three antibodies were used to develop the novel eQUIC method. Thereafter, SD50 seed activity was analyzed using brain tissue samples from patients with prion disease using the conventional RT-QUIC assay and the novel eQUIC assay. In addition, blood samples from six patients with solitary prion disease were analyzed using the novel eQuIC assay.
Results:
The eQuIC assay, involving the use of three types of human monoclonal antibodies, showed approximately 1000-fold higher sensitivity than the original RT-QuIC assay. However, when this assay was used to analyze blood samples from six patients with sporadic human prion disease, no prion activity was detected.
Conclusion:
The detection of prion seeding activity in blood samples from patients with sporadic prion disease remains challenging. Thus, the development of alternative methods other than RT-QuIC and eQuIC will be necessary for future research.
Insights
A new enhanced quaking-induced conversion (eQuIC) assay shows 1000-fold higher sensitivity for detecting abnormal prion proteins in brain tissue. However, prion seeding activity was not detected in blood samples from patients with sporadic human prion disease.
Area of Science:
- Neurodegenerative diseases
- Biochemistry
- Medical diagnostics
Background:
- Human prion diseases (HPDs) are fatal neurodegenerative disorders caused by abnormal prion proteins (PrPSc).
- Detecting prion seeding activity in patients, especially in blood samples, remains a significant diagnostic challenge.
- The real-time quaking-induced conversion (RT-QuIC) assay has limitations in accuracy with blood-related samples.
Purpose of the Study:
- To develop a novel, highly sensitive in vitro assay for amplifying abnormal prion proteins in HPDs.
- To enhance the detection capabilities for prion seeding activity in clinical specimens.
Main Methods:
- Development of the enhanced quaking-induced conversion (eQuIC) assay utilizing three human monoclonal antibodies.
- Analysis of prion seeding activity in brain tissue samples from prion disease patients using both conventional RT-QuIC and the novel eQuIC assay.
- Testing the eQuIC assay on blood samples from patients with sporadic human prion disease.
Main Results:
- The eQuIC assay demonstrated approximately 1000-fold greater sensitivity compared to the original RT-QuIC assay in detecting prion seeding activity.
- Despite enhanced sensitivity, the eQuIC assay did not detect prion activity in blood samples from the six patients with sporadic human prion disease.
Conclusions:
- Detecting prion seeding activity in blood from sporadic human prion disease patients remains difficult.
- Further research and development of alternative diagnostic methods beyond RT-QuIC and eQuIC are required for effective blood-based prion disease detection.
