Real‐time quaking‐induced conversion assay using a small‐scale substrate production workflow for the diagnosis of Creutzfeldt‐Jakob disease

• Published in: Journal of neurochemistry Vol. 166; no. 2; pp. 403 - 413
• Main Authors: Thanapornsangsuth, Poosanu, Chongsuksantikul, Adipa, Saraya, Abhinbhen W., Hiransuthikul, Akarin, Hemachudha, Thiravat
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01-07-2023
• Subjects: Aged; Cerebrospinal fluid; Conversion; Creutzfeldt-Jakob disease; Creutzfeldt-Jakob Syndrome - cerebrospinal fluid; Creutzfeldt-Jakob Syndrome - diagnosis; Creutzfeldt-Jakob Syndrome - pathology; diagnostic biomarker; Dialysis; EEG; Electronic health records; Electronic medical records; Female; Health risks; Humans; low‐ and middle‐income countries; Magnetic resonance imaging; Male; Middle Aged; Performance evaluation; prion disease surveillance; Prion Diseases; Prion protein; Prion Proteins; Prions; Public health; real‐time quaking‐induced conversion assay; Sensitivity; Sensitivity and Specificity; Substrates; Surveillance; Workflow; low- and middle-income countries; diagnostic biomarker; prion disease surveillance; real-time quaking-induced conversion assay; Creutzfeldt-Jakob disease
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/jnc.15841

The lack of a dedicated surveillance program for prion disease, particularly in low‐ and middle‐income countries (LMICs), has hindered the global effort to address this public health threat. Although cerebrospinal fluid (CSF) Real‐time quaking‐induced conversion (RT‐QuIC) is considered the most reliable test for sporadic Creutzfeldt‐Jakob disease (sCJD), its availability in LMICs is limited because of its cost and technical difficulty in generating the recombinant prion protein substrate (recPrP). This study aimed to evaluate the performance of RT‐QuIC with recPrP produced in‐house through a small‐scale method—that is, the application of reusable prepacked chromatography columns and subsequent dialysis. Here, CSF specimens from patients suspected of having prion disease were consecutively collected and stored between October 2015 and January 2023. Electronic medical record data were reviewed to clinically classify participants as probable sCJD or non‐sCJD. CSF RT‐QuIC was performed using in‐house recPrP. Its specificity and sensitivity for diagnosing probable sCJD were reported, along with details of other clinical data and investigations. We found that among 39 eligible participants, with a median (interquartile range) age of 64 (56–70) years and 16 (41%) female, 13 had probable sCJD and the remaining 26 unequivocally suffered from nonprion disorders. Magnetic resonance imaging and electroencephalogram were suggestive of sCJD in 100% (13/13) and 46.2% (6/13) of sCJD participants, respectively. RT‐QuIC was positive in 12/13 sCJD participants (sensitivity 0.92, 95% confidence interval [CI] 0.67–0.99) and negative in all non‐sCJD participants (specificity 1.00, 95% CI 0.87–1.00). CSF tau/p‐tau ratio showed sensitivity and specificity of 0.62–1.0 and 0.85–1.0, respectively. In summary, RT‐QuIC using recPrP generated through a small‐scale workflow demonstrated great performance in detecting sCJD. Given its performance results along with its low cost, this technique could feasibly be implemented in LMICs and potentially be the first step toward establishing local prion disease surveillance programs.
Real‐time quaking‐induced conversion (RT‐QuIC) assay, which is the most reliable diagnostic test for sporadic Creutzfeldt‐Jakob disease (sCJD), is not available in low‐ and middle‐income countries because of its cost and the technical difficulty of generating the recombinant prion protein substrate (recPrP). We described a simpler, more economical method of producing recPrP. By testing CSF specimens from patients in whom sCJD is suspected, we showed that RT‐QuIC analysis using our substrate is as accurate as reported in previous studies that used conventionally generated substrate.