Ring trial of 2nd generation RT‐QuIC diagnostic tests for sporadic CJD

Abstract

Objective: Real-time quaking-induced conversion (RT-QuIC) assays detect prion-seeding activity in a variety of human biospecimens, including cerebrospinal fluid and olfactory mucosa swabs. The assay has shown high diagnostic accuracy in patients with prion disorders. Recently, advances in these tests have led to markedly improved diagnostic sensitivity and reduced assay times. Accordingly, an algorithm has been proposed that entails the use of RT-QuIC analysis of both sample types to diagnose sporadic Creutzfeldt-Jakob disease with nearly 100% accuracy. Here we present a multi-center evaluation (ring trial) of the reproducibility of these improved "second generation" RT-QuIC assays as applied to these diagnostic specimens. Methods: Cerebrospinal fluid samples were analyzed from subjects with sporadic Creutzfeldt-Jakob (n = 55) or other neurological diseases (n = 45) at multiple clinical centers. Olfactory mucosa brushings collected by multiple otolaryngologists were obtained from nine sporadic Creutzfeldt-Jakob disease cases and 19 controls. These sample sets were initially tested blindly by RT-QuIC by a coordinating laboratory, recoded, and then sent to five additional testing laboratories for blinded ring trial testing. Results: Unblinding of the results by a third party indicated 98-100% concordance between the results obtained by the testing of these cerebrospinal fluid and nasal brushings at the six laboratories. Interpretation: This second-generation RT-QuIC assay is highly transferrable, reproducible, and therefore robust for the diagnosis of sporadic Creutzfeldt-Jakob disease in clinical practice.

Concordance of cerebrospinal fluid real‐time quaking‐induced conversion across the European Creutzfeldt–Jakob Disease Surveillance Network

“…The high degree of concordance between all 13 laboratories that participated in this study is encouraging and helps to ensure that sCJD surveillance data between countries can be compared in a meaningful manner. These results also support the findings of previous ring-trials that found CSF RT-QuIC to be a robust and reliable test with a high degree of concordance between laboratories [15,17,19].…”

The Use of Real-Time Quaking-Induced Conversion for the Diagnosis of Human Prion Diseases

“…There was a strong agreement between three studies reporting a high sensitivity of the IQ-CSF for the VV2 subtype (96.4–100%), which was only slightly lower for MV2K individuals (88.9–92.5%) ( Table 5 ) ( Foutz et al, 2017 ; Franceschini et al, 2017 ; Rhoads et al, 2020 ). A recent ring trial confirmed the result on VV2 cases ( Orrú et al, 2020 ). In contrast, the only study testing these histotypes with PQ-CSF in a significant number of patients reported a suboptimal performance in both groups (sensitivity 77.8% in VV2 and 80.8% in MV2K) ( Lattanzio et al, 2017 ).…”

“…Using CSF, the PQ protocol yielded a slightly lower sensitivity (88.8–94.1%) ( Bongianni et al, 2017 ; Lattanzio et al, 2017 ; Hamaguchi et al, 2020 ) compared to IQ-CSF (93.0–100%) ( Bongianni et al, 2017 ; Foutz et al, 2017 ; Franceschini et al, 2017 ; Rhoads et al, 2020 ). Moreover, two independent ring trials assessing the agreement among laboratories demonstrated a complete concordance of RT-QuIC results and 100% sensitivity for both these recombinant substrates ( McGuire et al, 2016 ; Orrú et al, 2020 ).…”

“…To date, CSF is by far the most studied matrix. CSF RT-QuIC using different recombinant substrates showed reproducible results among research groups and high inter-laboratory agreement in ring trials ( McGuire et al, 2016 ; Orrú et al, 2020 ). Conversely, despite the promising initial results, RT-QuIC using alternative matrices, such as OM and skin, is still limited to a few specialized laboratories, confirmatory studies are lacking, and the performance of different recombinant substrates are largely unknown.…”

Evidence of SARS-CoV-2 in nasal brushings and olfactory mucosa biopsies of COVID-19 patients

“…Considering that NB is a non-invasive, inexpensive, rapid, and painless procedure [ 24 ] and that our results reveal accuracy of this procedure for detecting SARS-CoV-2 invasion of the OM, it appears that NB can be used for diagnostic purposes related to the possible early detection of viral invasion of the olfactory neuroepithelium in COVID-19 patients.…”