Computationally-driven epitope identification of PEDV N-protein and its application in development of immunoassay for PEDV detection.

The nucleocapsid (N) protein is a suitable candidate for early diagnosis of porcine epidemic diarrhea virus (PEDV). Here, we identified the linear B-cell epitopes of the PEDV N-protein by integrating a computational-experimental framework and constructed three-dimensional (3D) structure model of the N protein using the ColabFold program in Google Colaboratory. Furthermore, we prepared the monoclonal antibodies against the predicted epitopes and recombinant N protein, respectively, and selected pairing mAbs (named 9C4 and 3C5) to develop a double-antibody sandwich immunochromatographic test strip using CdSe/ZnS quantum dots (QDs)-labelled 9C4 and 3C5 as capture and detection antibodies, respectively. This strip can specifically detect PEDV within 10 min with a detection limit of less than 6.25 × 103 TCID50/mL. In comparison with RT-PCR for testing 90 clinical samples, the relative sensitivity and specificity of the strip were found to be 98.0% and 100%, respectively, with a concordance rate of 98.9% and a kappa value of 0.978, indicating that QDs-ICTS is a reliable method for the application of PEDV detection in clinical samples.

Point-of-Care Tests for Rapid Detection of Porcine Epidemic Diarrhea Virus: A Systematic Review and Meta-Analysis.

The timely and accurate diagnosis of porcine epidemic diarrhea virus (PEDV) infection is crucial to reduce the risk of viral transmission. Therefore, the objective of this review was to evaluate the overall diagnostic accuracy of rapid point-of-care tests (POCTs) for PEDV. Studies published before 7 January 2022 were identified by searching PubMed, EMBASE, Springer Link, and Web of Science databases, using subject headings or keywords related to point of care and rapid test diagnostic for PEDV and PED. Two investigators independently extracted data, rated risk of bias, and assessed the quality using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The bivariate model and the hierarchical summary receiver operating characteristic (HSROC) model were used for performing the meta-analysis. Threshold effect, subgroup analysis, and meta-regression were applied to explore heterogeneity. Of the 2908 records identified, 24 eligible studies involving 3264 specimens were enrolled in the meta-analysis, including 11 studies on evaluation of lateral flow immunochromatography assay (ICA)-based, and 13 on nucleic acid isothermal amplification (NAIA)-based POCTs. The overall pooled sensitivity, specificity and diagnostic odds ratio (DOR) were 0.95 (95% CI: 0.92-0.97), 0.96 (95% CI 0.88-0.99) and 480 (95% CI 111-2074), respectively; for ICA-based POCTs and the corresponding values for NAIA-based, POCTs were 0.97 (95% CI 0.94-0.99), 0.98 (95% CI 0.91-0.99) and 1517 (95% CI 290-7943), respectively. The two tests showed highly comparable and satisfactory diagnostic performance in clinical utility. These results support current recommendations for the use of rapid POC tests when PEDV is suspected.