Diagnostic efficacy of XQ-Station POCT, real-time PCR, and Droplet Digital PCR in detecting African swine fever virus.

Abstract

This study aimed to compare the diagnostic performance of the XQ-Station point-of-care real-time PCR (POCT) system and p72 droplet digital PCR (ddPCR) for African swine fever virus (ASFV) detection, using the WOAH-recommended p72 real-time PCR (qPCR) assay as the reference. A total of 132 clinical samples from 45 pigs, including oropharyngeal-nasal swabs, whole blood, and spleen tissues, were tested in parallel. Among 96 samples from ASFV-positive farms, qPCR, POCT, and ddPCR detected 83 (86.5%), 81 (84.4%), and 93 (96.9%) positive samples, respectively, while all 36 samples from an ASFV-negative farm tested negative. Compared with qPCR, POCT showed high agreement (κ = 0.968), relative sensitivity of 97.6%, specificity of 100%, and accuracy of 98.5%, with no significant difference in qualitative classification (p > 0.05). In contrast, ddPCR identified 10 additional positive samples, with substantial agreement (κ = 0.831; p < 0.01). Both assays effectively discriminated qPCR-positive and -negative samples (AUC = 0.988 and 0.984, respectively). Low viral DNA loads contributed to inter-platform discrepancies. Despite significant correlations, Bland-Altman analysis indicated insufficient quantitative agreement for interchangeable viral load quantification. POCT offers rapid field detection, whereas ddPCR provides complementary sensitivity for low viral DNA loads.