African swine fever virus (ASFV) poses a major transboundary threat to global swine production, underscoring the need for rapid and field-deployable diagnostic tools. Although quantitative polymerase chain reaction (qPCR)-based assays are the standard molecular assay for ASFV detection, their reliance on centralized laboratory infrastructure, multi-step sample preparation, and trained personnel limit their utility for timely decision-making at the point of need (PON). Here, we report a portable molecular diagnostic platform that enables colorimetric quantitative loop-mediated isothermal amplification (qLAMP) directly from diluted whole blood on microfluidic paper-based analytical devices (PADs). The assay targets the conserved ASFV viral protein 72 (VP72) and topoisomerase II (TOPII) genes and incorporates objective image-based colorimetric signal analysis to reduce user-dependent interpretation. Using plasmid DNA spiked into whole blood diluted to 5% (v/v) in 5% D-mannitol, the PAD-LAMP assay achieved a limit of detection (LOD) of 25 copies per reaction (67 copies/L of whole blood sample) for VP72 targets with no observed cross-reactivity against nine common swine pathogens, demonstrating 100% analytical sensitivity and specificity during in-house testing and 90% and 92% analytical sensitivity and specificity respectively in an external laboratory evaluation. The complete assay was performed within 60 minutes using a portable heating and imaging platform. Together, these results demonstrate a simple, DNA extraction-free molecular diagnostic approach that enables rapid and reliable ASFV detection from whole blood applicable to field-relevant conditions.
Raut, B., Palla, G., Rafiq, N., Wang, J., Kumar, V., Kamel, M. S., Nguyen, D. V., Lanka, S., Maddox, C. W., Ragland, D., Pasternak, J. A., Verma, M. S.
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