Ag-rich Ag-Au nanoshells based lateral flow immunoassay for rapid and sensitive detection of bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) is a key member of the genus Pestivirus, which can cause persistent infections (PI) characterized by immunotolerance, leading to significant economic losses to the cattle industry globally. Among the detection methods for BVDV, conventional gold nanoparticles-based lateral flow immunoassay (Au NPs-based LFIA), which uses gold nanoparticles as signal reporters, often suffers from low sensitivity due to insufficient signal brightness. The development of more sensitive point-of-care testing (POCT) methods is urgently needed. In the present study, we developed a novel signal reporter based on Ag-rich Ag-Au nanoshells (AgR-Au NSs) featuring enhanced visual color brightness. The developed AgR-Au NSs-based LFIA enables one-step BVDV detection within 20 minutes. Under optimized conditions, the visual detection limit reached 1.95 × 103TCID50/mL, a four-fold improvement over conventional Au NPs-based LFIA and consistent with ELISA. The assay showed broad reactivity across different BVDV genotypes, no cross-reactivity with other pathogens, and good stability (4 °C for 180 days). In 215 clinical samples, it achieved 98.14% concordance with the commercial ELISA kit. In general, the AgR-Au NSs-based LFIA provides a sensitive, specific POCT tool for BVDV field testing and holds promise for broader application of AgR-Au NSs in infectious disease diagnostics.