A quantum dot-based double-antibody sandwich immunochromatographic strip for rapid detection of porcine deltacoronavirus targeting the nucleocapsid protein.

Publication date: Jan 01, 2026

Porcine deltacoronavirus (PDCoV) is an emerging enteropathogenic pathogen that causes severe diarrhea in suckling piglets and carries significant zoonotic spillover potential. Therefore, developing a rapid, sensitive, and specific diagnostic assay is crucial for effective PDCoV surveillance and control. Here, we developed a novel quantum dot-based immunochromatographic strip (QD-ICS) using a double-antibody sandwich format to detect the PDCoV nucleocapsid (N) protein. The strip employs QD-conjugated mouse anti-PDCoV-N monoclonal antibody (mAb) as the detection probe and rabbit anti-PDCoV-N polyclonal antibody as the immobilized capture antibody. Through systematic optimization, we determined the ideal parameters: 20 μL of QD solution activated with 300 μL 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, 60 μg mAb coupling at pH 7. 0, and a conjugate spraying density of 5 μL/cm. The QD-ICS achieved optimal performance with 1. 75 mg/mL polyclonal antibody on the test line and 1 mg/mL goat anti-mouse IgG on the control line. The strip exhibited high specificity without cross-reactivity with porcine epidemic diarrhea virus, transmissible gastroenteritis virus, porcine enteric alphacoronavirus, porcine rotavirus, porcine parvovirus, etc. It achieved a 95 % detection limit of 236. 661 TCID/mL for PDCoV and maintained stable performance throughout six months of storage at 25 ^0C and 37 ^0C. Both intra- and inter-batch coefficients of variation for PDCoV detection were below 10 %, confirming good reproducibility. In clinical validation with 60 porcine rectal swabs, the QD-ICS showed 96. 7 % concordance with reference real-time RT-PCR results. Offering comparable clinical performance, our QD-ICS detects faster than real-time RT-PCR and requires neither expensive equipment nor specialized training, making it an ideal field-deployable diagnostic tool.

Semantics

Original Article