# Establishment and Application of PDCoV Antibody Indirect ELISA Detection Method Based on N Protein

## TL;DR

Researchers developed a reliable blood test to detect antibodies against a new pig virus, PDCoV, which helps monitor and control its spread in swine farms.

## Contribution

A novel ELISA method using the PDCoV nucleocapsid protein was developed with high sensitivity and specificity for antibody detection.

## Key findings

- The ELISA method showed 96.67% sensitivity and 85.51% specificity with no cross-reactivity to other pig viruses.
- Testing 600 pig serum samples revealed significant regional and yearly variation in PDCoV antibody levels.
- The assay is reproducible with a coefficient of variation (CV) less than 10%.

## Abstract

A newly emerged pig virus, porcine deltacoronavirus (PDCoV), poses a serious threat to swine farms worldwide. To help control its spread, we developed a novel, efficient blood serum test to detect if a pig has been infected. This test works by identifying antibodies against the virus in a pig’s blood. Our method is confirmed to be accurate and did not confuse PDCoV with other viruses causing pig diarrhea. By testing 600 pig serum samples within Zhejiang Province over four years, we found that the infection rates varied significantly between different areas and from year to year. This new test provides a rapid and reliable tool for veterinarians and farmers to monitor the virus, helping to protect pig herds and support the swine industry.

Porcine deltacoronavirus (PDCoV) is a newly discovered porcine intestinal coronavirus that can pose a significant threat to the global commercial swine industry. We established an enzyme-linked immunosorbent assay (ELISA) detection method for the detection of PDCoV antibodies, based on the recombinant nucleocapsid (N) protein expressed using a baculovirus system. The assay was validated using positive and negative serum samples obtained from experimentally immunized rabbits and demonstrated an absence of cross-reactivity with either transmissible gastroenteritis virus (TGEV) or porcine epidemic diarrhea virus (PEDV). The recombinant PDCoV N protein antigen dilution (0.8 μg/mL), sample serum (1:400), and the enzyme-labeled secondary antibody (1:50) were used in this assay. The cut-off value was 0.355, without cross-reactivity including TGEV and PEDV. The ELISA method shows good sensitivity (96.67%), specificity (85.51%), and reproductivity (CV < 10%). We utilized the method to detect PDCoV antibodies in 600 pig serums collected from Zhejiang Province in the last four years (2021–2024). The results showed significant differences in antibody levels between regions and considerable fluctuation in positivity rates across the four-year period. As shown in the results, we developed a sensitive and specific ELISA method for detecting anti-PDCoV N antibodies, which provides a rapid and reliable diagnostic tool for PDCoV surveillance and control. This assay demonstrates significant potential for both epidemiological investigations and commercial applications in swine disease management.