Detection of ongoing asymptomatic Porcine deltacoronavirus infections via transiently produced IgGs using...

Asymptomatic hosts can shed pathogens without showing clinical symptoms, making them invisible to routine screenings and potent drivers of pathogen dissemination and epidemic outbreaks. The lack of reliable, cost-effective tools for large-scale identification of asymptomatic infections hampers early intervention and control strategies. Porcine deltacoronavirus (PDCoV), a zoonotic pathogen with potential for cross-species transmission, presents a critical case for improving such detection methodologies.

We improved the IgG serodynamics-based epitope discovery method by integrating clustering and high-level analysis, which helped us identify linear epitopes with immunogenicity from a large number of candidate epitopes. Epitopes were filtered using negative sera identified by virus neutralization tests (VNT) to eliminate highly antigenic probes. These remaining low antigenicity probes were used to construct a protein-peptide hybrid microarray (PPHM_PDCoV). The platform was applied to detect PDCoV-specific transiently produced IgGs (TPIs) in serum samples collected from pigs aged 28-174 days.

The PPHM_PDCoV successfully detected asymptomatic PDCoV infections in pigs, particularly showing a peak infection rate of 15% at 45 days of age. The platform enabled not only the detection of asymptomatic carriers but also the characterization of infection stages.

The study provides a novel, specific, and practical platform for detecting asymptomatic PDCoV infections based on serological TPI signatures. It offers early warning and disease prevention strategies in livestock and establishes a framework for future monitoring of potential interspecies transmission.