Development of a Colloidal Gold Immunochromatographic Test Strip for PPRV Antibody Detection Based on Antigenic Epitope-Derived Recombinant Protein

Peste des petits ruminants virus (PPRV) causes a highly fatal disease that severely impacts small ruminant production and global food security. This study aimed to develop a rapid, user-friendly colloidal gold immunochromatographic test strip for detecting PPRV-specific antibodies using a double-antigen sandwich format. Bioinformatic analysis using DNASTAR Protean was performed to predict candidate antigenic regions in the PPRV H and N proteins. Three predicted candidate regions from each protein were selected and incorporated into the design of the recombinant fusion antigen PPRV-H3N3EP. The recombinant antigen was expressed in E. coli, purified, and refolded to obtain a final concentration of 8.52 mg/mL. The strip was assembled with colloidal gold-labeled fusion protein as the detection probe and unlabeled protein coated on the test line, plus an independent mouse IgG/goat anti-mouse IgG control system. Performance evaluation showed that the results were readable within 10–15 min. The strip showed satisfactory analytical sensitivity and cross-reactivity performance, consistent qualitative results in within-batch repeatability testing, and preliminary short-term storage stability. In a comparative evaluation using sheep serum samples and a commercial competitive enzyme-linked immunosorbent assay (ELISA) kit, the overall agreement reached 97.9%. Collectively, the constructed PPRV-H3N3EP antigen enabled a simple, rapid, and reliable strip assay suitable for field detection of PPRV antibodies and post-vaccination monitoring, while also providing a methodological reference for developing antibody tests for other pathogens.