[A colloidal gold test strip assay for antibody detection based on the VP7 protein of epizootic hemorrhagic disease virus].

To establish a rapid method for detecting antibodies against epizootic hemorrhagic disease virus (EHDV), the highly conserved group-specific protein VP7 was used as the target antigen in this study. The recombinant VP7 protein was expressed in Sf9 cells using a baculovirus expression system and subsequently purified. Polyclonal antibodies were generated by immunizing New Zealand white rabbits with the purified recombinant VP7 protein. Western blotting and cellular immunofluorescence assays confirmed the strong immunogenicity of the protein. A colloidal gold-based immunochromatographic test strip for detecting anti-EHDV antibodies was developed by conjugating recombinant streptococcal protein G with colloidal gold nanoparticles. The control line was coated with rabbit anti-streptococcal protein G antibody, while the test line was coated with the purified recombinant VP7 protein. Performance evaluation indicated that the test strip possessed desirable sensitivity, specificity, reproducibility, and stability. No cross-reactivity was observed with positive sera from animals infected with bluetongue virus, sheep pox virus, orf virus, peste des petits ruminants virus, foot-and-mouth disease virus, or lumpy skin disease virus. Testing of 200 clinical serum samples demonstrated a 97% coincidence rate between this test strip and a commercial competitive ELISA assay kit for EHDV antibody detection, with a Kappa value of 0.88. This study provides technical support for the rapid diagnosis of EHDV infection and contributes to disease surveillance and control.