Development of a One-Step Immunochromatographic Strip Test for Rapid Detection of Antibodies Against Classic Swine Fever

An immunochromatographic strip (GICA strip) was developed for the simple and rapid detection of antibodies against classical swine fever virus (CSFV). In the GICA strip, the expressed protein of E2 was labeled with colloidal gold and was used as the detector, and the staphylococcal protein A (SPA) and swine antibody against CSFV blotted on the nitrocellulose membrane were used for the test and control lines, respectively. Conjugation of E2 protein with colloidal gold was optimal at 5.25 μg of protein per mL of colloidal gold. The optimum concentration of the E2 protein applied at the test line was 1.5 mg/mL. The GICA strip was specific for antibodies against CSFV, produced negative results with sera from noninfected pigs or other animals, and was as sensitive or nearly as sensitive as ELISA and HI. According to the comparison of GICA strips with IDEXX ELISA kits, the coincidence rate was 93.26 %. The strips produced results within 5–15 min and can be stored at 4 °C for 3 years or 37 °C 1 year. The strip can be useful for both country veterinarians and field epidemiologists.