Development and Preliminary Application of a Colloidal-Gold Dual Immunochromatography Strip for Detecting African Swine Fever Virus Antibodies

African swine fever (ASF) is an acute and highly contagious infectious disease caused by the African swine fever virus (ASFV). Currently, there is no vaccine against ASF worldwide, and no effective treatment measures are available. For this reason, developing a simple, rapid, specific, and sensitive serological detection method for ASFV antibodies is crucial for the prevention and control of ASF. In this study, a 1:1 mixture of gold-labeled p30 and p72 probes was used as the gold-labeled antigen. The p30 and p72 proteins and their monoclonal antibodies were coated on a nitrocellulose membrane (NC) as a test (T) line and control (C) line, respectively. A colloidal-gold dual immunochromatography strip (ICS) for ASFV p30 and p72 protein antibodies was established. The results showed that the colloidal-gold dual ICS could specifically detect ASFV antibodies within 5–10 min. There was no cross-reaction after testing healthy pig serum, porcine reproductive and respiratory syndrome virus (PRRSV), foot-and-mouth disease type A virus (FMDV-A), foot-and-mouth disease type O virus (FMDV-O), porcine circovirus type 2 (PCV-2), and swine fever (CSFV) positive sera. A positive result was obtained only for the positive control, P1. The sensitivity of the test strips was 1:256, which was equivalent to that of commercially available ELISA kits. Their coincidence rate with the two commercial ASFV ELISA antibody detection kits was higher than 98%. The test strips were stably stored at 18–25 °C and 4 °C for 4 and 6 months, respectively. The dual test strips prepared in this study had high sensitivity and specificity and were characterized by rapid detection, simple operation, and easy interpretation of results. Therefore, they are of great significance to diagnose, prevent, and control African swine fever.