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The outbreak of African Swine Fever (ASF) has caused huge economic losses to the pig industry. There are no safe and effective vaccines or diagnostics available. The p30 protein serves as a key target for the detection of ASFV antibodies and is an essential antigenic protein for early serological diagnosis. Here, the p30 protein was purified after being expressed in E. coli and its immunogenicity was verified in sera from pigs naturally infected with ASFV. Furthermore, a monoclonal antibody (McAb) designated as McAb 1B4G2–4 (subtype IgG1/kappa-type) was produced and it was verified to specifically recognize the ASFV Pig/HLJ/2018/strain and eukaryotic recombinant ASFV p30 protein. The epitope identified by McAb 1B4G2–4, defining the unique B-cell epitope 164HNFIQTI170, was located using peptide scanning. Comparing amino acid (aa) sequence revealed that this epitope is conserved in all reference ASFV strains from different regions of China, including the highly pathogenic strain Georgia 2007/1 (NC_044959.2) that is widely distributed. It is also exposed to the surface of the p30 protein, suggesting that it could be an important B-cell epitope. Our study may serve as a basis for the development of serological diagnostic methods and subunit vaccines.

African Swine Fever (ASF), caused by the African swine fever virus (ASFV), has inflicted significant economic losses on the pig industry in China. The key to mitigating its impact lies in accurate screening and strict biosecurity measures. In this regard, the development of colloidal gold immunochromatographic test strips (CGITS) has proven to be an effective method for detecting ASFV antibodies. These test strips are based on the ASFV p30 recombinant protein and corresponding monoclonal antibodies. The design of the test strip incorporates a high-concentration colloidal gold-labeled p30 recombinant protein as the detection sensor, utilizing Staphylococcal Protein A (SPA) as the test line (T line), and p30 monoclonal antibody as the control line (C line). The sensitivity and specificity of the test strip were evaluated after optimizing the labeling concentration, pH, and protein dosage. The research findings revealed that the optimal colloidal gold labeling concentration was 0.05 %, the optimal pH was 8.4, and the optimal protein dosage was 10 μg/mL. Under these conditions, the CGITS demonstrated a detection limit of 1:512 dilution of ASFV standard positive serum, without exhibiting cross-reactivity with antibodies against other viral pathogens. Furthermore, the test strips remained stable for up to 20 days when stored at 50 °C and 4 °C. Comparatively, the CGITS outperformed commercial ELISA kits, displaying a sensitivity of 90.9 % and a specificity of 96.2 %. Subsequently, 108 clinical sera were tested to assess its performance. The data showed that the coincidence rate between the CGITS and ELISA was 93.5 %. In conclusion, the rapid colloidal gold test strip provides an efficient and reliable screening tool for on-site clinical detection of ASF in China. Its accuracy, stability, and simplicity make it a valuable asset in combating the spread of ASF and limiting its impact on the pig industry.

Copyright of Chinese Journal of Preventive Veterinary Medicine / Zhongguo Yufang Shouyi Xuebao is the property of Chinese Journal of Preventive Veterinary Medicine Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The full identification of ASFV's antigenic epitopes is essential for the creation of targeted serological assays and the development of efficacious subunit vaccines. • The p30 protein is capable of producing neutralizing antibodies. • The monoclonal antibody specifically recognized transiently expressed p30 protein and the inactivated ASFV Pig/HLJ/2018 strain. • The monoclonal antibody against p30 protein recognized a novel linear and immunodominant epitope. • These findings may serve as a basis for the development of serological diagnostic methods and subunit vaccines. The outbreak of African Swine Fever (ASF) has caused huge economic losses to the pig industry. There are no safe and effective vaccines or diagnostics available. The p30 protein serves as a key target for the detection of ASFV antibodies and is an essential antigenic protein for early serological diagnosis. Here, the p30 protein was purified after being expressed in E. coli and its immunogenicity was verified in sera from pigs naturally infected with ASFV. Furthermore, a monoclonal antibody (McAb) designated as McAb 1B4G2–4 (subtype IgG1/kappa-type) was produced and it was verified to specifically recognize the ASFV Pig/HLJ/2018/strain and eukaryotic recombinant ASFV p30 protein. The epitope identified by McAb 1B4G2–4, defining the unique B-cell epitope 164HNFIQTI170, was located using peptide scanning. Comparing amino acid (aa) sequence revealed that this epitope is conserved in all reference ASFV strains from different regions of China, including the highly pathogenic strain Georgia 2007/1 (NC_044959.2) that is widely distributed. It is also exposed to the surface of the p30 protein, suggesting that it could be an important B-cell epitope. Our study may serve as a basis for the development of serological diagnostic methods and subunit vaccines. [ABSTRACT FROM AUTHOR]