Identification of a novel linear B-cell epitope in porcine deltacoronavirus nucleocapsid protein

• Published in: Applied microbiology and biotechnology 2023-02, Vol.107 (2-3), p.651-661
• Main Authors: He, Wei, Shi, Xinze, Guan, Haifei, Zou, Yuntong, Zhang, Shengkun, Jiang, Zhiwen, Su, Shuo
• Format: Article
• Language: English
• Subjects: Amino acid sequence; Amino acids; Animals; Antibodies, Monoclonal; Antigenic determinants; Antigenicity; B cells; Biomedical and Life Sciences; Biotechnological Products and Process Engineering; Biotechnology; Causes of; Conserved sequence; Coronaviridae; Coronavirus - genetics; Coronavirus infections; Coronavirus Infections - veterinary; Coronaviruses; COVID-19; Deltacoronavirus - genetics; Diarrhea; Diseases; Epitopes; Epitopes, B-Lymphocyte - genetics; Genetic aspects; Homology; Identification and classification; Life Sciences; Lymphocytes B; Microbial Genetics and Genomics; Microbiology; Monoclonal antibodies; N protein; Neonates; Nucleocapsid Proteins - genetics; Nucleocapsid Proteins - metabolism; Nucleocapsids; Physiological aspects; Polypeptides; Proteins; Swine; Swine Diseases; Viral proteins; Vomiting; Western blotting
• ISSN: 0175-7598; 1432-0614; 1432-0614
• DOI: 10.1007/s00253-022-12348-5

Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus that caused diarrhea and/or vomiting in neonatal piglets worldwide. Coronaviruses nucleocapsid (N) protein is the most conserved structural protein for viral replication and possesses good antigenicity. In this study, three monoclonal antibodies (mAbs), 3B4, 4D3, and 4E3 identified as subclass IgG2aκ were prepared using the lymphocytic hybridoma technology against PDCoV N protein. Furthermore, the B-cell epitope recognized by mAb 4D3 was mapped by dozens of overlapping truncated recombinant proteins based on the western blotting. The polypeptide 28 QFRGNGVPLNSAIKPVE 44 (EP-4D3) in the N-terminal of PDCoV N protein was identified as the minimal linear epitope for binding mAb 4D3. And the EP-4D3 epitope’s amino acid sequence homology study revealed that PDCoV strains are substantially conserved, with the exception of the Alanine 43 substitution Valine 43 in the China lineage, the Early China lineage, and the Thailand, Vietnam, and Laos lineage. The epitope sequences shared high similarity (94.1%) with porcine coronavirus HKU15-155 (PorCoV HKU15), Asian leopard cats coronavirus (ALCCoV), sparrow coronavirus HKU17 (SpCoV HKU17), and sparrow deltacoronavirus. In contrast, the epitope sequences shared a very low homology (11.8 to 29.4%) with other porcine CoVs (PEDV, TGEV, PRCV, SADS-CoV, PHEV). Overall, the study will enrich the biological function of PDCoV N protein and provide foundational data for further development of diagnostic applications. Key points • Three monoclonal antibodies against PDCoV N protein were prepared. • Discovery of a novel B-cell liner epitope ( 28 QFRGNGVPLNSAIKPVE 44 ) of PDCoV N protein. • The epitope EP-4D3 was conserved among PDCoV strains.