Characterization of Two Monoclonal Antibodies That Recognize Linker Region and Carboxyl Terminal Domain of Coronavirus Nucleocapsid Protein

The transmissible gastroenteritis virus (TGEV) nucleocapsid (N) protein plays important roles in the replication and translation of viral RNA. The present study provides the first description of two monoclonal antibodies (mAbs) (5E8 and 3D7) directed against the TGEV N protein linker region (LKR) and carboxyl terminal domain (CTD). The mAbs 5E8 and 3D7 reacted with native N protein in western blotting and immunofluorescence assay (IFA). Two linear epitopes, (189)SVEQAVLAALKKLG(202) and (246)VTRFYGARSSSA(257), located in the LKR and CTD of TGEV N protein, respectively, were identified after truncating the protein and applying a peptide scanning technique. Using mAb 5E8, we observed that the N protein was expressed in the cytoplasm during TGEV replication and that the protein could be immunoprecipitated from TGEV-infected PK-15 cells. The mAb 5E8 can be applied for different approaches to diagnosis of TGEV infection. In addition, the antibodies represent useful tools for investigating the antigenic properties of the N protein.