Table 1

Amplification primers for truncated and deleted mutant genes"

Table 2

Names and GenBank accession numbers of virus strains"

Fig. 1

Identification of the 6E8 monoclonal antibody (MAb) epitope A. Diagram of N protein truncation; B. Expression analysis of B1 and B2 protein by SDS-PAGE (M. Protein molecular weight marker; 1. B1 pro-induced products; 2. B1 induced products; 3. B2 pro-induced products; 2. B2 induced products); C. Expression analysis of C1 and C2 protein by SDS-PAGE (M. Protein molecular weight marker; 1. C1 pro-induced products; 2. C1 induced products; 3. C2 pro-induced products; 4. C2 induced products); D. Expression analysis of D1, D2 and D3 protein by SDS-PAGE (M. Protein molecular weight marker; 1. D1 pro-induced products; 2. D1 induced products; 3. D2 pro-induced products; 4. D2 induced products; 5. D3 pro-induced products; 6. D3 induced products); E. Expression analysis of E protein by SDS-PAGE (M. Protein molecular weight marker; 1. E pro-induced products; 2. E induced products); F. Expression analysis of F protein by SDS-PAGE (M. Protein molecular weight marker; 1. F pro-induced products; 2. F induced products); G. The reactivity of the mAb 6E8 with the B1 and B2 protein was identified by Western blot (M. Protein molecular weight marker; 1. The B1 protein; 2. The B2 protein); H. The reactivity of the mAb 6E8 with the C1 and C2 protein was identified by Western blot (M. Protein molecular weight marker; 1. The C1 protein; 2. The C2 protein); I. The reactivity of the mAb 6E8 with the D1, D2 and D3 protein was identified by Western blot (M. Protein molecular weight marker; 1. The D1 protein; 2. The D2 protein; 2. The D3 protein); J. The reactivity of the mAb 6E8 with the E and F protein was identified by Western blot (M. Protein molecular weight marker; 1. The E protein; 2. The F protein). The red box indicates where the protein is expressed"

Fig. 2

Alignment of identified epitope in SADS-CoV N protein Epitope regions of 69-74 aa recognized by the MAb 6E8 are circled with red. Black dots indicate residues that are exact match"

Fig. 3

The specific identification of the MAb 6E8 A. Identification of the recognizing 6E8 and bat coronavirus HKU2 N protein (M. Protein molecular weight marker; pEGFP-C2. Empty plasmid control; pEGFP-C2-HKU2-N. Recombinant plasmid; Anti-6E8. The specific monoclonal antibody of SDS-CoV N protein; Anti-EGFP. EGFP labeled antibody; Anti-β-actin. Internal reference antibody); B. Identification of the 6E8 reactivity with SADS-CoV, PEDV, and TGEV (1. Huh7 mock-infected SADS-CoV; 2. Huh7 infected SADS-CoV; 3. Vero E6 mock-infected PEDV; 4. Vero E6 infected PEDV; 5. PK1 mock-infected TGEV; 6. PK1 infected TGEV. M. Protein molecular weight marker; Anti-6E8. The specific monoclonal antibody of SDS-CoV N protein; Anti-β-actin. Internal reference antibody)"

Fig. 4

The MAb 6E8 promotes SADS-CoV infection in Huh7 A. The effect of the mAb 6E8 on the replication of SADS-CoV was verified by IFA; B. Western blot analysis of the changes in SADS-CoV N protein expression after treatment with 6E8 (1. Huh7 cells control; 2-5. The cells were treated with 1, 2, 4, and 8 μg·mL-1 irrelevant antibody, respectively; 6-9. The cells were treated with 1, 2, 4, and 8 μg·mL-1 6E8, respectively; Anti-6E8. The specific monoclonal antibody of SDS-CoV N protein; Anti-GAPDH. Internal reference antibody); C. Densitometric analysis of N protein expression (The ratio of N protein to GAPDH was calculated based on the gray value, the ratio of N to GAPDH was normalized to the isotype control, set to 1); D. The change of copy number of SADS-COV after the mAb 6E8 treatment was detected by qPCR; E. The change of virus titer of SADS-COV after the mAb 6E8 treatment (in Fig. C-E, Isotype control. Negative control. 6E8. The specific monoclonal antibody of SDS-CoV N protein) *. P < 0.05, **. P < 0.01, ***. P < 0.001; ****. P < 0.000 1, ns. P>0.05"