FIGURE LEGENDS
FIGURE 1 . Comparison of antigenic index profiles of the N-terminal domain (aa 1-380) of the S protein between PEDV genotype 1 CV777 vaccine strain and genotype 2 CH/ZMDZY/11 strain. Antigenic index was calculated using Protean of DNAStar Lasergene under the Jameson-Wolf method. The corresponding alignment of amino acid sequences and positions of the two regions containing amino acid mutations, deletions, and insertions are shown. Mismatched amino acids are marked in red. Insertions are marked in blue and italic. Deletions are indicated by dashes. The predicated N-linked glycosylation sites are underlined.
FIGURE 2 . Expression and purification of recombinant N-terminal domain (NTD) of S protein of G1 and G2 PEDV strain. M. Protein Marker; 1. pET28a-G2-NTD/BL21 uninduced; 2. pET28a-G2-NTD/BL21 induced; 3. Purified G2-NTD protein; 4. pET28a-G1-NTD/BL21 uninduced; 5. pET28a-G1-NTD/BL21 induced; 6. Purified of G1-NTD protein
FIGURE 3. Western blot analysis of cross-reactivity of antibodies against G1 and G2 PEDV S proteins (A) Same amount of recombinant G1-NTD and G2-NTD was loaded onto SDS-PAGE gel; (B) G1-NTD antisera was used as the primary antibody; (C) G2-NTD antisera was used as the primary antibody.
FIGURE 4 . ELISA analysis of cross-reactivity of antibodies against G1 and G2 PEDV S proteins. (A) G1-NTD antisera was used as the primary antibody; (B) G2-NTD antisera was used as the primary antibody.
FIGURE 5. Evaluation of cross-reactivity of antibodies against G1 and G2 PEDV strain by indirect immunofluorescence assay. Vero cell monolayers were infected with the PEDV G1 CV777 vaccine strain and G2 CH/ZMDZY/11 strain, respectively. At 36 h postinfection, cytopathic effects were recorded and cells were examined by IFA using anti-S antibodies. G1-NTD antisera (B and F) and G2-NTD antisera (D and H) were used as the primary antibody, respectively. All images were taken at a 100-fold magnification. The syncytia induced by the CH/ZMDZY/11 (E to H) were indicated by arrows.
FIGURE 6 . Foci staining in Vero cell infected with PEDV G1 CV777 vaccine strain and G2 CH/ZMDZY/11 strain by using IPMA in focus reduction neutralization assay. At 36 h postinfection, foci were detected by IPMA using anti-S antibodies as the primary antibody and HRP-labelled anti-mouse IgG as the secondary antibody.
FIGURE 7. Evaluation of cross-neutralization of antibodies against G1 and G2 PEDV strain by focus reduction neutralization assay. (A) Cross-neutralization of G1-NTD antisera against G1 and G2 PEDV strains; (B) Cross-neutralization of G2-NTD antisera against G1 and G2 PEDV strains; Neg. Negative serum; blank. Medium control.
FIGURE 8. Reciprocal of PEDV neutralizing antibody titers of G1- and G2-NTD antisera against the CV777 vaccine and CH/ZMDZY/11 strains determined by focus reduction neutralization assay. The virus neutralization antibody titer of each serum was expressed as reciprocal of serum dilution giving 50% reduction in the number of focus forming unit. Values are representative of the mean from three independent experiments in the duplicate and error bars denote standard deviations.