Fig. 3

Sensitivity, specificity and stability of two cELISA using the g1-2-PRRSV-Nb3-HRP and g1-PRRSV-Nb136-HRP fusion proteins as reagents, respectively. A Specificity analysis of g1-cELISA to detect antibodies against swine viruses. B Specificity analysis of g1-2-cELISA to detect antibodies against swine viruses. C Serum samples from five challenged SPF pigs with SD16 strains were detected using g1-2-cELISA and g1-cELISA. D Serum samples from five challenged SPF pigs with NADC30-like strains were detected using g1-2-cELISA and g1-cELISA. E Serum samples from six challenged SPF pigs with GZ11-G1 strains were detected using g1-2-cELISA and g1-cELISA. F Determination of the largest dilution of positive pig serum samples for anti-PRRSV-1 and -2 antibodies. G Stability analysis of the two cELISA using direct ELISA to determine the nanobody-HRP fusion protein still binding to the coated plates at different times. H Stability analysis of the two cELISA to still detect the positive pig sera for PRRSV. The coated ELISA plates with PRRSV-1-N protein and nanobody-HRP fusion proteins were stored at 4ºC for 1, 2, 3, 4, 5, 6, 7 and 8 months. Statistical analysis was performed using GraphPad Prism V. 9.0. Comparisons between groups were considered statistically significant at P < 0.05