Fig. 5. Detection of porcine reproductive and respiratory syndrome virus (PRRSV)-specific antibodies at different times after infection. Six pigs in two groups (three pigs each) were inoculated with two prototype PRRSVs (VR2332 and Lelystad virus [LV]) and sera were collected at 0, 1, 3, 5, 7, and 14 days post-infection (dpi). The immunochromatographic strip test (ICST) could detect PRRSV-specific antibody in 1 of 6 pigs at 3 dpi, 2 of 6 pigs at 5 dpi, and all pigs at 7 dpi, while the commercial enzyme-linked immunosorbent assay (ELISA) detected PRRSV-specific antibody in only 1 of 6 pigs (Pig 3) at 7 dpi. All pigs were positive for PRRSV-specific antibodies in both ELISA and ICST results from 14 dpi onwards (data not shown). Samples with time-resolved fluorescence reader test intensities ≥ 40 were considered positive; samples with sample-to-positive (S/P) ratios ≥ 0.4 were considered positive.
