Evolution of the humoral response (ELISA) against PRRSV in experiments 1 and 2.
2a. Average sample to positive (S/P) ratios of optical densities from day +15 to +84 post-inoculation. Empty bars correspond to pigs in experiment 1 (strain 3262: A); grey bars correspond to pigs in experiment 2 (strain 3267: B). Lines show results of control (un-inoculated pigs) in both experiments. 2b. Serological evolution (S/P ratios) of pigs in experiment 1 after the second challenge (84 pi). Empty bars correspond to the homologous challenge (group A + A), grey bars to the heterologous challenge (A + B) and black bars depict results of naïve pigs inoculated for the first time with strain 3267 (C1 + B) 2c. Serological evolution (S/P ratios) of pigs in experiment 2 after the second challenge (84 pi). Empty bars: (B + B); grey bars: B + A; black bars: naïve pigs inoculated for the first time with strain 3262 (C2 + A). In all cases, different superscript letters indicated statistically significant differences (p < 0.05) as determined in the Kruskal-Wallis test; n.s. = non-significant.