CSFV-specific IgG responses with IgG subclass differentiation assessed by ELISA in serum from experimental groups. a) Results for the IgG1 subclass. (b) Results for the IgG2 subclass. (c) Results for the IgG1:IgG2 ratio. All samples were assessed the same day with positive and negative controls on each plate in order to check the sensitivity and the reproducibility of the assay. All data are reported as the mean (± SE) of OD with subtracted blank value, obtained for the 5 pigs in each group. *p < 0.05 compared each post-vaccination, post-challenge or post-infection value with its respective control value using the Mann–Whitney test. Dotted line with white triangles: CP7_E2alf vaccinated group (CP7 vacc); dotted line with white squares: C-strain vaccinated group (C vacc); dotted line with white circles: control group; full line with black triangles: CP7_E2alf vaccinated and challenged group (CP7 vacc & chal); full line with black squares: C-strain vaccinated and challenged group (C vacc & chal); full line with black circles: infected group.