FIG. 1.
Anti-PRV IgG1 subclass in serum. The anti-PRV IgG1 subclass was determined by indirect enzyme-linked immunosorbent assay using microtitration plates coated with PRV antigen. The mean titers, including standard error bars, for each group of pigs are expressed in the log10 of the highest serum dilution giving an optical density value of more than three times the optical density of a pool of control serum from unvaccinated pigs. *, P < 0.05; **, P < 0.01, calculated with the nonparametric Mann-Whitney test; #, no survivor.