FIG. 5.

Reduction of replication of 07V063 (A), or 08V204 (B), in PAM by serum antibodies against peptides RVTAAQGRIYTR and RTNTTQGKVPSQ, respectively. A single replication virus-neutralization test with homologous virus was performed with a 1:2 dilution series (500–16 μg/mL) of epitope-specific serum antibodies, purified from polyclonal serum by peptide affinity chromatography. Protein A purified immunoglobulins of a PRRSV-negative pig were included as mock antibodies (open symbols). The number of infected cells for each antibody dilution was set relative to the mean number of infected cells for all mock conditions within one experiment. The means and standard deviations of three experiments were calculated and are given in the graphs. Statistically significant differences (*p < 0.01) were observed with RVTAAQGRIYTR-specific antibodies, compared to mock antibodies, for antibody concentrations between 500 and 31 μg/mL in the test with virus strain 07V063. In the test with virus strain 08V204, statistically significant differences (*p < 0.01) were observed with RTNTTQGKVPSQ-specific antibodies, compared to mock antibodies, for antibody concentrations between 500 and 16 μg/mL.