FIG 7.

Comparison of IFN-α production levels and NK cell cytotoxicity in pigs inoculated with the WT virus and nsp1β mutants. Pigs were uninfected (mock) or infected with WT PRRSV (WT) or the three indicated mutants (vR128A, vR129A, and vRR129AA). (A) Lung samples collected at 7 dpi were used to prepare lung lysates, and IFN-α levels were analyzed by an ELISA. (B and C) PBMCs (NK effectors) were harvested on the day of necropsy (7 dpi), and cells were cocultured with target cells (K562) at an E:T ratio of 100:1 (B) or 50:1 (C). After overnight incubation, the NK cell-specific cytotoxic activity was determined by flow cytometry. Each data point represents the mean value ± SEM of data from 3 pigs. Statistical significance between the wild-type virus-infected group and mutant virus-infected groups was determined by one-way ANOVA and Tukey's test.