Fig. (4) Serum immune cytokine profiles after PRRSV infection. Cytokine expression profiles in the sera (A) of challenge pigs 6 days post infection (DPI) and supernatants of lung homogenates (B) were tested by quantitative ELISA. Data were shown as mean ± SEM for 5 pigs per group. One asterisk denotes a statistically significant difference (P <0.05), and “NS” denotes there was no statistically significant difference.