FIG 6.

Comparison of viral loads in BALF and lung samples from 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). Lungs harvested on the day of necropsy (7, 21, and 35 dpi) were used for collecting BALF and lung lysates. (A and B) Viral loads in BALF (A) and lung lysate (B) samples were quantified by quantitative RT-PCR and calculated as viral RNA copies per milliliter of BALF or viral RNA copies per gram of lung. (C and D) Infectious virus titers in BALF (C) and lung lysate (D) samples were determined by a microtitration assay and calculated as log TCID₅₀ per milliliter or log TCID₅₀ per gram. A key explaining the treatment groups in panels B to D is given in panel A. Statistical significance between the wild-type virus-infected group and mutant virus-infected groups was determined by one-way ANOVA and Tukey's test and is indicated with asterisks (**, P < 0.01).