Viremia and viral loads in tissue assessment
To determine the duration of viremia and viral loads in different tissues after treatment with the SD-R vaccine strain, serum samples collected at dpv 0, 7, 14, 21, and 28 and dpi 3, 5, 7, 10, 14, and 21 and ten tissues of all the piglets were used to detect the RNA copy number of PRRSV by TaqMan®-based real-time fluorescence quantitative RT–PCR (Wei et al., 2008).