PCV2 genomic DNA copies in spleen tissues of PCV2-infected LW and YL pigs. The PCV2 genomic DNA copies in spleen were measured through absolute qPCR. Multiplying the value on the Y-axis by 106 indicates the copy number of PCV2 genomic DNA in 1 g of spleen tissue. Data are represented as the mean value ± SE of three experiments. ***Indicates significance at the P value threshold level of 0.001.