PRRSV infection kinetics in PK15S1–CD163 and PK15S10–CD163 cells. Cells were inoculated with PAM-grown PRRSV strains (LV, Lena, VR-2332 and MN-184). After 0, 12, 24, 48 and 72 h of infection, cells were fixed and an immunofluorescence staining was performed (A). The number of infected cells was counted and expressed as percentage of infected cells (B). In addition, the virus titers in supernatants were determined. The blue line represents the kinetics of the virus infection rate/titers in PK15S1–CD163 cells, while the red line represents the kinetics of the virus infection rate/titer in PK15S10–CD163 cells. G1s1 = genotype 1 subtype 1; G1s3 = genotype 1 subtype 3; G2 = genotype 2; S1 = PK15S1–CD163, S10 = PK15S10–CD163. Value of titers and infection proportion presented on the curve graph represent mean ± SD of three experiments. Scale bar: 200 µm.