Body temperatures, virus load and acute phase proteins after challenge infection of pigs vaccinated with VSVΔG(GP5/M) or with VSV*ΔG as control. Two groups of 5 SPF pigs each were vaccinated three times with 28 and 35 days interval, with 107 PFU/pig of VSVΔG(GP5/M) or of VSV*ΔG as mock control, respectively. 4 weeks after the 3rd vaccination, the pigs were infected intranasally with 106 PFU/pig of the homologous Olot/91 virus. The body temperatures A, B are shown for the individual animals. Blood was collected at the indicated days after infection. PRRSV load in serum was determined by real-time RT-qPCR (C) and by virus titration in MARC-145 cells (D), and the values expressed in 45-Cq and TCID50/mL serum (detection limit 1.7 log10 TCID50/mL), respectively. The serum concentrations (µg/mL) of the porcine acute phase proteins CRP (E) and Hp (F) were determined by ELISA. The data of panels C–F represent the mean of five pigs per group, with error bars representing the standard deviation (SD).