Infection of PCLS by BPIV3, BRSV-GFP and BHV-1-GFP. PCLS were mock-infected or infected by any of the three viruses (105 FFU/mL). Up to 7 dpi, virus release into the supernatants was determined by titration on Vero (BRSV-GFP) or MDBK (BPIV3, BHV-1-GFP) cells. Experiments were performed with samples from 3 animals in duplicate. Indicated are mean values + standard deviation. The detection limit was set to 40 FFU.