FIG. 5.

The extracellular form of GP₃ (sGP₃) is also generated during PRRSV infection of MARC-145 cells. Mock-infected or IAF-Klop-infected MARC-145 cells (3 × 10⁷ cells infected at a MOI of 10) were radiolabelled for 12 h. The culture medium was then clarified at 100,000 × g for 2 h in order to pellet the virus and was used for immunoprecipitation with α3 antiserum. For comparison, 293 cells (3 × 10⁷) were similarly infected with AdCMV5/ORF3 virus (MOI of 20 to 30) and the culture medium was used for radioimmunoprecipitation and SDS-PAGE analysis. Numbers on the right indicate the positions and sizes of ¹⁴C-radiolabelled marker proteins.