Fig. 2.

Rescue and passage of PRRSV. (A) MARC-145 cells were transfected with in vitro transcripts derived from pFL12Pol⁻ or pFL12, or with total RNA from cells infected with parental virus. At 2 days posttransfection, cells were examined for expression of N protein by immunofluorescence. (B) Supernatants from parallel cultures of transfected cells were collected 2 days posttransfection, clarified, and passaged onto naïve MARC-145 cells. Forty-eight hpi, the cell monolayer was examined for expression of N protein as before. Cells in panel B were photographed at higher magnification than in panel A.