FIG 7.

Rescuing of an EGFP-labeled rISAV. RNA was extracted from the supernatants from the first to fourth passages (P1 to P4) of rISAV^S6/EGFP-HPR propagated in ASK cells for 7 days postinfection and analyzed with RT-PCR to detect chimeric vRNA utilizing specific primers (Table 2). vRNA was amplified for the EGFP gene only (left), segment 6 only (middle), or the chimeric region containing part of both segment 6 and EGFP (right). Controls include a sample lacking RNA (H₂O) and RNA obtained from mock transfection, which corresponds to untransfected ASK cells. ISAV_901_09 corresponds to ASK cells infected with the WT ISAV 901 strain, and rISAV^S6/EGFP-HPR corresponds to supernatants from ASK cells infected with rISAV^S6/EGFP-HPR for four sequential blind passages. Experiments were performed two times with similar results.