Construction of a full-length infectious SAV3 cDNA and recovery of infectious virus. (A) A cDNA fragment containing the EGFP ORF and 3'UTR of a modified pmSAV3 plasmid was exchanged with the structural ORF and 3'UTR through an introduced XbaI site in the junction region. (B) IFAT on CHSE cells infected with supernatant from cells transfected with the prSAV3 plasmid. (C) Cytopathic effect in CHSE cells infected with supernatant containing recombinant SAV3 passage 3. (D) Identification of the introduced XbaI genetic tag by sequencing of an RT-PCR product obtained from RNA extracted from infected cell layers (passage 3) showing cytopathic effect.