Construction of a reverse genetic system for porcine astrovirus.

In order to construct a full-length infectious cDNA clone of porcine astrovirus, three fragments covering the complete genome of PAstV1-GX1 strain were amplified by RT-PCR. All three PCR-amplified fragments were cloned into T-Vector pMD19 (Simple), and subsequently assembled into a full-length cDNA clone by subcloning. A silent nucleotide change creating a PstI site was engineered into the full-length cDNA clone to distinguish the rescued virus from the parental virus. Upon transfection of BHK-21 cells with the in vitro transcripts of both the original and constructed cDNAs, typical cytopathic effects were observed on PK-15 cells after serial passaging of the cell supernatant. The construction and recovery of the infectious cDNA clone of porcine astrovirus will provide a valuable experimental system to study the genome function and pathogenesis of astroviruses.