Research Note: Duck Plague Virus Glycoprotein I Influences Cell-Cell Spread And Final Envelope Acquisition

To determine the role of glycoprotein I (gI) in duck plague virus (DPV), a gI-deleted mutant (BAC-CHv-Delta gI) and a gI-revertant virus (BAC-CHv-Delta gI Rev) were constructed by using a markerless twostep Red recombination system implemented on the DPV genome cloned into a bacterial artificial chromosome (BAC). Mutants were characterized on duck embryo fibroblast (DEF) cells compared with wildtype virus. BAC-CHv-Delta gI produced viral plaques on DEF cells that were on average approximately 57.2% smaller than those produced by BAC-CHv-Delta gI Rev and wild-type virus. Electron microscopy confirmed that deleting of gI resulted in nucleocapsids accumulated around the cytoplasm vesicles and few of them could complete the final envelopment process. These results clearly indicated that DPV gI plays significant roles in viral cell-cell spread and viral final envelopment process.