The Rana grylio virus (RGV) is a member of the genus Ranavirus. It belongs to the family Iridoviridae, and contains the gene 67R encoding dUTPase. In order to investigate the function of 67R in the replication and infection of RGV, we constructed Δ67R-RGV, a recombinant virus with deletion of 67R. First, we constructed the plasmid pGL3-67RL-p50-EGFP-67RR which carried an enhanced green fluorescence gene (EGFP) as a selectable marker. After homologous recombination between pGL3-67RL-p50-EG- FP-67RR and the RGV genome, Epithelioma papulosum cyprini (EPC) cells were infected with the resulting mixture. Through ten successive rounds of plaque isolation via EGFP selection, all plaques emitted green fluorescence, and finally Δ67R-RGV was generated. Total DNA of Δ67R-RGV infected cells was extracted for PCR analyses. Simulateously, mock infected and wild-type RGV (wt-RGV) infected cells were used as a comparison. Results showed that 67R could be detected in wt-RGV infected cells, but that only the EGFP gene was detected in Δ67R-RGV infected cells. Furthermore, one-step growth curves of wt-RGV and Δ67R-RGV were similar. Therefore, 67R and its encoding product dUTPase might not be essential for the growth of RGV. These results suggest that, homologous recombination and recombinant rana- virus could be used to study the gene function of viruses in aquatic animals.
Genes, Viral ; physiology ; Genome, Viral ; Polymerase Chain Reaction ; Pyrophosphatases ; genetics ; Ranavirus ; genetics ; Recombination, Genetic