Tn7-mediated introduction of DNA into bacmid-cloned pseudorabies virus genome for rapid construction of recombinant viruses

lacZα-mini-attTn7 was inserted into the intergenic region between the gG and gD genes in a PRV bacterial artificial chromosome (BAC) by homologous recombination in E. coli. The resulting recombinant BAC (pBeckerZF1) was confirmed by PCR and sequencing. Green fluorescent protein (GFP) gene was then transposed into pBeckerZF1 by transposon Tn7 to generate pBeckerZF2. Recombinant viruses vBeckerZF1 and vBeckerZF2 were generated by transfection with the corresponding BAC pBeckerZF1 or pBeckerZF2. The titers and cytopathic effect (CPE) observed for by vBeckerZF1 and vBeckerZF2 was comparable to that of the parental virus vBecker3. vBeckerZF2 was serial passaged for five rounds in cell culture, and the mini-Tn7 insertion was stably maintained in viral genome. These results show that recombinant viruses can be rapidly and reliably created by Tn7-mediated transposition. This technology should accelerate greatly the pace at which recombinant PRV can be generated and, thus, facilitate the use of recombinant viruses for detailed mutagenic studies.