Utilization of vaccinia virus promoters by fowlpox virus recombinants

Abstract

The ability of fowlpox virus (FPV) to recognize vaccinia virus promoters was indicated by the transient expression of ß‐galactosidase (ß‐gal) when a plasmid containing a vaccinia P11 promoter‐bacterial lacZ gene fusion was transfected into FPV‐infected cells. Based on this apparent utilization of a heterologous poxvirus promoter, FPV recombinants capable of expressing ß‐gal were created. For this purpose, plasmids which would direct the insertion of a foreign transcriptional unit into the FPV thymidine kinase (TK) gene were constructed. Following plasmid transfection of FPV‐infected monolayers, the recombinants in the progeny were partially selected due to their TK phenotype and visually identified by screening plaques for the presence of ß‐gal. The predicted location of the foreign DNA in the recombinant FPV genome was verified by restriction enzyme analysis and subsequent hybridization studies. A second recombinant, in which the vaccinia late P11 promoter had been replaced by the early‐late P7.5 promoter, was also created. The transcriptional regulatory natures of both translocated promoters were retained, even though they were less efficient in the heterologous virus.