FIG. 1.
Recombinant HSV-1 constructs. (A) Structure of the UL41-BAC targeting vector. At the top is a schematic representation of the HSV-1 genome and the corresponding Δa cosmid set, comprised of cos6Δa, cos48Δa, cos14, cos28, and cos56. The UL41 gene is located within cos56, as shown enlarged in the middle. Open reading frames are indicated by open arrows. The bottom shows the structure and orientation of the UL41-BAC targeting construct, including the pac cassette containing the HSV-1 pac element and the α fragment of the bacterial lacZ gene. The large crosses indicate the regions of homology between the targeting vector and cos56 that will facilitate homologous recombination to generate a packaging-proficient recombinant virus. The relative location and orientation of the oligonucleotide primers used for PCR are as indicated. Primers 40 and 42 are located outside of the region of homology with the UL41-BAC targeting construct. (B) Structure of the pHSVlac amplicon vector. The HSV-1 oriS and pac elements provide for helper-dependent packaging of the vector. Expression of the bacterial lacZ reporter gene is controlled by the HSV-1 IE4 promoter and SV40 polyadenylation signals, as indicated. The SV40 ori element was cloned into the unique BamHI site adjacent to the HSV pac element.