FIG. 1.

Targeting constructs and the Us11-related proteins that they are designed to express. The 5′ and 3′ regions from the HSV-1 tk gene in the illustrated plasmids target homologous recombination to the genomic viral tk locus and create tk-negative recombinant viruses. Transcription from the HSV-1 α27 promoter occurs at immediate-early times postinfection, and the direction of transcription from this promoter is indicated with an arrow. Transcripts are polyadenylated at the poly(A)⁺ addition site within the 3′ tk region. 11S-UF expresses the full-length, 155-amino-acid Us11 protein from the wild-type Patton strain. The region that encodes the amino-terminal 87 amino acids is shaded, while the region encoding the carboxy-terminal 68 amino acids appears as a checkerboard. Δ88-155 expresses the amino-terminal 87 amino acids, and Δ5-87 fuses the amino-terminal 4 amino acids to the carboxy-terminal 68 residues. Δ5-87fs contains a single nucleotide insertion at codon 3 that results in a +1 frameshift (fs) but is otherwise isogenic to the insert in Δ5-87.