Construction of recombinant viruses. The genome of HSV-1, including the US5 (gJ), US6 (gD), US7 (gI), US8 (gE), and US9 genes, is depicted in the upper part of the figure (33). F-US6kan/gE-GFP was derived from F-US6kan (which contains a kanamycin gene cassette inserted between the gD promoter and coding sequences) by replacing gE coding sequences with GFP sequences between two SmaI restriction sites. vRR1097/gEβ was derived from vRR1097 (in which GFP sequences replace gD coding sequences) by replacing gE coding sequences with β-galactosidase sequences. vRR1097/gEβ-R was derived from vRR1097/gEβ by restoring both gD and gE sequences. F-gDβ/gE-GFP was derived from F-gDβ (a mutant in which β-galactosidase sequences replace gD and gI coding sequences) by additionally replacing gE coding sequences with GFP sequences. H represents a HindIII restriction site, S represents SmaI sites, B represents BalI, and N represents an NcoI restriction site.