FIG. 2.

Southern blot analysis of the UL25 null mutant. DNA was extracted from Vero cells infected with KOS (lanes 1), two independent isolates of the KUL25NS mutant (lanes 2 and 3), or a plaque isolate of the KUL25NS mutant that grew on Vero cells (lanes 4). The DNA was digested with BamHI and SpeI, and the resulting restriction fragments were separated on a 0.8% agarose gel and transferred to GeneScreen Plus. The filters were hybridized with a UL25-specific probe (BamHI fragment, nucleotides 48634 to 50791). The 0.5-kb UL25 fragment (lanes 2 and 3) ran off the bottom of the gel.