FIG. 4.
Southern blot analysis of viral DNA from cells infected with wild-type and mutant viruses. (A) The HSV-1 genome consists of two unique regions, UL and US, which are flanked by repeated sequences a, b, and c. The subscript n in “an” indicates multiple copies of the a sequence. The BamHI fragments corresponding to S, Q, and SQ junction fragments are indicated. (B) Vero cells (107) were infected with the indicated virus at an MOI of 10 PFU/cell for 18 h. Total DNA was digested with BamHI, subjected to electrophoresis, and transferred to a GeneScreen Plus membrane. The membrane was probed with a 32P-labeled BamHI SQ junction fragment. Arrows indicate the junction fragments SQ, Q, and S (from top to bottom). DNA from cells infected with wild-type and null mutant virus (hr81-1) are shown in lanes 1 and 7, respectively. Lanes 2 to 6 contained DNA from cells infected with mutants L120N, Q205E, Q251E, G263A, and Y285S, respectively. Although mutants L120N, Q205E, and hr81-1 appear to contain a reduced amount of SQ DNA compared to wild type and the other mutants, this difference was not reproducible, and we do not feel that it reflects a true reduction in levels of viral DNA synthesis.