The immediate-early regulatory protein ICP22 is required for efficient replication of herpes simplex virus type 1 in some cell types (permissive) but not in others (restrictive). ICP35 in B capsids was more resistant to trypsin digestion of intact capsids than pUL6, pUL15, pUL17, pUL28, or pUL33. To further understand the role of ICP34.5 in evasion of the antiviral response, we used transcriptional profiling to examine host cell gene expression in both wild-type and ICP34.5-null virus-infected mouse embryo fibroblasts over a time course of infection. Specifically, mutational analysis of gH aimed at increasing or decreasing the ability of HR-2 to form a coiled coil resulted in an increase or decrease of fusion activity, respectively. Deconvolution microscopy was used to view 200-nm sections of axons. Some, but not all, severely disabled mutants were compromised in the ability to bind VP23 or VP5. Consistent with this finding, expression of cellular S-phase cyclins was altered in an ICP22/US1.5-dependent manner specifically when S-phase Vero cells were infected.
The mutant did not attach to or enter cells more quickly than did wild-type virus. Strikingly, incubation of wild-type virus with 1 to 2 μM ISIS 5652 at 37°C led to a time-dependent, irreversible loss of infectivity (virucidal activity). By contrast, mutants gE-495 (lacking 56 C-terminal residues) and gE-470 (lacking 81 residues) accumulated in the TGN but did not traffic to cell junctions and did not mediate cell-to-cell spread. Herpes simplex virus type 1 (HSV-1) is a large enveloped DNA virus that causes considerable human illness. We hypothesize that the GT-rich oligonucleotide induces a conformational change in gB that results in inactivation of infectivity.