Anatomy of herpes simplex virus DNA. VII. αRNA Is homologous to noncontiguous sites in both the L and S components of viral DNA

Previous reports from this laboratory (Honess and Roizman, 1974) have operationally defined α polypeptides as the viral proteins that are synthesized first in HEp-2 cells treated with cycloheximide from the time of infection with herpes simplex virus type 1 until the withdrawal of the drug 12 to 15 hr after infection. It has also been shown that the viral RNA (designated α RNA) that accumulates in the cytoplasm during cycloheximide treatment and on polyribosomes immediately upon withdrawal of the drug is homologous to 10 to 12% of viral DNA, whereas the viral RNA accumulating in the cytoplasm of untreated cells at 8 to 14 hr after infection is homologous to 43% of viral DNA (Kozak and Roizman, 1974). In the present study, α RNA and cytoplasmic RNA extracted from untreated cells 8 hr after infection were each hybridized in liquid to in vitro labeled restriction endonuclease fragments generated by cleavage of herpes simplex virus type 1 DNA with Hsu I, with Bgl II, and with both enzymes simultaneously. The data show that only a subset of the fragments hybridized to α RNA, and these are scattered within both the L and S components of the DNA. There are at least 5 noncontiguous regions in the DNA homologous to α RNA; two of these are located partially within the reiterated sequences in the S component. All fragments tested hybridized more extensively with 8 hr cytoplasmic RNA than with α RNA. Four adjacent fragments, corresponding to 30% of the DNA and mapping within the L component, hybridized exclusively with the cytoplasmic RNA extracted from cells 8 hr after infection.