The α protein ICPO does not appear to play a major role in the regulation of herpes simplex virus gene expression during infection in tissue culture

Abstract

The herpes simplex virus type 1 (HSV-1) alpha protein ICP0 trans-activates HSV-1 early genes in transient expression assays. To investigate the function of ICP0 during HSV-1 infection, we have lowered the level of ICP0 by use of a recombinant plasmid that has been engineered to express the antisense message. Cell lines were constructed which stably carry the antisense plasmid. Total protein profiles from infected antisense cell lines showed that the level of ICP0 was reduced to less than 10% of the wild type level in two of the cell lines. However, reducing the level of ICP0 did not have a significant effect on the expression of HSV-1 early or late genes. The polypeptide patterns for the remaining infected cell polypeptides were similar in that no bands were absent although there were some quantitative differences. The level of two early proteins, glycoprotein B and glycoprotein D was reduced in one of the cell lines, however, levels were nearly equivalent to the control infection for two other cell lines tested. Virus yields were the same for the antisense cell lines and for parent cells. Decreased ICP0 levels did not lead to more restrictive phenotypes for an alpha 4 or alpha 27 mutant as protein patterns were similar for these mutants in antisense and parent cells. Therefore, while ICP0 has been demonstrated to be a strong inducer of gene expression in transient expression assays, it does not appear to have a major role as an activator during the productive infection of tissue culture cells.

Herpes simplex virus latency-associated transcript is a stable intron.

“…5B) and cotransfection with a plasmid containing LAT with no promoter has no effect on transactivation of the TK promoter by ICPO. Although antisense inhibition of ICPO gene function has been demonstrated (30) by driving the opposite strand of ICPO, it is shown here that the LAT intron itself can inhibit ICPO function.…”

Inhibition of SV40 replicon function by engineered antisense RNA transcribed by RNA polymerase III.

“…In a number of studies with animal cells, using either stably integrated or transiently expressed 'antisense genes' optimal levels of inhibition of expression of specific proteins has varied from 80 to 90% (Chang andStoltzfus, 1985, Crowley et al, 1985;Izant and Weintraub 1984;Kim and Wold, 1985;McGarry and Lindquist, 1986;Sandri-Goldin et al, 1987). It is difficult to compare our results on antisense RNA-mediated inhibition of DNA replication with these studies involving measurement of suppression of synthesis of a specific protein.…”

A Neuron-Specific Host MicroRNA Targets Herpes Simplex Virus-1 ICP0 Expression and Promotes Latency

“…The ICP0-WT plasmid (pRS-1) was a generous gift of Rozanne Sandri-Goldin (Sandri-Goldin et al, 1987). This plasmid includes the entire ICP0 gene, with its promoter, cloned into pUC-18.…”