Herpes simplex virus-mediated activation of human immunodeficiency virus is inhibited by oligonucleoside methylphosphonates that target immediate-early mRNAs 1 and 3

3-Hydroxyphthaloyl β-Lactoglobulin. IV. Antiviral Activity in the Mouse Model of Genital Herpesvirus Infection

The spread of sexually transmitted infections caused by herpes simplex virus type 2 (HSV-2) has continued unabated despite educational efforts generated in response to the human immunodeficiency virus (HIV) epidemic. Given the absence of effective vaccines, this indicates the need to develop prophylactic measures such as topical antiviral agents. Chemical modification of bovine β-lactoglobulin (β-LG), the major protein of whey, by hydroxyphthalic anhydride (3HP) led to the generation of a potent HIV-1 inhibitor designated 3HP-β-LG. This agent was shown to also have antiviral activity against HSV-2 and HSV-1 in vitro. Recent studies indicate that 3HP-β-LG binds to HSV-1 virions, which, at least in part, involves the viral glycoprotein gE. Here we show that 3HP-β-LG inhibits HSV-2 infection in the mouse model of genital HSV-2 infection. Simultaneous exposure to HSV-2 and 3HP-β-LG caused a significant decrease in the proportion of infected animals (27% virus shedding, 5% lesion development and 0% fatality for 3HP-β-LG as compared to 80% shedding, 60% lesion development and 53% fatality in micetreated with PBS). The proportion of animals with HSV-2 infection after treatment with β-LG was similar to that in the PBS-treated group. Pretreatment with 3HP-β-LG formulated in a gel, which prolongs the presence of the agent in the vagina, also significantly reduced the proportion of HSV-2-infected mice (5% virus shedding, 5% lesion development and 0% fatality for 3HP-β-LG as compared to 70% shedding, 60% lesion development and 40% fatality in vehicle-treated mice). These differences were significant ( P≤0.0005, 0.002 and 0.008 for shedding, lesion development and fatality, respectively). Virus titres in the minority of mice that developed infection were similar to those in untreated mice. HSV-2 infection was not inhibited by treatment of an ongoing infection, indicating that 3HP-β-LG interferes with the initial infection. These data suggest that 3HP-β-LG may be an efficacious agent for preventing vaginal transmission of genital herpesvirus infections.

Inhibition of herpes simplex virus 1 gene expression by designer zinc-finger transcription factors

The herpes simplex virus 1 (HSV-1) replicative cycle begins by binding of the viral activator, VP16, to a set of sequences in the immediate-early (IE) gene promoters. With the aim of inhibiting this cycle, we have constructed a number of synthetic zinc-finger DNA-binding peptides by using recently reported methods. Peptides containing either three or six fingers, targeted to a viral promoter, were engineered as fusions with a KOX-1 transcription repression domain. These proteins bound to the HSV-1 IE175k (ICP4) promoter, in vitro, with nanomolar or subnanomolar binding affinity. However, in a chloramphenicol acetyltransferase reporter system, only the six-finger protein was found to repress VP16-activated transcription significantly. Thus the longer array of zinc fingers is required to compete successfully against VP16, one of the most powerful natural activators known. We found that the HSV-1 replication cycle can be partially repressed by the six-finger peptide with the viral titer reduced by 90%.

A novel gene expressed in human keratinocytes with long-term in vitro growth potential is required for cell growth

The herpes simplex virus large subunit of ribonucleotide reductase differs from its counterparts in eukaryotic and prokaryotic cells and in other viruses in that it contains a unique domain that codes for a distinct serine-threonine protein kinase that activates the Ras/MEK/MAPK mitogenic pathway and is required for virus growth. Previous studies suggested that ribonucleotide reductase protein kinase was co-opted from a cellular gene. Cellular genes similar to ribonucleotide reductase protein kinase were not cloned, however, and their function is unknown. Here we report that a novel gene (H11) that codes for a protein similar to herpes simplex virus 2 ribonucleotide reductase protein kinase, is expressed in skin tissues, cultured keratinocytes, and the keratinocyte cell line A431. The protein is phosphorylated and it associates with the plasma membrane. H11 is expressed in keratinocytes with long-term in vitro growth potential and is coexpressed with high levels of adhesion molecules involved in signal transduction, such as beta1 integrin. Antisense oligonucleotides that inhibit H11 expression inhibit DNA synthesis and keratinocyte proliferation, suggesting that H11 expression is required for cell growth.

A novel human gene similar to the protein kinase (PK) coding domain of the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) codes for a serine-threonine PK and is expressed in melanoma cells

The large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) is a multifunctional protein that contains a serine-threonine protein kinase (PK) activity (Nelson, J. W., Zhu, J. , Smith, C. C., Kulka, M., and Aurelian, L. (1996) J. Biol. Chem. 271, 17021-17027). Phylogenetic analyses indicated that ICP10 PK belongs to a distinct subfamily of growth factor receptor serine-threonine PKs that are characterized by their ability to function with a limited number of conserved catalytic motifs (Hunter, J. C. R., Smith, C. C., and Aurelian, L. (1995) Int. J. Onc. 7, 515-522). Here, we report the isolation and characterization of a novel gene, designated H11, that contains an open reading frame of 588 nucleotides, which encodes a protein similar to ICP10 PK. The H11 protein has Mn(2+)-dependent serine-threonine-specific PK activity as determined with a GST-H11 fusion protein and by immununocomplex PK/immunoblotting assays of 293 cells transfected with a H11 eukaryotic expression vector. PK activity is ablated by mutation of Lys(113) within the presumtive catalytic motif II (invariant Lys). 293 cells stably transfected with H11 acquire anchorage-independent growth. Endogenous H11 RNA and the H11 phosphoprotein are expressed in melanoma cell lines and primary melanoma tissues at levels higher than in normal melanocytes and in benign nevi. Melanoma cell proliferation is inhibited by treatment with antisense oligonucleotides that inhibit H11 translation, suggesting that H11 expression is associated with cell growth.

Herpes simplex virus type 2 growth and latency reactivation by cocultivation are inhibited with antisense oligonucleotides complementary to the translation initiation site of the large subunit of ribonucleotide reductase (RR1)

Antisense oligonucleotides complementary to the translation initiation site of the herpes simplex virus type 2 (HSV-2) large subunit of ribonucleotide reductase (RR1) were studied for their ability to inhibit RR1 expression, HSV-2 growth, and its reactivation from latently infected ganglia. The oligomers caused a significant decrease (90%-97% inhibition) in HSV-2 RR1 expression and inhibited HSV-2 growth, with IC50 and IC90 values of 0.11 and 1.0 microM, respectively. The titers of HSV-2 mutants that are respectively deleted in the PK (ICP10deltaPK) or RR (ICP10deltaRR) domains of RR1 were also significantly (500-20,000-fold) decreased, indicating that the antisense oligomers interfere with the independent contributions of the two RR1 functions (PK and RR) toward virus growth. Inhibition was sequence specific, as evidenced by the failure of a two-base mutant (RR1TImu) to inhibit protein expression and HSV-2 growth. Furthermore, the antisense oligomers inhibited HSV-2 reactivation by cocultivation of latently infected ganglia (0/8). Virus was reactivated from ganglia cultured without oligomers, in the presence of unrelated oligomers (6/8), or in the presence of the two-base mutant RR1TImu (5/8) (p < 0.007 by two-tailed Fisher exact test). HSV-2 growth was not inhibited by antisense oligonucleotides complementary to the splice junction of HSV-2 immediate-early (IE) pre-mRNA 4 and 5 (IE4,5SA) or the translation initiation site of IE mRNA 4 (IE4TI), although the respective HSV-1-specific oligomers inhibit HSV-1 growth.

Cellulose acetate phthalate (CAP): an 'inactive' pharmaceutical excipient with antiviral activity in the mouse model of genital herpesvirus infection

The spread of sexually transmitted infections caused by herpes simplex virus type 2 (HSV-2) has continued unabated. At least 20% of the United States population has been infected with HSV-2 and there is a high probability of further virus transmission by asymptomatic carriers. Given the absence of effective vaccines, this indicates the need to develop prophylactic measures such as topical microbicides that have antiviral activity. Recent studies indicate that cellulose acetate phthalate (CAP), an inactive pharmaceutical excipient commonly used in the production of enteric tablets and capsules, is a broad specificity microbicide against diverse sexually transmitted pathogens. When appropriately formulated in micronized form, it inactivates various viruses, including HSV-2, in vitro. Here we show that CAP inhibits HSV-2 infection in the mouse model of genital HSV-2 infection. Pretreatment with micronized CAP formulated in a glycerol-based cream with colloidal silicone dioxide significantly reduced the proportion of HSV-2-infected mice (10% virus shedding, 0-5% lesion development and 0% fatality for CAP as compared to 84% shedding, 63% lesion development and 63% fatality in saline-treated mice). These differences were significant (P < or = 0.0002 by the test of equality of two proportions). Virus titres in the minority of mice that developed infection were similar to those in untreated mice. HSV-2 infection was not inhibited by treatment with CAP formulated with other inactive ingredients (for example povidone plus crosprovidone) instead of silicone dioxide, presumably reflecting CAP complexation/inactivation. These data suggest that properly formulated, CAP may be an efficacious agent for preventing vaginal transmission of genital herpesvirus infections.

The PK domain of the large subunit of herpes simplex virus type 2 ribonucleotide reductase (ICP10) is required for immediate-early gene expression and virus growth

The large subunit of herpes simplex virus (HSV) ribonucleotide reductase (RR), RR1, contains a unique amino-terminal domain which has serine/threonine protein kinase (PK) activity. To examine the role of the PK activity in virus replication, we studied an HSV type 2 (HSV-2) mutant with a deletion in the RR1 PK domain (ICP10DeltaPK). ICP10DeltaPK expressed a 95-kDa RR1 protein (p95) which was PK negative but retained the ability to complex with the small RR subunit, RR2. Its RR activity was similar to that of HSV-2. In dividing cells, onset of virus growth was delayed, with replication initiating at 10 to 15 h postinfection, depending on the multiplicity of infection. In addition to the delayed growth onset, virus replication was significantly impaired (1,000-fold lower titers) in nondividing cells, and plaque-forming ability was severely compromised. The RR1 protein expressed by a revertant virus [HSV-2(R)] was structurally and functionally similar to the wild-type protein, and the virus had wild-type growth and plaque-forming properties. The growth of the ICP10DeltaPK virus and its plaque-forming potential were restored to wild-type levels in cells that constitutively express ICP10. Immediate-early (IE) genes for ICP4, ICP27, and ICP22 were not expressed in Vero cells infected with ICP10DeltaPK early in infection or in the presence of cycloheximide, and the levels of ICP0 and p95 were significantly (three- to sevenfold) lower than those in HSV-2- or HSV-2(R)-infected cells. IE gene expression was similar to that of the wild-type virus in cells that constitutively express ICP10. The data indicate that ICP10 PK is required for early expression of the viral regulatory IE genes and, consequently, for timely initiation of the protein cascade and HSV-2 growth in cultured cells.