The murine homolog (Mph) of human herpes simplex virus entry protein B (HveB) mediates entry of pseudorabies virus but not herpes simplex virus types 1 and 2.

A mouse member of the immunoglobulin superfamily, originally designated the murine poliovirus receptor homolog (Mph), was found to be a receptor for the porcine alphaherpes virus pseudorabies virus (PRV). This mouse protein, designated here murine herpes simplex virus entry protein B (mHveB), is most similar to one of three related human alphaherpes virus receptors, the one designated HveB and also known as poliovirus receptor-related protein 2. Hamster cells resistant to PRV entry became susceptible upon expression of a cDNA encoding mHveB. Anti-mHveB antibody and a soluble protein composed of the mHveB ectodomain inhibited mHveB-dependent PRV entry. Expression of mHveB mRNA was detected in a variety of mouse cell lines, but anti-mHveB antibody inhibited PRV infection in only a subset of these cell lines, indicating that mHveB is the principal mediator of PRV entry into some mouse cell types but not others. Coexpression of mHveB with PRV gD, but not herpes simplex virus type 1 (HSV-1) gD, inhibited entry activity, suggesting that PRV gD may interact directly with mHveB as a ligand that can cause interference. By analogy with HSV-1, envelope-associated PRV gD probably also interacts directly with mHveB during viral entry.

On the control of late gene expression in Kaposi's sarcoma-associated herpes simplex virus (human herpes simplex virus-8).

Herpesvirus late genes require viral DNA replication for maximal expression. Although late gene expression appears to require DNA replication in cis in alphaherpes viruses, studies in Epstein-Barr virus (EBV) suggest that this cis-requirement might not pertain to the gammaherpes viruses. Based on these findings, a system was created to investigate the elements required for the regulation of Kaposi's sarcoma-associated herpes simplex virus (KSHV; human herpes simplex virus-8) late gene expression. The transcript of a classic late gene encoding the viral assembly protein was characterized and reporter genes driven by the assembly protein promoter region were constructed. Unlike the EBV case, expression of a reporter gene under the control of the assembly protein promoter did not display authentic regulation when removed from the context of the viral genome. Although reporter expression rose in cells displaying lytic replication, this expression was not diminished by specific inhibitors of viral DNA synthesis. Minimal core promoters were similarly unable to reproduce late gene regulation. These results suggest that proper KSHV late gene expression is likely to be dependent upon virus lytic replication in cis and indicate that the regulation of KSHV late genes more closely resembles that observed in herpes simplex virus than that described for EBV.

A synthetic peptide from a heptad repeat region of herpes simplex virus glycoprotein B inhibits virus replication.

Glycoprotein B (gB) is the most conserved glycoprotein of herpes simplex viruses and plays important roles in virus infectivity. Two intervening heptad repeat (HR) sequences were found in the C-terminal half of all herpes simplex virus gBs analysed. A synthetic peptide derived from the HR region (aa 477-510) of bovine herpes simplex virus type 1 (BoHV-1) gB was studied for its ability to inhibit virus replication. The peptide interfered with cell-to-cell spread and consistently inhibited replication of BoHV-1, with a 50 % effective concentration value (EC(50)) of 5 microM. Inhibition of replication was obtained not only with herpes simplex viruses including pseudorabies virus and herpes simplex virus type 1 but also partly with Newcastle disease virus. Possible mechanisms of membrane fusion inhibition by the peptide are discussed.

Tumor necrosis factor-alpha response and herpes simplex virus infection in Bell's palsy.

OBJECTIVES: To attempt early diagnosis of patients with Bell's palsy by detection of herpesviral DNA in body fluids, and to investigate whether tumor necrosis factor-alpha (TNF-alpha), a cytokine associated with demyelination, is involved in the inflammatory response in this disease. STUDY DESIGN: Eleven patients with acute facial palsy admitted within 1 week after onset of the disease were followed in a consecutive prospective study. METHODS: Antibodies reactive to herpes simplex viruses were determined by enzyme-linked immunosorbent assay in serum samples from acute and convalescent (> 2-week interval) cases. Intrathecal antibody response was investigated by immunoblotting. Polymerase chain reaction amplification of herpesviral DNA was attempted from samples of serum, cerebrospinal fluid, tear fluid, and saliva TNF-alpha and its soluble receptors (types I and II) were assessed in serum and cerebrospinal fluid samples. RESULTS: Ten of the 11 patients demonstrated serologic evidence of herpesviral primary infection or reactivation, supporting the evidence that herpes simplex viruses are the most prevalent etiologic agents in Bell's palsy. Despite this, DNA amplifications by polymerase chain reaction were negative for herpes simplex viruses in the body fluids tested. TNF-alpha concentrations were significantly elevated in serum, as compared with controls. Only one patient had a remaining facial nerve dysfunction at follow-up after 3 months. CONCLUSION: The absence of herpes simplex DNA in body fluids in the acute stage of serologically confirmed Bell's palsy suggests that viral replication is transient in cases with an early restoration of the facial nerve function. The elevated serum levels of TNF-alpha indicate that this cytokine might be a pathogenetic factor related to the demyelination in this disease.

Centripetal transport of herpes simplex virus in human retinal pigment epithelial cells in vitro.

Herpes Simplex virus displays tropism for neurons and other polarized epithelial cells. We have grown human retinal pigment epithelial cells in culture to study potential mechanisms whereby herpes simplex virus (type I) is transported from the plasma membrane of the cell to the nucleus. The cells were highly polarized as determined by a variety of criteria. They were tightly coupled by junctional complexes, as determined by electron microscopy, immunofluorescent staining of tight junctions and measurements of transepithelial electrical resistances > 200 omega cm2. Immunofluorescence and confocal microscopy were used to visualize microtubule orientation. The microtubules were arranged (i) in a single apical cilium, (ii) in a meshwork beneath the apical membrane and (iii) in longitudinally arranged bundles near the lateral membranes and nucleus. The latter microtubules were primarily oriented with their plus ends directed toward the basal surface of the cells. We infected retinal pigment epithelial cells at the apical surface with virus and assayed the uptake and transport of virus to the nucleus by quantitative immunoblot and immunocytochemical staining for the viral immediate early gene product, infected cell protein 4. The antigen first appeared in retinal pigment epithelial cells 2 h after infection. Treatment of the cells with 33 microM nocodazole, a microtubule-destabilizing drug, delayed the appearance of the viral antigen by 1 h. The effect of nocodazole treatment on microtubule integrity was confirmed by immunofluorescent staining and immunoblots of tubulin. Both cytoplasmic dynein and the ubiquitous form of kinesin were identified in the cells using immunoblots. These novel data indicate that human retinal pigment epithelial cells, like neurons, are susceptible to infection by herpes simplex virus and that the centripetal transport of virus to the nucleus in both cell types is facilitated by microtubules. The orientation of microtubules in retinal pigment epithelial cells suggests that the transport of herpes simplex virus from the apical surface is mediated by a microtubule-activated motor enzyme, possibly kinesin.

Detection and species-level identification of primate herpes simplex viruses with a comprehensive PCR test for human herpes simplex viruses.

A comprehensive assay for the identification of all eight human herpes simplex viruses has been previously reported. This assay was extended to the detection and species-level identification of herpes simplex B virus (Cercopithecine herpes simplex virus 1) and African green monkey cytomegalovirus (Cercopithecine herpes simplex virus 5), two herpes simplex viruses of relevance to the clinical virology laboratory.

Agents and strategies in development for improved management of herpes simplex virus infection and disease.

The quiet pandemic of herpes simplex virus (HSV) infections has plagued humanity since ancient times, causing mucocutaneous infection such as Herpes Labialis and herpes simplex genitalis. Disease symptoms often interfere with every-day activities and occasionally HSV infections are the cause of life-threatening or sight-impairing disease, especially in neonates and the immuno-compromised patient population. After infection the virus persists for life in neurons of the host in a latent form, periodically reactivating and often resulting in significant psychosocial distress for the patient. Currently no cure is available. So far, vaccines, ILs, IFNs, therapeutic proteins, antibodies, immunomodulators and small-molecule drugs with specific or non-specific modes of action lacked either efficacy or the required safety profile to replace the nucleosidic drugs Acyclovir, Valacyclovir ( Valtrex ), Penciclovir ( Denavir ) and Famciclovir ( Famvir ) as the first choice of treatment. The recently discovered inhibitors of the HSV helicase-primase are the most potent development candidates today. These antiviral agents act by a novel mechanism of action and display low resistance rates in vitro and superior efficacy in animal models. This review summarises the current therapeutic options, discusses the potential of preclinical or investigational drugs and provides an up-to-date interpretation of the challenge to establish novel treatments for herpes simplex disease.

Famiciclovir therapy (famvir) for herpes simplex and herpes zoster infections.

Genital herpes simplex and herpes zoster infections are common afflictions that are associated with significant morbidity and a decreased quality of life. Famciclovir ( Famvir ) (Famvir, Novartis) is an orally administered prodrug of the antiviral agent Penciclovir ( Denavir ). Its unique pharmacokinetic profile makes it an efficacious, convenient and well-tolerated alternative to the traditionally prescribed Acyclovir. Famciclovir ( Famvir ) is used for the acute treatment and suppressive therapy of recurrent genital herpes simplex as well as for herpes zoster and its debilitating comorbidities. Famiciclovir allows patients to manage or prevent symptoms, thereby significantly improving their quality of life. Its favorable safety profile makes it a good treatment choice for the elderly as well as for immunocompromised patients, including those infected with HIV.

Nectin2alpha (PRR2alpha or HveB) and nectin2delta are low-efficiency mediators for entry of herpes simplex virus mutants carrying the Leu25Pro substitution in glycoprotein D.

The receptors for entry of herpes simplex viruses 1 and 2 (HSV-1 and -2), widely expressed in human cell lines, are members of a subset of the immunoglobulin superfamily exemplified by herpes simplex virus entry mediator C (HveC) and the herpes simplex virus immunoglobulin-like receptor (HIgR). This report focuses on two members of this subset, herpes simplex virus entry mediator B (HveB), recently designated nectin2/PRR2alpha, and its splice variant isoform, nectin2/PRR2delta. Nectin2alpha and -delta share the ectodomain but differ in the transmembrane and cytoplasmic regions. HveB was reported to enable entry of HSV-1 carrying mutations in glycoprotein D (gD) and of HSV-2, but not of wild-type (wt) HSV-1. We report that (i) both nectin2alpha and -delta served as receptors for the entry of HSV-1 mutant viruses HSV-1(U10) and -(U21) and AP7(r) that carry the Leu25Pro substitution in gD but not for HSV-1 mutants U30 and R5000 that carry the Ser140 or Ala185 substitution in gD. All of these mutants were able to overcome the block to entry mediated by expression of wt gD. (ii) Infection of cells expressing nectin2alpha or -delta required exposure to multiplicities of infection about 100-fold higher than those required to infect cells expressing HveC or HIgR. (iii) gD from HSV-1(U21) bound in vitro soluble forms of nectin2. The association was weaker than that to the soluble form of HveC/HIgR. Binding of wt HSV-1 gD to soluble nectin2 was not detectable. (iv) A major region of nectin2 functional in virus entry mapped to the V domain, located at the N terminus.

Interaction of HSV-1 infected peripheral blood mononuclear cells with cultured dermal microvascular endothelial cells: a potential model for the pathogenesis of HSV-1 induced erythema multiforme.

The effect of herpes simplex virus infection on human dermal microvascular endothelial cells and herpes-virus-1-infected peripheral blood mononuclear cells on human dermal microvascular endothelial cells was studied as a model of herpes-associated erythema multiforme. After infection of human dermal microvascular endothelial cells with native herpes simplex virus and overnight culture, 60%--90% of human dermal microvascular endothelial cells showed cytopathic effects. HLA class I molecules and CD31 (PECAM-1) surface expression in herpes-virus-infected endothelial cells were substantially downregulated, whereas CD54 (ICAM-1) remained unchanged. Cocultivation with herpes-virus-1-infected peripheral blood mononuclear cells left characteristic plaques on the human dermal microvascular endothelial cell monolayer; however, very few human dermal microvascular endothelial cells (1%--3%) were infected. Adhesion molecule expression of human dermal microvascular endothelial cells cocultivated with herpes-virus-infected peripheral blood mononuclear cells demonstrated a 5-fold increase in CD54 expression, a 2-fold increase in HLA class I expression, but no change of CD31 by fluorescence-activated cell sorter analysis. Incubation of human dermal microvascular endothelial cells with ultraviolet-C irradiated herpes-virus-infected peripheral blood mononuclear cells had no effect on morphology or adhesion molecule expression levels. Changes of adhesion molecule expression by direct infection or cocultivation with peripheral blood mononuclear cells (with native and ultraviolet-C inactivated herpes simplex virus infection) were also documented at the mRNA level. Adhesion assays demonstrated an increased binding of herpes-virus-infected peripheral blood mononuclear cells versus noninfected peripheral blood mononuclear cells to noninfected human dermal microvascular endothelial cells. Our results suggest that incubation of herpes-virus-infected peripheral blood mononuclear cells with human dermal microvascular endothelial cells induces significant upregulation of CD54 and major histocompatibility complex class I molecules in the surrounding noninfected human dermal microvascular endothelial cells, which is associated with an increased binding of peripheral blood mononuclear cells. Our in vitro findings may serve as a model for herpes-associated erythema multiforme possibly explaining the dermal inflammatory reaction seen in that condition.