Current and potential therapies for the treatment of herpes-virus infections

Inhibition of the hERG potassium ion channel by different non-nucleoside human cytomegalovirus polymerase antiviral inhibitor series and the exploration of variations on a pyrroloquinoline core to reduce cardiotoxicity potential

Many non-nucleoside human cytomegalovirus (HCMV) inhibitors have been reported in patent and scientific literature, however, none have reached commercialization despite the urgent need for new HCMV treatments. Herein we report select compounds from different templates that all had low micromolar human ether-à-go-go (hERG) ion channel IC₅₀ values. We also describe a series of pyrroloquinoline derivatives that were designed and synthesized to understand the effect of various substitution on human cytomegalovirus (HCMV) polymerase activity, antiviral activity, and hERG inhibition. These results demonstrated that hERG inhibition can be significantly altered based on the substitution on this template. An HCMV inhibitor with low hERG inhibition and reduced cytotoxicity is also described. The results suggest substitution can be fine tuned for the non-nucleoside polymerase inhibitors to reduce hERG inhibition and maintain HCMV antiviral potency.

Evaluation of Histone Demethylase Inhibitor ML324 and Acyclovir against Cyprinid herpesvirus 3 Infection

Cyprinid herpesvirus 3 (CyHV-3) can cause severe disease in koi and common carp (Cyprinus carpio). Currently, no effective treatment is available against CyHV-3 infection in koi. Both LSD1 and JMJD2 are histone demethylases (HD) and are critical for immediate-early (IE) gene activation essential for lytic herpesvirus replication. OG-L002 and ML324 are newly discovered specific inhibitors of LSD1 and JMJD2, respectively. Here, HD inhibitors were compared with acyclovir (ACV) against CyHV-3 infection in vitro and in vivo. ML324, at 20-50 µM, can completely block ~1 × 103 PFU CyHV-3 replication in vitro, while OG-L002 at 20 µM and 50 µM can produce 96% and 98% inhibition, respectively. Only about 94% inhibition of ~1 × 103 PFU CyHV-3 replication was observed in cells treated with ACV at 50 µM. As expected, CyHV-3 IE gene transcription of ORF139 and ORF155 was blocked within 72 h post-infection (hpi) in the presence of 20 µM ML324. No detectable cytotoxicity was observed in KF-1 or CCB cells treated for 24 h with 1 to 50 µM ML324. A significant reduction of CyHV-3 replication was observed in ~6-month-old infected koi treated with 20 µM ML324 in an immersion bath for 3-4 h at 1-, 3-, and 5-days post-infection compared to the control and ACV treatments. Under heat stress, 50-70% of 3-4-month-old koi survived CyHV-3 infection when they were treated daily with 20 µM ML324 in an immersion bath for 3-4 h within the first 5 d post-infection (dpi), compared to 11-19% and 22-27% of koi in the control and ACV treatments, respectively. Our study demonstrates that ML324 has the potential to be used against CyHV-3 infection in koi.

Quinoxaline Derivatives as Antiviral Agents: A Systematic Review

Background: In recent decades, several viruses have jumped from animals to humans, triggering sizable outbreaks. The current unprecedent outbreak SARS-COV-2 is prompting a search for new cost-effective therapies to combat this deadly pathogen. Suitably functionalized polysubstituted quinoxalines show very interesting biological properties (antiviral, anticancer, and antileishmanial), ensuring them a bright future in medicinal chemistry. Objectives: Focusing on the promising development of new quinoxaline derivatives as antiviral drugs, this review forms part of our program on the anti-infectious activity of quinoxaline derivatives. Methods: Study compiles and discusses recently published studies concerning the therapeutic potential of the antiviral activity of quinoxaline derivatives, covering the literature between 2010 and 2020. Results: A final total of 20 studies included in this review. Conclusions: This review points to a growing interest in the development of compounds bearing a quinoxaline moiety for antiviral treatment. This promising moiety with different molecular targets warrants further investigation, which may well yield even more encouraging results regarding this scaffold.

Efficacy and safety of an extemporaneous preparation of 2% ganciclovir eye drops in CMV anterior uveitis

Background

To evaluate the efficacy and safety of an extemporaneous preparation of 2% ganciclovir topical eye drops in cytomegalovirus (CMV) anterior uveitis because many studies have confirmed the benefits of topical ganciclovir in varying concentrations.

Design

The study employed a retrospective cohort design.

Methods

This study enrolled 11 eyes (11 patients) with CMV anterior uveitis. All cases were proved by positive PCR for CMV DNA from aqueous tapping and received topical 2% ganciclovir, applied every 2 hours daily as induction therapy then tapered off and stopped based on clinical response. Outcome measures were best-corrected visual acuity, anterior chamber cell, coin-shaped and other keratic precipitates, intraocular pressure (IOP), the number of antiglaucoma drugs used, the frequency of steroid eye drops used daily and side effects over a 12-month follow-up period. Side effects after applying topical 2% ganciclovir were recorded using questionnaires and eye examination.

Results

Mean age was 49.0±17.8 years. IOP, number of antiglaucoma drugs used and keratic precipitates decreased significantly at first week (p<0.013, p<0.024 and p<0.031, respectively) followed by decreased anterior chamber cells and significantly reduced frequency of applying steroid eye drops at 4 weeks (p<0.034 and p<0.017, respectively). Visual acuity significantly improved at 5 months continuously. All clinical improvement was maintained to 12 months, and keratic precipitates were eliminated in 90% of all cases. However, in 27% of discontinued medicine cases, inflammation was recurrent. No significance was observed in all factors between recurrent and non-recurrent groups. The most common side effect was eye irritation (27.27%). No severe complications from the medicine was detected.

Conclusion

Extemporaneous preparation topical 2% ganciclovir was effective and safely controlled CMV anterior uveitis. The medication is non-invasive, economical and convenient for hospitals where commercial topical ganciclovir is unavailable.

Novel 1-[5-(4-bromophenoxy)pentyl]-3-(2-arylamino- 2-oxoethyl)uracils and their antiviral properties

The title compounds were prepared from 1-[5-(4-bromophenoxy) pentyl]uracil by the introduction of N-arylacetamide moiety at the 3-position, the better approach involving the use of N-aryl-2-chloroacetamides as the reactants. Antiviral activity of the obtained compounds was estimated.

Anti-Herpes Simplex Virus Type-1 Activity and Phenolic Content of Crude Ethanol Extract and Four Corresponding Fractions of Quercus brantii L Acorn

This research was aimed to evaluate anti–herpes simplex virus type-1 (anti-HSV-1) activity of crude ethanol extract and 4 corresponding fractions of Quercus brantii acorn in vitro. Crude ethanol extract was prepared and subjected to fractionation with different polarity. Anti-HSV-1 activity was evaluated on baby hamster kidney cell line using MTT assay. The inhibitory effect of the plant materials on adsorption and/or post-adsorption stages of HSV-1 replication cycle were determined. Regression analysis was used to determine 50% inhibitory concentration and 50% cytotoxicity concentration, from which selective index was calculated. Based on our results, the chloroform fraction and the crude extract had the highest effect against HSV-1 with selectivity indices of 53.8 and 48.4, respectively. The n-hexane, n-butanol, and chloroform fractions inhibited HSV-1 replication in postadsorption stage (P < .001). The results obtained indicated that the chloroform fraction of Q brantii acorn with high inhibitory effect against HSV-1 replication could be a new promising anti-HSV-1 agent.

Radiogenic Therapy: Novel Approaches for Enhancing Tumor Radiosensitivity

Radiotherapy (RT) is a well established modality for treating many forms of cancer. However, despite many improvements in treatment planning and delivery, the total radiation dose is often too low for tumor cure, because of the risk of normal tissue damage. Gene therapy provides a new adjunctive strategy to enhance the effectiveness of RT, offering the potential for preferential killing of cancer cells and sparing of normal tissues. This specificity can be achieved at several levels including restricted vector delivery, transcriptional targeting and specificity of the transgene product. This review will focus on those gene therapy strategies that are currently being evaluated in combination with RT, including the use of radiation sensitive promoters to control the timing and location of gene expression specifically within tumors. Therapeutic transgenes chosen for their radiosensitizing properties will also be reviewed, these include:

gene correction therapy, in which normal copies of genes responsible for radiation-induced apoptosis are transfected to compensate for the deletions or mutated variants in tumor cells (p53 is the most widely studied example). enzymes that synergize the radiation effect, by generation of a toxic species from endogenous precursors ( e.g., inducible nitric oxide synthase) or by activation of non toxic prodrugs to toxic species ( e.g., herpes simplex virus thymidine kinase/ganciclovir) within the target tissue. conditionally replicating oncolytic adenoviruses that synergize the radiation effect. membrane transport proteins ( e.g., sodium iodide symporter) to facilitate uptake of cytotoxic radionuclides.

The evidence indicates that many of these approaches are successful for augmenting radiation induced tumor cell killing with clinical trials currently underway.

Unexpected features and mechanism of heterodimer formation of a herpesvirus nuclear egress complex

Herpesvirus nucleocapsids escape from the nucleus in a process orchestrated by a highly conserved, viral nuclear egress complex. In human cytomegalovirus, the complex consists of two proteins, UL50 and UL53. We solved structures of versions of UL53 and the complex by X-ray crystallography. The UL53 structures, determined at 1.93 and 3.0 Å resolution, contained unexpected features including a Bergerat fold resembling that found in certain nucleotide-binding proteins, and a Cys3His zinc finger. Substitutions of zinc-coordinating residues decreased UL50-UL53 co-localization in transfected cells, and, when incorporated into the HCMV genome, ablated viral replication. The structure of the complex, determined at 2.47 Å resolution, revealed a mechanism of heterodimerization in which UL50 clamps onto helices of UL53 like a vise. Substitutions of particular residues on the interaction interface disrupted UL50-UL53 co-localization in transfected cells and abolished virus production. The structures and the identification of contacts can be harnessed toward the rational design of novel and highly specific antiviral drugs and will aid in the detailed understanding of nuclear egress.

The extract of Elaeocarpus sylvestris inhibits human cytomegalovirus immediate early gene expression and replication in vitro

Human cytomegalovirus (HCMV) is a major cause of morbidity and mortality in newborn infants, immunocompromised individuals with HIV/AIDS and organ transplant recipients. In order to identify a novel antiviral candidate for HCMV-related diseases, crude ethanol extracts from plants were screened for their potential inhibitory activity on HCMV replication in vitro. Ethanol (70%) extract of Elaeocarpus sylvestris leaves (ESE) markedly inhibited the replication of the HCMV Towne strain without exhibiting any significant adverse effects on the viability of human foreskin fibroblasts (HFF). In addition, ESE significantly downregulated HCMV immediate early (IE) gene expression. Taken together, this is the first study, to the best of our knowledge, demonstrating that ESE has a potent antiviral activity against HCMV by downregulating HCMV IE gene expression and replication.

Design, synthesis, and evaluation of WC5 analogues as inhibitors of human cytomegalovirus Immediate-Early 2 protein, a promising target for anti-HCMV treatment

Although human cytomegalovirus (HCMV) infection is mostly asymptomatic for immunocompetent individuals, it remains a serious threat for those who are immunocompromised, in whom it is associated with various clinical manifestations. The therapeutic utility of the few available anti-HCMV drugs is limited by several drawbacks, including cross-resistance due to their common mechanism of action, i.e., inhibition of viral DNA polymerase. Therefore, compounds that target other essential viral events could overcome this problem. One example of this is the 6-aminoquinolone WC5, which acts by directly blocking the transactivation of essential viral Early genes by the Immediate-Early 2 (IE2) protein. In this study, the quinolone scaffold of the lead compound WC5 was investigated in depth, defining more suitable substituents for each of the scaffold positions explored and identifying novel, potent and nontoxic compounds. Some compounds showed potent anti-HCMV activity by interfering with IE2-dependent viral E gene expression. Among them, naphthyridone 1 was also endowed with potent anti-HIV activity in latently infected cells. Their antiviral profile along with their innovative mechanism of action make these anti-HCMV quinolones a very promising class of compounds to be exploited for more effective antiviral therapeutic treatment.

Antiviral activity of Quercus persica L.: High efficacy and low toxicity

Background:

Drug-resistant strain of Herpes simplex virus type 1 (HSV-I) has increased the interest in the use of natural substances.

Aims:

This study was aimed to determine minimum inhibitory concentration of hydroalchoholic extract of a traditionally used herbal plant, Quercus persica L., on HSV-1 replication on baby hamster kidney (BHK) cells.

Setting:

The study was conducted in Shahrekord University of Medical Sciences, Iran.

Design:

This was an experimental study.

Materials and Methods:

BHK cells were grown in monolayer culture with Dulbecco's modified Eagle's medium (DMEM) supplemented with 5% fetal calf serum and plated onto 48-well culture plates. Fifty percent cytotoxic concentration (CC50%) of Q. persica L. on BHK cells was determined. Subsequently, 50% inhibitory concentration (IC50%) of the extract on replication of HSV-1 both in interacellular and exteracellular cases was assessed.

Statistical Analysis:

Statistic Probit model was used for statistical analysis. The dose-dependent effect of antiviral activity of the extracts was determined by linear regression.

Results:

Q. persica L. had no cytotoxic effect on this cell line. There was significant relationship between the concentration of the extract and cell death (P<0.01). IC50s of Q. persica L. on HSV-1, before and after attachment to BHK cells were 1.02 and 0.257 μg/mL, respectively. There was significant relationship between the concentration of this extract and inhibition of cytopathic effect (CPE) (P<0.05). Antioxidant capacity of the extract was 67.5%.

Conclusions:

The hydroalchoholic extract of Q. persica L. is potentially an appropriate and promising anti herpetic herbal medicine.

Varicella-zoster virus glycoproteins B and E are major targets of CD4+ and CD8+ T cells reconstituting during zoster after allogeneic transplantation

BACKGROUND

After allogeneic hematopoietic stem-cell transplantation patients are at increased risk for herpes zoster as long as varicella-zoster virus specific T-cell reconstitution is impaired. This study aimed to identify immunodominant varicella-zoster virus antigens that drive recovery of virus-specific T cells after transplantation.

DESIGN AND METHODS

Antigens were purified from a varicella-zoster virus infected cell lysate by high-performance liquid chromatography and were identified by quantitative mass spectrometric analysis. To approximate in vivo immunogenicity for memory T cells, antigen preparations were consistently screened with ex vivo PBMC of varicella-zoster virus immune healthy individuals in sensitive interferon-γ ELISpot assays. Candidate virus antigens identified by the approach were genetically expressed in PBMC using electroporation of in vitro transcribed RNA encoding full-length proteins and were then analyzed for recognition by CD4(+) and CD8(+) memory T cells.

RESULTS

Varicella-zoster virus encoded glycoproteins B and E, and immediate early protein 62 were identified in immunoreactive lysate material. Predominant CD4(+) T-cell reactivity to these proteins was observed in healthy virus carriers. Furthermore, longitudinal screening in allogeneic stem-cell transplantation patients showed strong expansions of memory T cells recognizing glycoproteins B and E after onset of herpes zoster, while immediate early protein 62 reactivity remained moderate. Reactivity to viral glycoproteins boosted by acute zoster was mediated by both CD4(+) and CD8(+) T cells.

CONCLUSIONS

Our data demonstrate that glycoproteins B and E are major targets of varicella-zoster virus specific CD4(+) and CD8(+) T-cell reconstitution occurring during herpes zoster after allogeneic stem-cell transplantation. Varicella-zoster virus glycoproteins B and E might form the basis for novel non-hazardous zoster subunit vaccines suitable for immunocompromised transplant patients.

Pathologic and virologic characterization of neuroinvasion by HSV-2 in a mouse encephalitis model

Herpes simplex virus type 2 (HSV-2), a ubiquitous human pathogen associated with genital infections, is neurotropic. It establishes latent infections in local dorsal root ganglia from which it reactivates causing recurrent lesions and frequent episodes of viral shedding. Herpes simplex virus type 2 can also be transmitted from mother to child during birth, causing major neonatal complications including encephalitis. Animal models of HSV-2 genital infection are well described and used for testing of therapies; little is known about animal models of HSV-2-induced encephalitis. We analyzed the pathologic and immunohistochemical features of the nasal rostrum and brain tissue and correlated them with viral distribution in a mouse model of HSV-2 encephalitis induced by intranasal infection and examined viral replication in the brain tissue using quantitative polymerase chain reaction and traditional plaque assay. Our results suggest that the primary route for HSV-2 neuroinvasion after intranasal infection is via the trigeminal pathway, ultimately leading to infection of the brainstem and meningoencephalitis.

Early inhibitors of human cytomegalovirus: state-of-art and therapeutic perspectives

Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, mainly transplant recipients and AIDS patients, and is the most frequent cause of congenital malformations in newborn children. To date, few drugs are licensed for the treatment of HCMV infections, most of which target the viral DNA polymerase and suffer from many drawbacks, including long-term toxicity, low potency, and poor bioavailability. In addition, the emergence of drug-resistant viral strains is becoming an increasing problem for disease management. Finally, none of the current anti-HCMV drugs have been approved for the treatment of congenital infections. For all these reasons, there is still a strong need for new anti-HCMV drugs with novel mechanisms of action. The first events of the virus replication cycle, including attachment, entry, immediate-early gene expression, and immediate-early functions—in particular that of Immediate-Early 2 protein—represent attractive targets for the development of novel antiviral compounds. Such inhibitors would block not only the expression of viral immediate-early proteins, which play a key role in the pathogenesis of HCMV infection, but also the host immunomodulation and the changes to cell physiology induced by the first events of virus infection. This review describes the current knowledge on the initial phases of HCMV replication, their validation as potential novel antiviral targets, and the development of compounds that block such processes.

Herpes Simplex Virus Pneumonia in Patients with Hematologic Malignancies

Herpes simplex virus (HSV) pneumonia is rare and is usually seen in immunocompromised patients. Patients with hematologic malignancies and hematopoietic stem cell transplant (HSCT) are at risk. Most of the cases of HSV pneumonia are caused by HSV-1; however, cases caused by HSV-2 have also been reported. Mucocutaneous disease often precedes the development of pneumonia, with nonspecific symptoms that include fever, cough, and dyspnea. Worsening oxygenation and failure to wean off mechanical ventilation despite broad-spectrum antimicrobial coverage is also a common presentation. Diagnosis requires a high degree of suspicion and is based on isolation of the virus from respiratory secretions and demonstration of cytopathic effects on histopathology. Acyclovir is the most widely used drug for treatment and prophylaxis. With increasing evidence of resistance to acyclovir and its analogs, newer agents such as foscarnet and cidofovir are being recommended as treatment options. Prophylaxis in patients with seropositive HSV undergoing chemotherapy or in the immediate post-HSCT period has been shown to reduce HSV disease rates and mortality rates. This chapter will focus on incidence and transmission, pathogenesis, risk factors, clinical features, diagnosis, and management of HSV pneumonia in patients with hematologic malignancies and HSCT, as well as outcome and prognosis.

Least-Squares Support Vector Machine Approach to Viral Replication Origin Prediction

Replication of their DNA genomes is a central step in the reproduction of many viruses. Procedures to find replication origins, which are initiation sites of the DNA replication process, are therefore of great importance for controlling the growth and spread of such viruses. Existing computational methods for viral replication origin prediction have mostly been tested within the family of herpesviruses. This paper proposes a new approach by least-squares support vector machines (LS-SVMs) and tests its performance not only on the herpes family but also on a collection of caudoviruses coming from three viral families under the order of caudovirales. The LS-SVM approach provides sensitivities and positive predictive values superior or comparable to those given by the previous methods. When suitably combined with previous methods, the LS-SVM approach further improves the prediction accuracy for the herpesvirus replication origins. Furthermore, by recursive feature elimination, the LS-SVM has also helped find the most significant features of the data sets. The results suggest that the LS-SVMs will be a highly useful addition to the set of computational tools for viral replication origin prediction and illustrate the value of optimization-based computing techniques in biomedical applications.

The 6-aminoquinolone WC5 inhibits human cytomegalovirus replication at an early stage by interfering with the transactivating activity of viral immediate-early 2 protein

WC5 is a 6-aminoquinolone that potently inhibits the replication of human cytomegalovirus (HCMV) but has no activity, or significantly less activity, against other herpesviruses. Here we investigated the nature of its specific anti-HCMV activity. Structure-activity relationship studies on a small series of analogues showed that WC5 possesses the most suitable pattern of substitutions around the quinolone scaffold to give potent and selective anti-HCMV activity. Studies performed to identify the possible target of WC5 indicated that it prevents viral DNA synthesis but does not significantly affect DNA polymerase activity. In yield reduction experiments with different multiplicities of infection, the anti-HCMV activity of WC5 appeared to be highly dependent on the viral inoculum, suggesting that WC5 may act at an initial stage of virus replication. Consistently, time-of-addition and time-of-removal studies demonstrated that WC5 affects a phase of the HCMV replicative cycle that precedes viral DNA synthesis. Experiments to monitor the effects of the compound on virus attachment and entry showed that it does not inhibit either process. Evaluation of viral mRNA and protein expression revealed that WC5 targets an event of the HCMV replicative cycle that follows the transcription and translation of immediate-early genes and precedes those of early and late genes. In cell-based assays to test the effects of WC5 on the transactivating activity of the HCMV immediate-early 2 (IE2) protein, WC5 markedly interfered with IE2-mediated transactivation of viral early promoters. Finally, WC5 combined with ganciclovir in checkerboard experiments exhibited highly synergistic activity. These findings suggest that WC5 deserves further investigation as a candidate anti-HCMV drug with a novel mechanism of action.

Testing the susceptibility of human herpesviruses to antivirals

Herpesviruses cause chronic lifelong infections in humans and may cause life-threatening diseases in immunosuppressed patients. Antiviral drugs targeted to viral DNA polymerase, such as acyclovir, penciclovir, ganciclovir, foscarnet and cidofovir, are currently available and have been proven to be efficient against clinical symptoms of herpesvirus infections. The resistance of herpesviruses to these drugs is associated with specific mutations of viral genes encoding either DNA polymerase or enzymes phosphorylating nucleoside analogs. Resistance is detected and characterized by means of specific susceptibility assays, which can be classified as phenotypic, genetic and functional. These tests are used both to investigate novel antiviral compounds and look for the emergence of resistant viruses in treated patients in case of clinical failure. Although susceptibility assays are often time consuming and present some limitations regarding the interpretation of their results, their use in the monitoring of antiherpetic treatments should be promoted and improved, in parallel to the development of novel efficient drugs.

Biochemical, biophysical, and mutational analyses of subunit interactions of the human cytomegalovirus nuclear egress complex

Nuclear egress, the trafficking of herpesvirus nucleocapsids from the nucleus to the cytoplasm, involves two conserved viral proteins that form a complex at the nuclear envelope, referred to as the nuclear egress complex. In human cytomegalovirus, these two proteins are called UL50 and UL53. To study UL50 and UL53 in molecular detail, these proteins were expressed in bacteria and purified. To obtain highly expressed, pure proteins, it was necessary to truncate both constructs based on sequence conservation and predicted secondary structural elements. Size exclusion chromatography and analytical ultracentrifugation studies indicated that the truncated form of UL50 is a monomer in solution, that the truncated form of UL53 is a homodimer, and that, when mixed, the two proteins form a heterodimer. To identify residues of UL53 crucial for homodimerization and for heterodimerization with UL50, we constructed and expressed mutant forms of UL53 containing alanine substitutions in a predicted helix. Isothermal titration calorimetry was used to measure the binding affinities of the UL53 mutants to UL50. UL53 residues, the replacement of which reduced binding to UL50, form a surface on one face of the predicted helix. Moreover, most of the substitutions that reduce UL53-UL50 interactions also reduced homodimerization. Substitutions that reduced the interaction between UL50 and UL53 in vitro also reduced colocalization of full-length UL50 and UL53 at the nuclear rim in transfected cells. These results demonstrate direct protein-protein interactions between these proteins that are likely to be mediated by a helix, and they have implications for understanding nuclear egress and for drug discovery.

Rhesus cytomegalovirus a nonhuman primate model for the study of human cytomegalovirus

Human cytomegalovirus (HCMV), a member of an ancient family of viruses (Herpesviridae), has acquired the capacity to maintain a lifelong persistent infection within an immunocompetent host. Since both primary and recurrent infections are generally subclinical, host antiviral immune responses are effective at limiting the pathogenic potential of HCMV. However, the fact that HCMV can persist in the presence of those protective immune responses indicates that host immunity is unable to prevent or eliminate long-term reservoirs of virus. The ability of HCMV to persist has important clinical implications, a fact reflected by the spectrum of pathogenic outcomes observed in those without a fully functional immune system. Recurrence of viral replication or transmission of HCMV from an infected individual to those most susceptible to primary infection during immune suppression, deficiency, or immaturity can lead to multiorgan disease and, sometimes, death. The clinical need for a protective HCMV vaccine has been recognized for decades, but due to a conspiracy of factors, there is no approved vaccine despite intensive investigations to develop one. Animal models of HCMV have been used as systems of discovery and translation to understand viral mechanisms of persistence and pathogenesis, and to test concepts and modalities for the generation of immune responses that protect from primary infection and sequelae. This review summarizes studies in a nonhuman primate model of HCMV involving infection of rhesus macaques (Macaca mulatta) with rhesus cytomegalovirus (RhCMV). The RhCMV model serves as an important complement to those in other animals, particularly small animals, and the lessons learned from RhCMV should have direct clinical relevance to HCMV and the design of protective vaccines.

Human cytomegalovirus DNA replication: antiviral targets and drugs

Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, in particular transplant recipients and AIDS patients, and is the most frequent congenital viral infection in humans. There are currently five drugs approved for HCMV treatment: ganciclovir and its prodrug valganciclovir, foscarnet, cidofovir and fomivirsen. These drugs have provided a major advance in HCMV disease management, but they suffer from poor bioavailability, significant toxicity and limited effectiveness, mainly due to the development of drug resistance. Fortunately, there are several novel and potentially very effective new compounds which are under pre-clinical and clinical evaluation and may address these limitations. This review focuses on HCMV proteins that are directly or indirectly involved in viral DNA replication and represent already established or potential novel antiviral targets, and describes both currently available drugs and new compounds against such protein targets.

Novel non-nucleoside human cytomegalovirus inhibitors based upon TSAO nucleoside derivatives: structure-activity relationships

TSAO derivatives are a unique group of potent and highly specific inhibitors of HIV-1 replication. We have recently reported 4''-ureido TSAO derivatives that are devoid of anti-HIV-1 activity, but inhibit human cytomegalovirus with an activity comparable to that of Ganciclovir. We herein report the synthesis and biological evaluation of novel 4''-ureido TSAO derivatives in order to evaluate the structural features required for anti-HCMV activity. Interestingly, these studies revealed that the compounds may inhibit HCMV at the DNA polymerase step via a non-nucleoside mechanism.

Human herpes simplex virus infections: epidemiology, pathogenesis, symptomatology, diagnosis, and management

Eight of the more than 80 known herpesviruses are human pathogens. Human herpes simplex virus (HSV) is a contagious infection with a large reservoir in the general population. It has a potential for significant complications in the immunocompromised host. In addition, psychological distress caused by the negative stigma associated with genital herpes and visible facial lesions in those experiencing frequent outbreaks renders it a challenging clinical dilemma. This article reviews the epidemiology, pathogenesis, and diagnostic features of HSV infections, providing the clinician with an up-to-date understanding of the available management strategies for mucocutaneous HSV-induced disease.

Identification of individual structural fragments of N,N'-(bis-5-nitropyrimidyl)dispirotripiperazine derivatives for cytotoxicity and antiherpetic activity allows the prediction of new highly active compounds

OBJECTIVES

The objectives of this study were (i) to apply computer-based technologies to evaluate the structure of 48 N,N'-(bis-5-nitropyrimidyl)dispirotripiperazines which belong to a new class of highly active antiviral compounds binding to cell surface heparan sulphates, (ii) to understand the chemical- biological interactions governing their activities, and (iii) to design new compounds with strong antiviral activity.

METHODS

The logarithm of 50% cytotoxic concentration (CC(50)) in GMK cells, of 50% inhibitory concentration (IC(50)) against herpes simplex virus type 1, and of selectivity index (SI = CC(50)/IC(50)) was used to develop quantitative structure-activity relationships (QSARs) based on simplex representation of molecular structure. The QSAR model was applied to design new compounds. Two of these compounds were synthesized, physico-chemically characterized and tested for cytotoxicity and antiviral activity.

RESULTS

Statistic characteristics for partial least squares models allow the prediction of CC(50), IC(50) and SI values. The QSAR results demonstrate a high impact of individual structural fragments for antiviral activity. Molecular fragments that promote and interfere with antiviral activity were defined on the basis of the obtained models. Electrostatic factors (38%) and hydrophobicity (34%) were the most important determinants of antiherpetic activity. Using the established method, new potential dispirotripiperazine derivatives were computationally designed. Two of these computationally designed compounds were synthesized. The biological test results confirm the computationally predicted values of these compounds.

CONCLUSIONS

The established QSAR model is suitable for the design of new antiherpetic compounds and prediction of their activity.

Enzymatic activities of human cytomegalovirus maturational protease assemblin and its precursor (pPR, pUL80a) are comparable: [corrected] maximal activity of pPR requires self-interaction through its scaffolding domain

Herpesviruses encode an essential, maturational serine protease whose catalytic domain, assemblin (28 kDa), is released by self-cleavage from a 74-kDa precursor (pPR, pUL80a). Although there is considerable information about the structure and enzymatic characteristics of assemblin, a potential pharmacologic target, comparatively little is known about these features of the precursor. To begin studying pPR, we introduced five point mutations that stabilize it against self-cleavage at its internal (I), cryptic (C), release (R), and maturational (M) sites and at a newly discovered "tail" (T) site. The resulting mutants, called ICRM-pPR and ICRMT-pPR, were expressed in bacteria, denatured in urea, purified by immobilized metal affinity chromatography, and renatured by a two-step dialysis procedure and by a new method of sedimentation into glycerol gradients. The enzymatic activities of the pPR mutants were indistinguishable from that of IC-assemblin prepared in parallel for comparison, as determined by using a fluorogenic peptide cleavage assay, and approximated rates previously reported for purified assemblin. The percentage of active enzyme in the preparations was also comparable, as determined by using a covalent-binding suicide substrate. An unexpected finding was that, in the absence of the kosmotrope Na2SO4, optimal activity of pPR requires interaction through its scaffolding domain. We conclude that although the enzymatic activities of assemblin and its precursor are comparable, there may be differences in how their catalytic sites become fully activated.

Antiviral activity of berberine and related compounds against human cytomegalovirus

Berberine chloride (1) and the structurally related compounds were assessed for the anti-human cytomegalovirus (HCMV) activity using the plaque assay. The anti-HCMV activity (IC(50) 0.68 microM) of 1 was equivalent to that (IC(50) 0.91 microM) of ganciclovir (GCV). The mechanism of action by which 1 inhibits the replication of HCMV is presumed to be different from that of GCV; 1 would interfere with intracellular events after virus penetration into the host cells and before viral DNA synthesis.

Generation of a reporter cell line for detection of infectious varicella-zoster virus and its application to antiviral studies

To simplify the titration of infectious varicella-zoster virus (VZV), we generated a reporter cell line that produced luciferase in a dose-dependent manner upon infection with cell-free VZV. A few VZV-infected cells were detectable by coculturing with the cell line. We demonstrated the usefulness of the cell line for antiviral studies.

Trimethylation of histone H3 lysine 4 by Set1 in the lytic infection of human herpes simplex virus 1

Human herpes simplex virus 1 (HSV-1) is a double-stranded DNA virus that causes facial, ocular, and encephalitic disease in humans. Previous work showed that the genome of HSV-1 is associated with acetylated and methylated histones during lytic infection. However, the physiological role of histone modifications in lytic infection of HSV-1 is unclear. We examined the role of protein methylation in lytic infection of HSV-1 using a protein methylation inhibitor, 5'-deoxy-5'-methylthioadenosine (MTA). We found that MTA strongly reduces the transcription and replication of HSV-1. Moreover, MTA treatment decreases the level of trimethylation of lysine 4 in histone H3 (H3K4me3) on the HSV-1 genome. These results suggest that protein methylation, and in particular, histone methylation, is involved in the lytic infection of HSV-1. To delineate the underlying mechanism, we investigated the role of two H3K4 methyltransferases, Set1 and Set7/9, in the lytic infection of HSV-1. Using small interference RNA, we found that the reduction of Set1, but not Set7/9, reduces the transcription and replication of HSV-1 and specifically decreases H3K4me3 on the virus genome. These results indicate that H3K4me3 mediated by Set1 is required for optimal gene expression and replication of HSV-1 during lytic infection and suggest that this pathway could be a potential point of pharmacological intervention during HSV-1 infection.

Selective anti-cytomegalovirus compounds discovered by screening for inhibitors of subunit interactions of the viral polymerase

Better drugs are needed against human cytomegalovirus (HCMV), a pathogen responsible for severe diseases in immunocompromised hosts and newborn children. We investigated whether selective inhibitors of HCMV replication could be discovered by screening for compounds that disrupt the interaction between the accessory subunit of the viral DNA polymerase, UL44, and the C-terminal 22 residues of the catalytic subunit. From approximately 50,000 small molecules, we identified 5 structurally diverse compounds that not only specifically interfere with this interaction, but also with the physical and functional interaction of UL44 with full-length catalytic subunit. These five compounds also inhibited HCMV replication with sub- to low micromolar potency, and at concentrations up to 500-fold lower than those at which they exhibited cytotoxicity. These compounds represent a promising starting point for the development of anti-HCMV drugs.

Systemic Herpes Simplex Virus Infection Following Cadaveric Renal Transplantation: A Case Report

Herpes simplex virus (HSV) infection usually occurs in immunocompromised or severely debilitated patients. It is not so common in patients with renal transplants. The diagnosis can only be made histologically. It usually occurs during or shortly after treatment of graft rejection with high-dose steroids. We have recently experienced a case of HSV esophagitis and nephropathy in the renal allograft biopsy, which was identified by histology, immunostaining, and electron microscopy. A 43-year-old woman underwent cadaveric renal transplantation with cyclosporine and prednisolone treatment. Twelve months later, she developed renal insufficiency and proteinuria. Allograft renal biopsy showed some evidence of acute rejection. She was treated with 3 successive days of methylprednisolone (1.0 g/d) intravenously and continued tapering of steroids. Three weeks after steroid pulse therapy, she had throat pain, oral cavity ulcer, dysphagia, and febrile sensation. Esophagoscopy revealed multiple confluent ulcers in the whole esophagus, and biopsy showed enlarged epithelial cells with prominent nuclei. Immunohistochemically, the epithelial cells were positive with a monoclonal antibody to HSV type 1. She was started on acyclovir intravenously, which was continued for a week. After a week, her symptoms began to improve and repeat endoscopy showed no residual esophagitis. A renal allograft infection with HSV can persist in heavily immunosuppressed patients with recurrent rejection episodes. HSV mainly affects tubular cells causing necrosis, a major reason for functional deterioration. A biopsy is required for diagnosis.

Herpes simplex virus 1 (HSV-1) for cancer treatment

Cancer remains a serious threat to human health, causing over 500 000 deaths each year in US alone, exceeded only by heart diseases. Many new technologies are being developed to fight cancer, among which are gene therapies and oncolytic virotherapies. Herpes simplex virus type 1 (HSV-1) is a neurotropic DNA virus with many favorable properties both as a delivery vector for cancer therapeutic genes and as a backbone for oncolytic viruses. Herpes simplex virus type 1 is highly infectious, so HSV-1 vectors are efficient vehicles for the delivery of exogenous genetic materials to cells. The inherent cytotoxicity of this virus, if harnessed and made to be selective by genetic manipulations, makes this virus a good candidate for developing viral oncolytic approach. Furthermore, its large genome size, ability to infect cells with a high degree of efficiency, and the presence of an inherent replication controlling mechanism, the thymidine kinase gene, add to its potential capabilities. This review briefly summarizes the biology of HSV-1, examines various strategies that have been used to genetically modify the virus, and discusses preclinical as well as clinical results of the HSV-1-derived vectors in cancer treatment.

Scoring schemes of palindrome clusters for more sensitive prediction of replication origins in herpesviruses

Many empirical studies show that there are unusual clusters of palindromes, closely spaced direct and inverted repeats around the replication origins of herpesviruses. In this paper, we introduce two new scoring schemes to quantify the spatial abundance of palindromes in a genomic sequence. Based on these scoring schemes, a computational method to predict the locations of replication origins is developed. When our predictions are compared with 39 known or annotated replication origins in 19 herpesviruses, close to 80% of the replication origins are located within 2% of the genome length. A list of predicted locations of replication origins in all the known herpesviruses with complete genome sequences is reported.

Good oral absorption prediction on non-nucleoside benzothiadiazine dioxide human cytomegalovirus inhibitors using combined chromatographic and neuronal network techniques

The current drugs available against human cytomegalovirus (HCMV) suffer from a number of shortcomings such as toxic side effect, poor bioavailability and/or risk for emergence of drug-resistance virus strains. Due to these limitations, the development of new drugs against HCMV is of great interest. Taking into account the therapeutic potential of benzothiadiazines dioxides (BTD) derivatives, it is most important to know their oral bioavailability because all the current clinical drugs are poorly absorbed. In this work, the utility of CODES neural networks and biopartitioning micellar chromatography (BMC) in predicting pharmacokinetic properties has been used to estimate the oral absorption of BTD derivatives and their efficacy has been verified. The results indicate higher values for BTD derivatives than the currently licensed anti-viral agents.

Review article: oral ulcers and its relevance to systemic disorders

Oral ulceration is a common problem, and is sometimes a marker of gastroenterological disease. Patients with signs or symptoms of oral ulcers are sometimes referred to gastroenterology clinics, however, in most instances the ulcers does not reflect gastrointestinal disease. Indeed, a spectrum of disorders other than those of the gut can give rise to oral mucosal ulcers ranging from minor local trauma to significant local disease such as malignancy or systemic illness. This present article reviews aspects of the aetiology, diagnosis and management of common ulcerative disorders of the oral mucosa.

Seizure, neuron loss, and mossy fiber sprouting in herpes simplex virus type 1-infected organotypic hippocampal cultures

PURPOSE

Epileptic seizures are frequently seen after viral encephalitis. Herpes simplex virus type 1 (HSV-1) encephalitis is the most common cause of acquired epilepsy in humans. However, little information is available about the neuropathogenesis of HSV-1-associated seizures. We have developed an in vitro HSV-1-infected organotypic hippocampal slice culture to elucidate the underlying mechanisms of HSV-1-associated acute seizure activity.

METHODS

Hippocampal slice cultures were prepared from postnatal day 10 to 12 rat pups. Wild-type HSV-1 strain RE (1 x 10(5) PFU) was applied to cultures at 14 days in vitro. The excitability of CA3 pyramidal cells and hippocampal network properties were measured with electrophysiological recordings. Hematoxylin-eosin (H&E) and Timm stains were used.

RESULTS

HSV-1 infection induces epileptiform activity, neuron loss, and subsequently a dramatic increase of mossy fiber sprouting in the supragranular area. With intracellular recordings, surviving CA3 pyramidal cells exhibited a more depolarizing resting membrane potential concomitant with an increase in membrane input resistance and had a lower threshold to generate synchronized bursts and a decrease in the amplitude of afterhyperpolarization than did controls. When the antiherpes agent acyclovir was applied with a delay of 1 or 24 h after HSV-1 infection, a dramatic inhibition of HSV-1 replication and protection of the neuron loss were observed.

CONCLUSIONS

These results suggest that a direct change in the excitability of the hippocampal CA3 neuronal network and HSV-1-induced neuron loss resulting in subsequent mossy fiber reorganization may play an important role in the generation of epileptiform activity.

Specific inhibition of human cytomegalovirus glycoprotein B-mediated fusion by a novel thiourea small molecule

A novel small molecule inhibitor of human cytomegalovirus (HCMV) was identified as the result of screening a chemical library by using a whole-virus infected-cell assay. Synthetic chemistry efforts yielded the analog designated CFI02, a compound whose potency had been increased about 100-fold over an initial inhibitor. The inhibitory concentration of CFI02 in various assays is in the low nanomolar range. CFI02 is a selective and potent inhibitor of HCMV; it has no activity against other CMVs, alphaherpesviruses, or unrelated viruses. Mechanism-of-action studies indicate that CFI02 acts very early in the replication cycle, inhibiting virion envelope fusion with the cell plasma membrane. Mutants resistant to CFI02 have mutations in the abundant virion envelope glycoprotein B that are sufficient to confer resistance. Taken together, the data suggest that CFI02 inhibits glycoprotein B-mediated HCMV virion fusion. Furthermore, CFI02 inhibits the cell-cell spread of HCMV. This is the first study of a potent and selective small molecule inhibitor of CMV fusion and cell-cell spread.

Antiviral effect of chinonin against herpes simplex virus

In order to investigate the antiviral effect of chinonin against Herpes simplex virus (HSV), the encephalitis model in mice and skin infection model in guinea pigs were established by HSV- I and HSV-II infection respectively. Acyclovir was used as the positive reference drug to evaluate the antiviral capacity of chinonin. Chinonin showed an obvious therapeutic effect on encephalitis in mice at doses of 25 and 50 mg/kg. At both dosages, chinonin demonstrated stronger protection than acyclovir (1 and 5 mg/kg) to the infected mice from death. It was also found that chinonin could treat the skin infection in guinea pigs effectively. The therapeutic effect of chinonin was similar to that of acyclovir (5 mg/kg) at 25 mg/kg but obviously better than that at 50 and 75 mg/ kg. In conclusion, chinonin is a potential candidate for the treatment against HSV.