Synthesis and biological evaluation of novel rhodanine-based structures with antiviral activity towards HHV-6 virus.

An increased awareness of diseases associated with Human herpesvirus 6 (HHV-6) infection or reactivation has resulted in a growing interest in the evaluation of the best treatment options available for the clinical management of HHV-6 disease. However, no compound has yet been approved exclusively for HHV-6 infection treatment. For this reason, the identification of anti-HHV6 compounds provides a valuable opportunity for developing efficient antiviral therapies. A possible target for antiviral drugs is the virus-cell fusion step. In this study, we synthetized potential fusion intermediates inhibitors based on the rhodanine structure. The obtained derivatives were tested for cytotoxicity and for antiviral activity in human cells infected with HHV6. Level of infection was monitored by viral DNA quantification at different time points up to 7 days post infection. Among the synthetized derivatives, 9e showed a significative inhibitory effect on viral replication that lasted over 7 days, probably attributable to the particular combination of hydrophilic and hydrophobic substituents to the rhodanine moiety. Our results support the use of these amphipathic fusion inhibitors for the treatment of HHV-6 infections.

Effects of Prophylactic Foscarnet on Human Herpesvirus-6 Reactivation and Encephalitis in Cord Blood Transplant Recipients: A Prospective Multicenter Trial with an Historical Control Group.

Cord blood transplantation (CBT) is a distinct risk factor for human herpesvirus-6 (HHV-6) reactivation and HHV-6 encephalitis. In a prospective multicenter trial we investigated the effects of prophylactic foscarnet (90 mg/kg i.v. infusion from days 7 to 27 after CBT) on the occurrence of HHV-6 reactivation, HHV-6 encephalitis, and acute graft-versus-host disease (aGVHD) in CBT recipients. Between 2014 and 2016, 57 patients were included in a foscarnet-prophylaxis group. Outcomes were compared with an historical control group who received CBT between 2010 and 2014 (standard-treatment group, n = 63). The cumulative incidence of high-level HHV-6 reactivation, defined as plasma HHV-6 DNA ≥ 104 copies/mL, at 60 days after CBT was significantly lower in the foscarnet-prophylaxis group than in the standard-treatment group (18.3% versus 57.3%, P < .001). Multivariate analysis revealed that myeloablative preconditioning and standard treatment were significant risk factors for high-level HHV-6 reactivation. The cumulative incidence of HHV-6 encephalitis at 60 days after CBT was not different between the groups (foscarnet-prophylaxis group, 12.4%; standard-treatment group, 4.9%; P = .14). The cumulative incidences of grades II to IV and grades III to IV aGVHD at 60 days after CBT were not different between the groups (grades II to IV aGVHD: foscarnet-prophylaxis group, 42.0%; standard-treatment group, 40.5%; P = .96; grades III to IV aGVHD: foscarnet-prophylaxis group, 14.5%; standard-treatment group, 14.5%; P = 1.00). In the setting of this study foscarnet significantly suppressed systemic HHV-6 reactivation in CBT recipients but failed to prevent the development of HHV-6 encephalitis. Suppression of HHV-6 reactivation by foscarnet did not show any effects against the incidence of aGVHD.

HHV-6 in liver transplantation: A literature review.

Human herpesvirus 6 (HHV-6A and HHV-6B) can cause primary infection or reactivate from latency in liver transplant recipients, which can result in a variety of clinical syndromes, including fever, hepatitis, encephalitis and higher rates of graft dysfunction as well as indirect effects including increased risks of mortality, CMV disease, hepatitis C progression and greater fibrosis scores. Although HHV-6 infection is currently diagnosed by quantifying viral DNA in plasma or blood, biopsy to demonstrate histopathological effects of HHV-6 remains the gold standard for diagnosis of end-organ disease. HHV-6 reactivation may be restricted to the infected organ with no evidence of active infection in the blood. HHV-6 infections in liver transplant patients are mostly asymptomatic, but clinically significant tissue-invasive infections have been treated successfully with ganciclovir, foscarnet or cidofovir. Inherited chromosomally integrated HHV-6 (ciHHV-6), in either the recipient or the donor organ, may create confusion about systemic HHV-6 infection. Recipients with inherited ciHHV-6 may have an increased risk of opportunistic infection and graft rejection. This article reviews the current scientific data on the clinical effects, risk factors, pathogenesis, diagnosis and treatment of HHV-6 infections in liver transplant recipients.

Successful treatment and FDG-PET/CT monitoring of HHV-6 encephalitis in a non-neutropenic patient: case report and literature review.

Human herpesvirus (HHV)-6 reactivation is associated with severe forms of encephalitis among patients undergoing hematopoietic stem cell transplantation. Cases in non-neutropenic patients are uncommon. The efficacy of ganciclovir and other compounds that are used for the treatment of HHV-6 encephalitis remains suboptimal and linked to toxicity. Valganciclovir, the oral prodrug of ganciclovir, could be practical to treat outpatients, but it is not commonly used for severe cases. We report a case of HHV-6 encephalitis in a non-neutropenic patient successfully treated with valganciclovir and undergoing therapeutic drug monitoring in plasma and in the cerebrospinal fluid. Resolution of infectious foci was documented by cerebral MRI and F18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). A review of the literature on HHV-6 encephalitis is also reported.

The use of heparin in infertility and recurrent pregnancy loss: Are its antiviral properties at play?

Recently, human herpesvirus 6 (HHV-6) has been implicated in cases of poor pregnancy outcomes. The ability of HHV-6 to disrupt endothelial cell functioning may inhibit the creation of an appropriate uterine environment for implantation and fetal development, resulting in infertility and pregnancy loss, among other complications. Heparin has been used to treat pregnant women who are predisposed to thrombosis, and it has also been used in some women with infertility or recurrent pregnancy loss without associated thrombotic events. Positive pregnancy outcomes after heparin treatment in these groups indicate that heparin may alter the uterine environment to make it more suitable for implantation and fetal growth. In this paper, we propose that in some cases, heparin may accomplish this by inhibiting HHV-6 transfer to the endometrium and/or by offsetting the virally-mediated effects of endothelial cell injury.

Anti-herpesviral effects of a novel broad range anti-microbial quaternary ammonium silane, K21.

We have created a novel quaternary ammonium silane, K21 through sol-gel chemistry, using an ethoxylated version of an organosilane quaternary ammonium compound and TetraEthyl Ortho Silicate (TEOS) as precursors. Previous studies using the precursor molecule quaternary ammonium compounds (QACs) and a methacryloxy version of K21, primarily designed for use in dental healthcare, have shown inhibited growth properties against several types of gram-positive and gram-negative bacteria including Escherichia coli, Streptococcus mutans, Actinomyces naeslundii and Candida albicans etc. Here we tested the effect of K21 on HSV-1, HHV-6A and HHV-7 in in vitro cell culture infection models. Our results show growth inhibitory effect of K21 on HSV-1, HHV-6A and HHV-7 infection.

Human herpesvirus 6B reactivation and delirium are frequent and associated events after cord blood transplantation.

Human herpesvirus 6B (HHV-6B) frequently reactivates after cord blood transplantation (CBT). We previously reported an association between HHV-6B reactivation and delirium after hematopoietic cell transplantation. In this prospective study, 35 CBT recipients underwent twice-weekly plasma PCR testing for HHV-6 and thrice-weekly delirium assessment until day 84. There was a quantitative association between HHV-6B reactivation and delirium in univariable (odds ratio, 2.88; 95% confidence interval (CI), 0.97-8.59) and bivariable models. In addition, intensified prophylaxis with high-dose valacyclovir mitigated HHV-6B reactivation (adjusted hazard ratio, 0.39; 95% CI, 0.14-1.08). Larger trials are needed to explore the utility of HHV-6B prophylaxis after CBT.

Antiviral drug resistance in herpesviruses other than cytomegalovirus.

The discovery of acyclovir (ACV), a nucleoside analogue, more than 30 years ago, represents a milestone in the management of HSV and VZV infections. The modest activity of ACV against CMV prompted the development of another nucleoside analogue, ganciclovir, for the management of systemic and organ-specific CMV diseases. Second-line agents such as the pyrophosphate analogue foscarnet and the nucleotide analogue cidofovir have been approved subsequently. In contrast to ACV and ganciclovir, the latter drugs do not require selective phosphorylation by viral protein kinases to be converted into their active forms. Since the introduction of these antivirals, the emergence of drug-resistant mutants has been constantly reported particularly in severely immunocompromised patients such as bone marrow and solid organ transplant recipients as well as HIV-infected individuals. In this manuscript, we discuss the characteristics of the antiviral agents currently approved for the management of HSV, VZV and CMV diseases. In recent years, the resistance of CMV to antiviral drugs has been extensively reviewed. The emergence of antiviral drug resistance is also observed with other members of the Herpesviridae family, namely HSV-1, HSV-2, VZV and HHV-6, which are the focus of this review. More specifically, we describe the laboratory methods for assessing drug susceptibilities, the frequency and clinical significance of drug-resistant infections and their management.

Occupational trichloroethylene hypersensitivity syndrome: human herpesvirus 6 reactivation and rash phenotypes.

BACKGROUND: Trichloroethylene (TCE) is an industrial solvent which can cause severe generalized dermatitis, i.e., occupational TCE hypersensitivity syndrome. Reactivation of latent human herpesvirus 6 (HHV6) can occur in such patients, which has made TCE known as a causative chemical of drug-induced hypersensitivity syndrome (DIHS). OBJECTIVE: This study aimed to clarify HHV6 status, cytokine profiles and their association with rash phenotypes in patients with TCE hypersensitivity syndrome. METHODS: HHV6 DNA copy numbers, anti-HHV6 antibody titers, and cytokines were measured in blood prospectively sampled 5-7 times from 28 hospitalized patients with the disease. RESULTS: The patients (19 had exfoliative dermatitis (ED) and 9 had non-ED type rash) generally met the diagnostic criteria for DIHS. Viral reactivation defined as increases in either HHV6 DNA (≥100 genomic copies/10(6) peripheral blood mononuclear cells) or antibody titers was identified in 24 (89%) patients. HHV6 DNA, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-5, IL-6 and IL-10 concentrations were remarkably higher in the patients than in the healthy workers (p<0.01). Positive correlations between HHV6 DNA, TNF-α, IFN-γ, IL-6 and IL-10 were significant (p<0.05) except for that between HHV6 DNA and IFN-γ. An increase in HHV6 DNA was positively associated with an increase in TNF-α on admission (p<0.01). HHV6 DNA, the antibody titers, TNF-α and IL-10 concentrations were significantly higher in ED than in the non-ED type (p<0.05). CONCLUSION: Reactivated HHV6 and the increased cytokines could be biomarkers of TCE hypersensitivity syndrome. The higher-level reactivation and stronger humoral responses were associated with ED-type rash.

Synthesis and antiviral activities of methylenecyclopropane analogs with 6-alkoxy and 6-alkylthio substitutions that exhibit broad-spectrum antiviral activity against human herpesviruses.

Methylenecyclopropane nucleosides have been reported to be active against many of the human herpesviruses. The most active compound of this class is cyclopropavir (CPV), which exhibits good antiviral activity against human cytomegalovirus (HCMV), Epstein-Barr virus, both variants of human herpesvirus 6, and human herpesvirus 8. CPV has two hydroxymethyl groups on the methylenecyclopropane ring, but analogs with a single hydroxymethyl group, such as the prototypical (S)-synguanol, are also active and exhibit a broader spectrum of antiviral activity that also includes hepatitis B virus and human immunodeficiency virus. Here, a large set of monohydroxymethyl compounds with ether and thioether substituents at the 6 position of the purine was synthesized and evaluated for antiviral activity against a range of human herpesviruses. Some of these analogs had a broader spectrum of antiviral activity than CPV, in that they also inhibited the replication of herpes simplex viruses 1 and 2 and varicella-zoster virus. Interestingly, the antiviral activity of these compounds appeared to be dependent on the activity of the HCMV UL97 kinase but was relatively unaffected by the absence of thymidine kinase activity in HSV. These data taken together indicate that the mechanism of action of these analogs is distinct from that of CPV. They also suggest that they might be useful as broad-spectrum antiherpesvirus agents and may be effective in the treatment of resistant virus infections.

First therapeutic use of Artesunate in treatment of human herpesvirus 6B myocarditis in a child.

BACKGROUND: Human herpesvirus 6 (HHV-6) is an important cause of fulminant or acute viral myocarditis. However, insufficiency of standard antiviral treatment against HHV-6 is an emerging problem. OBJECTIVES: To describe the case of child with HHV-6 myocarditis who was treated by unloading with a left ventricular assist device and Artesunate. STUDY DESIGN: Case report supported by histological and viral diagnoses via a combination of histology/immunohistochemistry and polymerase chain reaction techniques performed on cardiac tissues before and after treatment. RESULTS: Following therapeutic intervention, the clinical status and heart function improved. Endomyocardial biopsies revealed decreased levels of HHV-6B DNA in the myocardium and the disappearance of histological findings in support of lymphocytic myocarditis. Left ventricular assist device could be explanted. No adverse effects of Artesunate were noted. CONCLUSIONS: In addition to existing heart failure treatments, Artesunate can be considered as an effective candidate for clinical use in cases of HHV-6B associated myocarditis.

Drug-induced severe adverse reaction enhanced by human herpes virus-6 reactivation.

Reactivation of certain latent viruses has been linked with a more severe course of drug-induced hypersensitivity reaction (HSR). For example, reactivation of human herpes virus (HHV)-6 is associated with severe organ involvement and a prolonged course of disease. The present study discusses an HSR developed in a previously healthy male exposed to ceftriaxone, doxycycline, vancomycin, and trimethoprim/sulfamethoxazole (co-trimoxazole; TMP/SMX). Initially, the patient presented clinical manifestations of HSR, as well as clinical and laboratory measurements compatible with liver and renal failure. Moreover, the patient presented skin desquamation compatible with Stevens-Johnson syndrome (SJS)/toxic epidermal necrolysis. During the reaction, it was observed HHV-6 reactivation. The severity of clinical symptoms is correlated with HHV-6 titer, as well as with results of the in vitro lymphocyte toxicity assay (LTA). Serum levels of a large panel of cytokines are compared between the patient, a large population of SJS patients, and a cohort of healthy controls, using data collected by our laboratory over the years. HHV-6 was measured in the cell culture media from lymphocytes incubated with each of the 4 drugs. Moreover, we describe a new assay using cytokines released by patient lymphocytes following in vitro exposure to the incriminated drugs as biomarkers of HSR. Based on LTA results, HHV-6 reactivation and cytokine measurements, we establish that only doxycycline and TMP/SMX were involved in the HSR. As result of this analysis, the patient could continue to use the other 2 antibiotics safely.

Evaluation of Epstein-Barr virus, human herpesvirus 6 (HHV-6), and HHV-8 antiviral drug susceptibilities by use of real-time-PCR-based assays.

Evaluation of candidate antiviral drugs against Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and HHV-8 is hampered by the lack of convenient laboratory assays. We developed real-time quantitative PCR assays performed on supernatants of lymphoma cell lines and determined the 50% inhibitory concentrations (IC50s) of nucleoside, nucleotide, and pyrophosphate analogues against these herpesviruses.