Ganciclovir. An update of its therapeutic use in cytomegalovirus infection

Antiviral treatment for viral pneumonia: current drugs and natural compounds

In recent years, viral pneumonia has become a significant challenge to global public health, particularly during the COVID-19 pandemic. Viral pneumonia can be caused by various viruses, including influenza virus, RSV, and adenovirus. These viruses trigger inflammatory responses by invading the respiratory epithelial cells, leading to lung damage. Existing antiviral drugs such as ribavirin, adobiravir, and oseltamivir exert their therapeutic effects by inhibiting different stages of the viral life cycle but face issues such as increasing drug resistance. Natural components like astragalus saponins, Houttuynia cordata flavonoids, and tea theaflavin-gallates have demonstrated supportive roles in antiviral treatments, capable of not only enhancing immune responses but also potentially inhibiting viral replication through multiple pathways, thereby alleviating lung damage. Although natural components cannot entirely replace traditional antiviral drugs, their role in comprehensive treatment regimens is becoming increasingly important. This review summarizes the current applications and limitations of antiviral drugs and explores the research progress and potential mechanisms of natural components in the treatment of viral pneumonia.

Antiviral therapy for cytomegalovirus retinitis: A systematic review and meta-analysis

Cytomegalovirus retinitis (CMVR) is a significant cause of blindness in patients with advanced acquired immunodeficiency syndrome (AIDS). There are no established guidelines for its treatment, resulting in varied antiviral approaches. We pooled data from 59 studies (4501 patients) to evaluate treatment variations and outcomes (CRD42022321088). Overall pooled estimates showed visual acuity improvement at 18 % (95 % CI: 7-41 %), inflammation resolution at 90 % (95 % CI: 81-95 %), retinal detachment at 11 % (95 % CI: 8-14 %), and recurrence at 19 % (95 % CI: 11-31 %). The main antiviral treatment approaches identified were: (1) intravenous antivirals alone in 33 studies, (2) intravitreal antivirals alone in 26 studies, (3) oral antivirals alone in 3 studies, and (4) a combination of systemic (oral or intravenous[IV]) and intravitreal antivirals in 7 studies, with varying schemes and durations. Ganciclovir was the predominant antiviral, with intravenous administration being the most reported (in 23 studies), followed by intravitreal administration (in 20 studies). While visual acuity improvement was comparable, inflammation resolution tended to be higher with intravitreal than with IV antivirals, though not statistically significant (88 %, 95 % CI: 69-96 % vs 75 %, 95 % CI: 35-94 %, p = 0.38). Retinitis progression rate for IV ganciclovir was lower than for those without ganciclovir. Inflammation recurrence was significantly lower in antiretroviral (ART)-treated compared to non-ART-treated HIV/AIDS patients (10 % (95 % CI: 4-20 %) vs 33 % (95 % CI: 19-50 %), p < 0.01). Neutropenia, particularly with ganciclovir, was the most reported adverse effect (up to 50 %).

Advancing Green Chemistry in Antiviral Therapeutics: A Comprehensive Review

Cytomegalovirus (CMV) is a prevalent virus across the world that belongs to the family Herpesviridae but remains dormant in the body unless the immune system is compromised. In addition, when the bacterium is compromised without any health risks, the infection spreads from one person to another person through body fluids, such as saliva, blood, etc. Ganciclovir is an anti- viral medication used in treating viral infections, especially in the treatment of CMV in people with acquired immune deficiency syndrome and immunity at risk. The quality control of ganciclovir in industries is carried out by using anti-green solvents in large volumes; these solvents are not safe in consideration of environmental factors and analysts. Also, the waste generation by these solvents causes hazardous effects on the environment. Further, using 12 green analytical chemistry principles promotes the awareness of analytical judgments among the research groups. It is a revolutionary step in the analytical field to enhance the safety of the environment, and analysts, apart from safety, help to control waste production and conserve energy-reducing occupational hazards. Many works have been carried out for the quality control of ganciclovir using different solvents, such as acetonitrile, methanol, etc. Despite this, there are no existing methods with green solvents or procedures to reduce energy and waste generation. Therefore, the purpose of this review is to understand the drug profile of ganciclovir and the methods developed.

Efficacy of Letermovir for Cytomegalovirus Prophylaxis Following Alemtuzumab T-Cell Depleted Allogeneic Hematopoietic Stem Cell Transplant

In vivo T-cell depletion (TCD) using alemtuzumab decreases the risk of Graft vs Host Disease (GvHD) in recipients of allogeneic hematopoietic stem cell transplant (allo-HSCT). However, this approach increases the risk of infections post-allo-HSCT, including Cytomegalovirus (CMV). Letermovir is approved for the use in CMV prophylaxis post-allo-HSCT. Few studies have investigated the efficacy of letermovir in patients receiving alemtuzumab. This is a single-center retrospective study describing our institutional experience using letermovir in recipients of alemtuzumab TCD allo-HSCT from unrelated donors (URD). The primary outcome was the cumulative incidence of significant CMV infection (defined as viremia leading to preemptive antiviral therapy or CMV disease) within 100 days post-transplant. Secondary outcomes included the cumulative incidence of acute GvHD (grade ≥ 2), the cumulative incidence of extensive chronic GvHD, and overall survival. A total of 84 alemtuzumab TCD URD allo-HSCT recipients were included in the analysis, 30 of whom received letermovir (letermovir group) and 54 who did not receive letermovir (control group). The median age was 59 years (range: 26-75 years) and 55.5 years (range: 20-73 years) in the letermovir and control group, respectively. Most recipients (66.7%) in both groups received unrelated matched allografts, and myeloid neoplasms were the most common indication for allo-HSCT. A significantly lower cumulative incidence of significant CMV infection within 100 days was seen in the letermovir group compared to the control group (10.0% [95% CI: 2.5-23.9%] versus 55.6% [95% CI: 41.2-67.8%], P < .0001). There was no statistically significant difference in the incidence of acute GvHD (grade ≥ 2) or overall survival between the 2 groups. However, lower rates of extensive chronic GvHD were noted in the letermovir group (10.5% [95% CI: 2.6-24.9%] versus. 36.5% [95% CI: 23.6-49.5%], P = .0126). These results demonstrate the efficacy of letermovir in decreasing the rates of clinically significant CMV infection in patients undergoing alemtuzumab T-cell depleted allo-HSCT.

Treatment of Epstein-Barr Virus infection in immunocompromised patients

Epstein-Barr Virus (EBV), is a ubiquitous γ-Herpesvirus that infects over 95% of the human population and can establish a life-long infection without causing any clinical symptoms in healthy individuals by residing in memory B-cells. Primary infection occurs in childhood and is mostly asymptomatic, however in some young adults it can result in infectious mononucleosis (IM). In immunocompromised individuals however, EBV infection has been associated with many different malignancies. Since EBV can infect both epithelial and B-cells and very rarely NK cells and T-cells, it is associated with both epithelial cancers like nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC), with lymphomas including Burkitt Lymphoma (BL) or Post-transplant Lymphoproliferative Disorder (PTLD) and rarely with NK/T-cell lymphomas. Currently there are no approved antivirals active in PTLD nor in any other malignancy. Moreover, lytic phase disease almost never requires antiviral treatment. Although many novel therapies against EBV have been described, the management and/or prevention of EBV primary infections or reactivations remains difficult. In this review, we discuss EBV infection, therapies targeting EBV in both lytic and latent state with novel therapeutics developed that show anti-EBV activity as well as EBV-associated malignancies both, epithelial and lymphoproliferative malignancies and emerging therapies targeting the EBV-infected cells.

Safety and efficacy of weight-based ganciclovir dosing strategies in overweight/obese patients

BACKGROUND

The management of cytomegalovirus (CMV) is particularly challenging as both CMV and its usual first-line treatment, ganciclovir, are associated with neutropenia. Ganciclovir dosing is weight-based, most commonly utilizing total body weight (TBW). The subsequent high doses of ganciclovir in overweight/obese patients may increase the risk of toxicity. Utilizing adjusted body weight (AdjBW) dosing may help mitigate this risk. Therefore, the objective of this study was to evaluate the difference in toxicity and efficacy between TBW and AdjBW ganciclovir dosing strategies in overweight/obese patients.

METHODS

This retrospective study conducted safety and efficacy analyses of ganciclovir courses (≥72 h) used as CMV treatment. The primary safety outcome was the incidence of neutropenia (absolute neutrophil count <1000 cells/μL), and the primary efficacy outcome was a 2-log decrease in CMV polymerase chain reaction within 4 weeks following ganciclovir initiation. In both analyses, courses were excluded in which ganciclovir was dosed outside of specified renal dosing parameters for >20% of the course.

RESULTS

Among the 253 courses in the safety cohort, there was no difference in the incidence of neutropenia (17.4% vs. 13.5%, p = .50) in AdjBW compared to TBW dosing. In the 62 courses evaluating efficacy, there was no statistical difference between AdjBW and TBW dosing (60.0% vs. 45.2%, p = .28). No subgroups were identified in which AdjBW dosing was advantageous.

CONCLUSION

Utilization of AdjBW ganciclovir dosing did not result in decreased neutropenia or treatment efficacy as compared to TBW dosing. Further studies with larger patient populations would be beneficial to confirm these findings.

Antiviral Approach to Cytomegalovirus Infection: An Overview of Conventional and Novel Strategies

Human cytomegalovirus (HCMV) is a herpesvirus capable of establishing a lifelong persistence in the host through a chronic state of infection and remains an essential global concern due to its distinct life cycle, mutations, and latency. It represents a life-threatening pathogen for immunocompromised patients, such as solid organ transplanted patients, HIV-positive individuals, and hematopoietic stem cell recipients. Multiple antiviral approaches are currently available and administered in order to prevent or manage viral infections in the early stages. However, limitations due to side effects and the onset of antidrug resistance are a hurdle to their efficacy, especially for long-term therapies. Novel antiviral molecules, together with innovative approaches (e.g., genetic editing and RNA interference) are currently in study, with promising results performed in vitro and in vivo. Since HCMV is a virus able to establish latent infection, with a consequential risk of reactivation, infection management could benefit from preventive treatment for critical patients, such as immunocompromised individuals and seronegative pregnant women. This review will provide an overview of conventional antiviral clinical approaches and their mechanisms of action. Additionally, an overview of proposed and developing new molecules is provided, including nucleic-acid-based therapies and immune-mediated approaches.

Development of broadly neutralizing antibodies targeting the cytomegalovirus subdominant antigen gH

Human cytomegalovirus (HCMV) is a β-herpesvirus that increases morbidity and mortality in immunocompromised individuals including transplant recipients and newborns. New anti-HCMV therapies are an urgent medical need for diverse patient populations. HCMV infection of a broad range of host tissues is dependent on the gH/gL/gO trimer and gH/gL/UL28/UL130/UL131A pentamer complexes on the viral envelope. We sought to develop safe and effective therapeutics against HCMV by generating broadly-neutralizing, human monoclonal antibodies (mAbs) from VelocImmune® mice immunized with gH/gL cDNA. Following high-throughput binding and neutralization screening assays, 11 neutralizing antibodies were identified with unique CDR3 regions and a high-affinity (KD 1.4-65 nM) to the pentamer complex. The antibodies bound to distinct regions within Domains 1 and 2 of gH and effectively neutralized diverse clinical strains in physiologically relevant cell types including epithelial cells, trophoblasts, and monocytes. Importantly, combined adminstration of mAbs with ganciclovir, an FDA approved antiviral, greatly limited virus dissemination. Our work identifies several anti-gH/gL mAbs and sheds light on gH neutralizing epitopes that can guide future vaccine strategies.

Cytomegalovirus management after allogeneic hematopoietic stem cell transplantation: A mini-review

Because of the high incidence of cytomegalovirus (CMV) seropositivity in the population, CMV infection is a common and severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in Taiwan. Here we propose a CMV management strategy for patients undergoing allo-HSCT from the Taiwanese perspective, which focuses on the epidemiology, diagnosis, monitoring, prophylaxis, and treatment of CMV infection after allo-HSCT. In terms of CMV monitoring, weekly CMV monitoring with the COBAS® AmpliPrep system is the standard approach because the pp65 CMV antigenemia assay has a lower sensitivity than CMV monitoring with the COBAS® AmpliPrep system. However, pp65 CMV antigenemia assay has a better correlation with clinical symptoms in immunocompromised patients. A 14-week prophylactic course of letermovir is recommended for allo-HSCT recipients in Taiwan, especially for recipients of hematopoietic stem cells from mismatched unrelated and haploidentical donors. Preemptive ganciclovir therapy should be initiated when the CMV viral load exceeds 1000 copies/mL, and should not be discontinued until CMV DNA is no longer detected in the blood. For allo-HSCT recipients who have CMV-related diseases, ganciclovir with or without CMV-specific intravenous immunoglobulin is the standard of care. The limited availability of foscarnet, an alternative for patients who are not responsive to or cannot tolerate ganciclovir, is a crucial issue in Taiwan. For pediatric allo-HSCT recipients, more data are needed to propose a CMV management recommendation.

Optimization of Ganciclovir use in allogeneic hematopoietic cell transplant recipients - the role of therapeutic drug monitoring

Introduction: Cytomegalovirus (CMV) is an opportunistic infectious complication that can occur after allogeneic hematopoietic cell transplantation (HCT). The mainstay of treatment and prevention of this infection is ganciclovir and its ester prodrug valganciclovir. There is conflicting evidence on the clinical utility of routine ganciclovir therapeutic drug monitoring (TDM) as a means to optimize treatment.Areas covered: This review aims to describe the current knowledge of the pharmacokinetic and pharmacodynamic characteristics of ganciclovir and valganciclovir, and to explore the evidence and challenges surrounding ganciclovir TDM within the allogeneic HCT cohort.Expert opinion: Ganciclovir TDM is important to optimize efficacy in selected patient groups where there are variable pharmacokinetic factors or inadequate response to treatment. However, defined pharmacokinetic exposures which correlate with treatment efficacy and toxicity remain elusive. Prospective clinical studies in specific patient groups are required to clarify this issue. Alternative TDM targets such as the intracellular ganciclovir triphosphate should be explored as they may prove to have better correlation with clinical outcomes and adverse effects. With recent advances in CMV immune monitoring, novel approaches integrating TDM with specific CMV immune phenotyping in a predictive model will be advantageous in optimizing ganciclovir dosing by combining TDM with a risk stratification approach.

COVID-19 therapy: What weapons do we bring into battle?

Urgent treatments, in any modality, to fight SARS-CoV-2 infections are desired by society in general, by health professionals, by Estate-leaders and, mainly, by the scientific community, because one thing is certain amidst the numerous uncertainties regarding COVID-19: knowledge is the means to discover or to produce an effective treatment against this global disease. Scientists from several areas in the world are still committed to this mission, as shown by the accelerated scientific production in the first half of 2020 with over 25,000 published articles related to the new coronavirus. Three great lines of publications related to COVID-19 were identified for building this article: The first refers to knowledge production concerning the virus and pathophysiology of COVID-19; the second regards efforts to produce vaccines against SARS-CoV-2 at a speed without precedent in the history of science; the third comprehends the attempts to find a marketed drug that can be used to treat COVID-19 by drug repurposing. In this review, the drugs that have been repurposed so far are grouped according to their chemical class. Their structures will be presented to provide better understanding of their structural similarities and possible correlations with mechanisms of actions. This can help identifying anti-SARS-CoV-2 promising therapeutic agents.

Acyclovir in the Treatment of Herpes Viruses – A Review

Background:

Herpes Simplex (HSV) viruses are widely spread, highly contagious human pathogens. The statistics indicate that 50-90% of adults worldwide are seropositive for these viruses, mainly HSV-1 and HSV-2. The primary infection results in the appearance of watery blisters (cold sores) on the skin, lips, tongue, buccal mucosa or genitals. The ocular infection is the major cause of corneal blindness in the Western World. Once the HSV virus enters human body, it cannot be completely eradicated because HSV viruses are able to change into their latent form which can survive the treatment. The viron resides in trigeminal ganglia of the host, who becomes vulnerable to the reoccurrence of the disease during the whole lifespan. The neurotropic and neuro-invasive properties of HSV are responsible for neurodegenerative illnesses, such as Alzheimer's disease. Acyclovir and its analogues, being the inhibitors of the viral DNA replication, are the only approved medicines for HSV infection therapies.

Objective:

The current paper presents the up-to-date overview of the important pharmacological features of acyclovir, its analogues and their delivery systems including the mechanism of action, routes of administration, absorption and metabolism, as well as side effects of the therapy.

Conclusion:

Acyclovir remains the gold standard in the treatment of herpes virus infections, mainly due to the emerging of the new delivery systems improving considerably its bioavailability. The analogues of acyclovir, especially their esters, characterized by significantly higher bioavailability and safety, may gradually replace acyclovir in selected applications.

Current Antivirals and Novel Botanical Molecules Interfering With Herpes Simplex Virus Infection

Herpes simplex viruses type 1 (HSV-1) and type 2 (HSV-2) are highly prevalent within the human population and are characterized by lifelong infections and sporadic recurrences due to latent neuron infection. Upon reactivations, HSVs may manifest either, symptomatically or asymptomatically and be shed onto others through mucosae body fluids. Although, HSVs can produce severe disease in humans, such as life-threatening encephalitis and blindness, the most common symptoms are skin and mucosal lesions in the oro-facial and the genital areas. Nucleoside analogs with antiviral activity can prevent severe HSV infection, yet they are not very effective for treating skin manifestations produced by these viruses, as they only reduce in a few days at most the duration of lesions. Additionally, HSV variants that are resistant to these antivirals may arise, especially in immunosuppressed individuals. Thus, new antivirals that can reduce the severity and duration of these cutaneous manifestations would certainly be welcome. Here, we review currently available anti-herpetic therapies, novel molecules being assessed in clinical trials and new botanical compounds reported in the last 20 years with antiviral activities against HSVs that might represent future treatments against these viruses.

π-Hole Interactions Involving Nitro Aromatic Ligands in Protein Structures

Studying noncanonical intermolecular interactions between a ligand and a protein constitutes an emerging research field. Identifying synthetically accessible molecular fragments that can engage in intermolecular interactions is a key objective in this area. Here, it is shown that so-called "π-hole interactions" are present between the nitro moiety in nitro aromatic ligands and lone pairs within protein structures (water and protein carbonyls and sulfurs). Ample structural evidence was found in a PDB analysis and computations reveal interaction energies of about -5 kcal mol-1 for ligand-protein π-hole interactions. Several examples are highlighted for which a π-hole interaction is implicated in the superior binding affinity or inhibition of a nitro aromatic ligand versus a similar non-nitro analogue. The discovery that π-hole interactions with nitro aromatics are significant within protein structures parallels the finding that halogen bonds are biologically relevant. This has implications for the interpretation of ligand-protein complexation phenomena, for example, involving the more than 50 approved drugs that contain a nitro aromatic moiety.

Advances in Antiplatelet Therapy for Dentofacial Surgery Patients: Focus on Past and Present Strategies

BACKGROUND

Nowadays, patients involved in antiplatelet therapy required special attention during oral surgery procedures, due to the antiplatelet drugs assumption. The motivations of the assumption may be different and related to the patient's different systemic condition. For this reason, accordingly to the current international guidelines, different protocols can be followed. The aim of this work is to analyze how the dentist's approach to these patients has changed from the past to the present, evaluating the risk exposure for the patients.

METHODS

This review paper considered different published papers in literature through quoted scientific channels, going in search of "ancient" works in such a way as to highlight the differences in the protocols undertaken. The analyzed manuscripts are in the English language, taking into consideration reviews, case reports, and case series in such a way as to extrapolate a sufficient amount of data and for evaluating the past therapeutic approaches compared to those of today.

RESULTS

Colleagues in the past preferred to subject patients to substitution therapy with low molecular weight anticoagulants, by suspending antiplatelet agents to treatment patients, often for an arbitrary number of days. The new guidelines clarify everything, without highlighting an increased risk of bleeding during simple oral surgery in patients undergoing antiplatelet therapy.

CONCLUSION

Either patients take these medications for different reasons, because of cardiovascular pathologies, recent cardiovascular events, or even for simple prevention, although the latest research shows that there is no decrease of cardiovascular accidents in patients who carry out preventive therapy. Surely, it will be at the expense of the doctor to assess the patient's situation and risk according to the guidelines. For simple oral surgery, it is not necessary to stop therapy with antiplatelet agents because the risk of bleeding has not increased, and is localized to a post-extraction alveolus or to an implant preparation, compared to patients who do not carry out this therapy. From an analysis of the results it emerges that the substitutive therapy should no longer be performed and that it is possible to perform oral surgery safely in patients who take antiplatelet drugs, after a thorough medical history. Furthermore, by suspending therapy, we expose our patients to more serious risks, concerning their main pathology, where present.

Pharmacokinetic drug evaluation of letermovir prophylaxis for cytomegalovirus in hematopoietic stem cell transplantation

INTRODUCTION

Letermovir is a new antiviral approved to prevent cytomegalovirus infection in hematopoietic stem cell transplant recipients. It has a distinct mechanism of action as it acts as a terminase complex inhibitor, and shows some advantages compared to the current treatment options for cytomegalovirus infection. Areas covered: This review focuses on the efficacy, safety, pharmacokinetics, pharmacodynamics, and drug-drug interactions of letermovir. Expert opinion: Letermovir is a new antiviral to prevent cytomegalovirus infection. Unlike the currently used polymerase inhibitors, it has a distinct mechanism of action with better safety, limited resistance, and no cross-resistance. Although a lot of research on pharmacokinetics and drug-drug interactions has already been performed, it might be useful to clarify the effect of letermovir on voriconazole exposure, the drug-drug interaction between caspofungine and letermovir and the effect of statins on letermovir exposure. Also, the lack of an exposure-response relationship should be confirmed in large real-life post-marketing studies in order to be able to lower the intravenous dose of letermovir.

Antiviral Therapies for Herpesviruses: Current Agents and New Directions

PURPOSE

The objective of this review was to summarize the recent literature describing the current burden of disease due to herpesviruses in the antiviral and transplant era; describe mechanisms of action of antiviral agents and the development of resistance; summarize the literature of recent antiviral agents brought to market as well as agents under development; and to present literature on future strategies for herpesvirus therapeutics.

METHODS

An extensive search of the medical literature related to antiherpesviral therapy was conducted to compose this narrative review. Literature searches were performed via PubMed and ultimately 137 articles were included as most relevant to the scope of this article.

FINDINGS

Herpesviruses are a family of DNA viruses that are ubiquitous throughout human populations and share the feature of establishing lifelong infections in a latent phase with the potential of periodic reactivation. With the exception of herpes simplex virus, varicella zoster virus, and Epstein-Barr virus, which have a significant disease burden in individuals with normal immune function, the morbidity and mortality of the remaining viruses are primarily associated with the immunocompromised host. Over the last half-century, several agents have been tested in large randomized, placebo-controlled trials that have resulted in safe and effective antiviral agents for the treatment of many of these infections.

IMPLICATIONS

With increasing use of antiherpesviral agents for extended periods, particularly in immunocompromised hosts, the emergence of resistant viruses has necessitated the development of newer agents with novel targets and better side-effect profiles.

Ganciclovir

Ganciclovir is synthetic nucleoside analog of guanine closely related to acyclovir but has greater activity against cytomegalovirus. This comprehensive profile on ganciclovir starts with a description of the drug: nomenclature, formulae, chemical structure, elemental composition, and appearance. The uses and application of the drug are explained. The methods that were used for the preparation of ganciclovir are described and their respective schemes are outlined. The methods which were used for the physical characterization of the dug are: ionization constant, solubility, X-ray powder diffraction pattern, crystal structure, melting point, and differential scanning calorimetry. The chapter contains the spectra of the drug: ultraviolet spectrum, vibrational spectrum, nuclear magnetic resonance spectra, and the mass spectrum. The compendial methods of analysis of ganciclovir include the United States Pharmacopeia methods. Other methods of analysis that were reported in the literature include: high-performance liquid chromatography alone or with mass spectrometry, electrophoresis, spectrophotometry, voltammetry, chemiluminescence, and radioimmunoassay. Biological investigation on the drug includes: pharmacokinetics, metabolism, bioavailability, and biological analysis. Reviews on the methods used for preparation or for analysis of the drug are provided. The stability of the drug in various media and storage conditions is reported. More than 240 references are listed at the end of the chapter.

Biophysical and In Silico Studies of the Interaction between the Anti-Viral Agents Acyclovir and Penciclovir, and Human Serum Albumin

Acyclovir (ACV) and penciclovir (PNV) have been commonly used during the last few decades as potent antiviral agents, especially for the treatment of herpes virus infections. In the present research their binding properties with human serum albumin (HSA) were studied using different advanced spectroscopic and in-silico methods. The interactions between ACV/PNV and HSA at the three investigated temperatures revealed a static type of binding. Extraction of the thermodynamic parameters of the ACV-HSA and PNV-HSA systems from the measured spectrofluorimetric data demonstrated spontaneous interactions with an enthalpy change (∆H⁰) of −1.79 ± 0.29 and −4.47 ± 0.51 kJ·mol⁻¹ for ACV and PNV, respectively. The entropy change (∆S⁰) of 79.40 ± 0.95 and 69.95 ± 1.69 J·mol⁻¹·K⁻¹ for ACV and PNV, respectively, hence supported a potential contribution of electrostatic binding forces to the ACV-HSA and PNV-HSA systems. Putative binding of ACV/PNV to HSA, using previously reported site markers, showed that ACV/PNV were bound to HSA within subdomains IIA and IIIA (Sudlow sites I and II). Further confirmation was obtained through molecular docking studies of ACV-HSA and PNV-HSA binding, which confirmed the binding site of ACV/PNV with the most stable configurations of ACV/PNV within the HSA. These ACV/PNV conformers were shown to have free energies of −25.61 and −22.01 kJ·mol⁻¹ for ACV within the HSA sites I and II and −22.97 and −26.53 kJ·mol⁻¹ for PNV in HSA sites I and II, with hydrogen bonding and electrostatic forces being the main binding forces in such conformers.

Pharmacokinetics and Safety of Letermovir Coadministered With Cyclosporine A or Tacrolimus in Healthy Subjects

Letermovir is being developed for human cytomegalovirus infection treatment and prophylaxis. In patients receiving transplants, antivirals are coadministered with cyclosporine A (CsA) or tacrolimus (TAC) immunosuppressants. Therefore, we investigated the potential for letermovir-immunosuppressant interactions. In 2 phase 1 clinical trials either CsA 50 mg or TAC 5 mg was administered to healthy males. Following washout, letermovir 80 mg was dosed twice daily for 7 and 11 days in the CsA and TAC trials, respectively, with a second dose of immunosuppressant coadministered with letermovir at steady state. In addition, letermovir 40 mg twice daily was administered for 14 days, and either CsA 50 or 200 mg administered on days 7 and 14. Pharmacokinetics and tolerability were assessed. Letermovir increased CsA and TAC C_max by 37% and 70%, respectively, and exposure by 70% and 78%, respectively, compared with immunosuppressant alone; t_½ was also increased from 10.7 to 17.9 hours for CsA. CsA (50/200 mg) increased letermovir C_max,ss (109%/167%) and AUC_ss,τ (126%/237%) and decreased t_½ (4.33 to 3.68/3.04 hours) versus letermovir alone. TAC did not significantly affect letermovir pharmacokinetics. All treatments were well tolerated. Concomitant letermovir increased TAC and CsA exposure. CsA altered letermovir pharmacokinetics, whereas TAC did not.

Hyaluronic acid-nimesulide conjugates as anticancer drugs against CD44-overexpressing HT-29 colorectal cancer in vitro and in vivo

Carrier-mediated drug delivery systems are promising therapeutics for targeted delivery and improved efficacy and safety of potent cytotoxic drugs. Nimesulide is a multifactorial cyclooxygenase 2 nonsteroidal anti-inflammatory drug with analgesic, antipyretic and potent anticancer properties; however, the low solubility of nimesulide limits its applications. Drugs conjugated with hyaluronic acid (HA) are innovative carrier-mediated drug delivery systems characterized by CD44-mediated endocytosis of HA and intracellular drug release. In this study, hydrophobic nimesulide was conjugated to HA of two different molecular weights (360 kDa as HA with high molecular weight [HAH] and 43kDa as HA with low molecular weight [HAL]) to improve its tumor-targeting ability and hydrophilicity. Our results showed that hydrogenated nimesulide (N-[4-amino-2-phenoxyphenyl]methanesulfonamide) was successfully conjugated with both HA types by carbodiimide coupling and the degree of substitution of nimesulide was 1%, which was characterized by ¹H nuclear magnetic resonance 400 MHz and total correlation spectroscopy. Both Alexa Fluor^® 647 labeled HAH and HAL could selectively accumulate in CD44-overexpressing HT-29 colorectal tumor area in vivo, as observed by in vivo imaging system. In the in vitro cytotoxic test, HA-nimesulide conjugate displayed >46% cell killing ability at a nimesulide concentration of 400 µM in HT-29 cells, whereas exiguous cytotoxic effects were observed on HCT-15 cells, indicating that HA-nimesulide causes cell death in CD44-overexpressing HT-29 cells. Regarding in vivo antitumor study, both HAL-nimesulide and HAH-nimesulide caused rapid tumor shrinkage within 3 days and successfully inhibited tumor growth, which reached 82.3% and 76.4% at day 24 through apoptotic mechanism in HT-29 xenografted mice, without noticeable morphologic differences in the liver or kidney, respectively. These results indicated that HA-nimesulide with improved selectivity through HA/CD44 receptor interactions has the potential to enhance the therapeutic efficacy and safety of nimesulide for cancer treatment.

Comparison of three cell-based drug screening platforms for HSV-1 infection

Acyclovir (ACV) and its derivatives have been highly effective for treating recurrent, lytic infections with Herpes Simplex Virus, type 1 (HSV-1), but searches for additional antiviral drugs are motivated by recent reports of resistance to ACV, particularly among immunocompromised patients. In addition, the relative neurotoxicity of ACV and its inability to prevent neurological sequelae among HSV-1 encephalitis survivors compel searches for new drugs to treat HSV-1 infections of the central nervous system (CNS). Primary drug screens for neurotropic viruses like HSV-1 typically utilize non-neuronal cell lines, but they may miss drugs that have neuron specific antiviral effects. Therefore, we compared the effects of a panel of conventional and novel anti-herpetic compounds in monkey epithelial (Vero) cells, human induced pluripotent stem cells (hiPSCs)-derived neural progenitor cells (NPCs) and hiPSC-derived neurons (N = 73 drugs). While the profiles of activity for the majority of the drugs were similar in all three tissues, Vero cells were less likely than NPCs to identify drugs with substantial inhibitory activity in hiPSC-derived neurons. We discuss the relative merits of each cell type for antiviral drug screens against neuronal infections with HSV-1.

Treatment of alpha and beta herpesvirus infections in solid organ transplant recipients

INTRODUCTION

Human herpesviruses frequently cause infections in solid organ transplant (SOT) recipients. Areas covered: We provide an overview of the clinical impact of alpha and beta herpesviruses and highlight the mechanisms of action, pharmacokinetics, clinical indications, and adverse effects of antiviral drugs for the management of herpes simplex virus, varicella zoster virus and cytomegalovirus. We comprehensively evaluated key clinical trials that led to drug approval, and served as the foundation for management guidelines. We further provide an update on investigational antiviral agents for alpha and beta herpesvirus infections after SOT. Expert commentary: The therapeutic armamentarium for herpes infections is limited by the emergence of drug resistance. There have been major efforts for discovery of new drugs against these viruses, but the results of early-phase clinical trials have been less than encouraging. We believe, however, that more antiviral drug options are needed given the adverse side effects associated with current antiviral agents, and the emergence of drug-resistant virus populations in SOT recipients. Likewise, optimized use and strategies are needed for existing and novel antiviral drugs against alpha and beta-herpesviruses in SOT recipients.

Convallatoxin-Induced Reduction of Methionine Import Effectively Inhibits Human Cytomegalovirus Infection and Replication

Cytomegalovirus (CMV) is a ubiquitous human pathogen that increases the morbidity and mortality of immunocompromised individuals. The current FDA-approved treatments for CMV infection are intended to be virus specific, yet they have significant adverse side effects, including nephrotoxicity and hematological toxicity. Thus, there is a medical need for safer and more effective CMV therapeutics. Using a high-content screen, we identified the cardiac glycoside convallatoxin as an effective compound that inhibits CMV infection. Using a panel of cardiac glycoside variants, we assessed the structural elements critical for anti-CMV activity by both experimental and in silico methods. Analysis of the antiviral effects, toxicities, and pharmacodynamics of different variants of cardiac glycosides identified the mechanism of inhibition as reduction of methionine import, leading to decreased immediate-early gene translation without significant toxicity. Also, convallatoxin was found to dramatically reduce the proliferation of clinical CMV strains, implying that its mechanism of action is an effective strategy to block CMV dissemination. Our study has uncovered the mechanism and structural elements of convallatoxin, which are important for effectively inhibiting CMV infection by targeting the expression of immediate-early genes.

IMPORTANCE

Cytomegalovirus is a highly prevalent virus capable of causing severe disease in certain populations. The current FDA-approved therapeutics all target the same stage of the viral life cycle and induce toxicity and viral resistance. We identified convallatoxin, a novel cell-targeting antiviral that inhibits CMV infection by decreasing the synthesis of viral proteins. At doses low enough for cells to tolerate, convallatoxin was able to inhibit primary isolates of CMV, including those resistant to the anti-CMV drug ganciclovir. In addition to identifying convallatoxin as a novel antiviral, limiting mRNA translation has a dramatic impact on CMV infection and proliferation.

The Microtubule Inhibitor Podofilox Inhibits an Early Entry Step of Human Cytomegalovirus

Human cytomegalovirus is a ubiquitous β-herpesvirus that infects many different cell types through an initial binding to cell surface receptors followed by a fusion event at the cell membrane or endocytic vesicle. A recent high-throughput screen to identify compounds that block a step prior to viral gene expression identified podofilox as a potent and nontoxic inhibitor. Time-of-addition studies in combination with quantitative-PCR analysis demonstrated that podofilox limits an early step of virus entry at the cell surface. Podofilox was also able to drastically reduce infection by herpes simplex 1, an α-herpesvirus with a very similar entry process to CMV. Podofilox caused a reduced maximal plateau inhibition of infection by viruses with single step binding processes prior to fusion-like Newcastle disease virus, Sendai virus, and influenza A virus or viruses that enter via endocytosis like vesicular stomatitis virus and a clinical-like strain of CMV. These results indicate that microtubules appear to be participating in the post-binding step of virus entry including the pre- and post-penetration events. Modulation of the plasma membrane is required to promote virus entry for herpesviruses, and that podofilox, unlike colchicine or nocodazole, is able to preferentially target microtubule networks at the plasma membrane.

Surviving and fatal Elephant Endotheliotropic Herpesvirus-1A infections in juvenile Asian elephants - lessons learned and recommendations on anti-herpesviral therapy

Background

Elephant Endotheliotropic Herpesviruses (EEHVs) can cause acute haemorrhagic disease in young Asian elephants (Elephas maximus) and clinical EEHV infections account for the majority of their fatalities. The anti-herpesviral drug famciclovir (FCV) has been used routinely to treat viraemic at-risk elephants, but thus far without proven efficacy. This paper presents clinical and virological investigations of two EEHV-1A infected elephants treated with FCV, and discusses anti-herpesvirus therapies of viraemic elephants.

Cases presentations

Two 1.5 year old male Asian elephants at a zoological collection in the UK developed clinical EEHV-1A infections. Case 1 showed signs of myalgia for the duration of 24 hours before returning back to normal. EEHV-1A DNAemia was confirmed on the day of clinical signs and continued to be present for 18 days in total. Trunk shedding of the virus commenced 10 days after detection of initial DNAemia. Case 2 tested positive for EEHV-1A DNAemia in a routine blood screening sample in the absence of clinical signs. The blood viral load increased exponentially leading up to fatal clinical disease seven days after initial detection of DNAemia. Both calves were treated with 15 mg/kg FCV per rectum on detection of DNAemia and penciclovir, the FCV metabolite, could be detected in the blood at assumed therapeutic levels. The early indicators for clinical disease were a marked absolute and relative drop in white blood cells, particularly monocytes prior to the detection of viraemia. The most prognostic haematological parameter at later stages of the disease was the platelet count showing a continuous sharp decline throughout, followed by a dramatic drop at the time of death.

Conclusions

The EEHV-1A viraemic animals investigated here further highlight the ongoing threat posed by these viruses to juvenile Asian elephants. The findings call into question the efficacy of rectal FCV in clinical cases and direct towards the use of alternative anti-herpesvirus drugs and complementary treatments such as plasma infusions if no improvement in either viral load or the above-mentioned blood parameters are observed in the initial days of viraemia despite anti-herpesvirus therapy.

Herpes Simplex Virus-1 Encephalitis in Adults: Pathophysiology, Diagnosis, and Management

Herpetic infections have plagued humanity for thousands of years, but only recently have advances in antiviral medications and supportive treatments equipped physicians to combat the most severe manifestations of disease. Prompt recognition and treatment can be life-saving in the care of patients with herpes simplex-1 virus encephalitis, the most commonly identified cause of sporadic encephalitis worldwide. Clinicians should be able to recognize the clinical signs and symptoms of the infection and familiarize themselves with a rational diagnostic approach and therapeutic modalities, as early recognition and treatment are key to improving outcomes. Clinicians should also be vigilant for the development of acute complications, including cerebral edema and status epilepticus, as well as chronic complications, including the development of autoimmune encephalitis associated with antibodies to the N-methyl-D-aspartate receptor and other neuronal cell surface and synaptic epitopes. Herein, we review the pathophysiology, differential diagnosis, and clinical and radiological features of herpes simplex virus-1 encephalitis in adults, including a discussion of the most common complications and their treatment. While great progress has been made in the treatment of this life-threatening infection, a majority of patients will not return to their previous neurologic baseline, indicating the need for further research efforts aimed at improving the long-term sequelae.

Ganciclovir ophthalmic gel treatment shortens the recovery time and prevents complications in the adenoviral eye infection

The purpose of this study was to determine the effectiveness of ganciclovir ophthalmic gel (GOG) in the treatment of adenoviral eye infection (AEI) by looking at the effect of the drug on shortening recovery time, preventing transmission, reducing sequelae, and on complications such as corneal infiltrates and conjunctival pseudomembranes. 200 patients' examination records were evaluated retrospectively. Patients who were within the first 3 days of AEI were divided into two groups: Group 1 with 100 patients who used artificial tears as treatment, and Group 2 with 100 patients who used GOG plus artificial tears (GAT). All patients underwent an eye examination by the same ophthalmologist on the 1st, 5th, 10th, and 15th day after treatment. Using the examination records, variables were compared using SPSS 22.0. There was a statistically significant difference between Groups 1 and 2. Group 2 showed better and faster response to treatment. There was less transmission to the contralateral eye and environment, and less formation of corneal subepithelial infiltrate and conjunctival pseudomembrane in Group 2. Only three patients in Group 2 had corneal involvement. A comparison of each group pre-treatment and during treatment revealed improved signs and symptoms in Group 2 (p < 0.005). The study showed a trend toward more rapid improvement, less corneal and conjunctival involvement, and less transmission to the contralateral eye and environment in the GAT group. These results need to be confirmed by additional studies.

Inhibition of IKKα by BAY61-3606 Reveals IKKα-Dependent Histone H3 Phosphorylation in Human Cytomegalovirus Infected Cells

Protein kinase inhibitors can be used as tools to identify proteins and pathways required for virus replication. Using virus replication assays and western blotting we found that the widely used protein kinase inhibitor BAY61-3606 inhibits replication of human cytomegalovirus (HCMV) strain AD169 and the accumulation of HCMV immediate-early proteins in AD169 infected cells, but has no effect on replication of HCMV strain Merlin. Using in vitro kinase assays we found that BAY61-3606 is a potent inhibitor of the cellular kinase IKKα. Infection of cells treated with siRNA targeting IKKα indicated IKKα was required for efficient AD169 replication and immediate-early protein production. We hypothesized that IKKα was required for AD169 immediate-early protein production as part of the canonical NF-κB signaling pathway. However, although BAY61-3606 inhibited phosphorylation of the IKKα substrate IκBα, we found no canonical or non-canonical NF-κB signaling in AD169 infected cells. Rather, we observed that treatment of cells with BAY61-3606 or siRNA targeting IKKα decreased phosphorylation of histone H3 at serine 10 (H3S10p) in western blotting assays. Furthermore, we found treatment of cells with BAY61-3606, but not siRNA targeting IKKα, inhibited the accumulation of histone H3 acetylation (H3K9ac, H3K18ac and H3K27ac) and tri-methylation (H3K27me3 and H3K36me3) modifications. Therefore, the requirement for IKKα in HCMV replication was strain-dependent and during replication of an HCMV strain requiring IKKα, IKKα-dependent H3S10 phosphorylation was associated with efficient HCMV replication and immediate-early protein production. Plus, inhibition of HCMV replication by BAY61-3606 is associated with acetylation and tri-methylation modifications of histone H3 that do not involve IKKα.

Pharmacokinetic considerations in the use of antivirals in neonates

INTRODUCTION

Neonatal patients, because of the inability of their immune system to properly respond to microbial challenge, are highly susceptible to viral infections. Immunoglobulins, monoclonal antibody and antiviral drugs are used for prophylaxis and treatment of viral diseases in neonates. Neonates and, especially, preterm infants differ in drug absorption, distribution, metabolism and excretion from adults and older children.

AREAS COVERED

This review will evaluate deficiencies of neonatal immune responses to microbial challenge that predispose newborns to viral infections, clinical manifestations and the treatment of viral diseases in neonates. We focus on published studies describing antiviral drug pharmacokinetics in neonates and make recommendations on the dosing of these drugs, allowing achievement of maximal clinical benefits in neonates.

EXPERT OPINION

While some efforts were undertaken to study pharmacokinetics and pharmacodynamics of antiviral drugs, much more needs to be done. Current data indicate that the pharmacokinetics of antiviral drugs may vary significantly depending on gestational age, maturation processes of drug-metabolizing enzymes and renal clearance. Specifics of pharmacokinetics of antiviral drugs need to be taken into consideration when they are prescribed to neonates and infants.

Bioactive natural products with anti-herpes simplex virus properties

Objectives

In this review, we highlight and summarise the most promising extracts, fractions and pure compounds as potential anti-herpes simplex virus (HSV) agents derived from microorganisms, marine organisms, fungi, animals and plants. The role of natural products in the development of anti-HSV drugs will be discussed.

Key findings

Herpes simplex viruses (HSV-1 and -2) are common human pathogens that remain a serious threat to human health. In recent years, a great interest has been devoted to the search for integrated management of HSV infections. Acyclovir and related nucleoside analogues have been licensed for the therapy that target viral DNA polymerase. Although these drugs are currently effective against HSV infections, the intensive use of these drugs has led to the problem of drug-resistant strains. Therefore, the search for new sources to develop new antiherpetic agents has gained major priority to overcome the problem.

Summary

Natural products as potential, new anti-HSV drugs provide several advantages such as reduced side effects, less resistance, low toxicity and various mechanisms of action. This paper aims to provide an overview of natural products that possess antiviral activity against HSV.

Diagnosis and management of common gastrointestinal tract infectious diseases in ulcerative colitis and Crohn's disease patients

Management of inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, stretches beyond control of flares. Some infections of the gastrointestinal tract are more commonly seen in patients with IBD. Work from the Human Microbiome Project has been instrumental in our understanding of the interplay between the vast gut microbiota and host immune responses. Patients with IBD may be more prone to infectious complications based on their underlying inflammatory disease and variations in their microbiome. Immunosuppressant medications commonly used to treat patients with Crohn's and colitis also play a role in predisposing these patients to acquire these infections. Here, we present a detailed review of the data focusing on the most common infections of the gastrointestinal tract in patients with IBD: Clostridium difficile infections (CDI) and cytomegalovirus (CMV). We will discuss appropriate diagnostic tools and treatment options for these infections. Other less common infections will also be reviewed briefly. Studying the various infections of the gastrointestinal tract in these patients could enhance our understanding of the pathophysiology of IBD.

Clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir in children with cytomegalovirus infection

INTRODUCTION

Among infants and immunocompromised children cytomegalovirus (CMV) is associated with significant morbidity and mortality.

AREAS COVERED

This review describes the clinical pharmacokinetics and pharmacodynamics of ganciclovir and valganciclovir for the treatment and prevention of CMV infection in children.

EXPERT OPINION

A 24-h ganciclovir area under the concentration versus time curve (AUC₀₋₂₄) of 40 - 60 μg h/ml decreased the risk of CMV infection for adults undergoing CMV prophylaxis. For adults undergoing treatment for active CMV disease, a target AUC₀₋₁₂ of 40 - 60 μg h/ml has been suggested. The applicability of these targets to children remains uncertain; however, with the most sophisticated dosing regimens developed to date only 21% of patients are predicted to reach these targets. Moving forward, identification of optimal pediatric ganciclovir and valganciclovir dosing regimens may involve the use of an externally validated pediatric population pharmacokinetic model for empirical dosing, an optimal sampling strategy for collecting a minimal number of blood samples for each patient and Bayesian updating of the dosing regimen based on an individual patient's pharmacokinetic profile.

Antiviral Agents☆

Antiviral agents are drugs approved in the USA by the Food and Drug Administration (FDA) for the treatment or control of viral infections. Available antiviral agents mainly target stages in the viral life cycle. The target stages in the viral life cycle are; viral attachment to host cell, uncoating, synthesis of viral mRNA, translation of mRNA, replication of viral RNA and DNA, maturation of new viral proteins, budding, release of newly synthesized virus, and free virus in body fluids.

Two important factors that can limit the utility of antiviral drugs are toxicity and the development of resistance to the antiviral agent by the virus. In addition, host phenotypic behaviors toward antiviral drugs because of either genomic or epigenetic factors could limit the efficacy of an antiviral agent in an individual. This article summarizes the most relevant pharmacologic and clinical properties of current antiviral agents, and targets for novel antiviral agents.

Management of herpesvirus infections

Management of human herpesviruses remains a considerable clinical challenge, in part due to their ability to cause both lytic and latent disease. Infection with the Herpesviridae results in lifelong infection, which can reactivate at any time. Control of herpesviruses is by the innate and adaptive immune systems. Herpesviruses must evade the host innate immune system to establish infection. Once infected, the adaptive immune response, primarily CD8(+) T-cells, is crucial in establishing and maintaining latency. Latent herpesviruses are characterised by the presence of viral DNA in infected cells and limited or no viral replication. These characteristics provide a challenge to clinicians and those developing antiviral agents. The scope of this review is two-fold. First, to provide an overview of all antivirals used against herpesviruses, including their mechanism of action, pharmacokinetics, side effects, resistance and clinical uses. And second, to address the management of each of the eight herpesviruses both in the immunocompetent and immunocompromised host, providing evidence for clinical management and therapeutic options, which is important to the clinician engaged in the management of these infections.

Clinical significance of cytomegalovirus infection in patients with inflammatory bowel disease

Cytomegalovirus (CMV) infection is common in humans. The virus then enters a “latency phase” and can reactivate to different stimuli such as immunosuppression. The clinical significance of CMV infection in inflammatory bowel disease is different in Crohn’s disease (CD) and ulcerative colitis (UC). CMV does not interfere in the clinical course of CD. However, CMV reactivation is frequent in severe or steroid-resistant UC. It is not known whether the virus exacerbates the disease or simply appears as a bystander of a severe disease. Different methods are used to diagnose CMV colitis. Diagnosis is classically based on histopathological identification of viral-infected cells or CMV antigens in biopsied tissues using haematoxylin-eosin or immunohistochemistry, other tests on blood or tissue samples are currently being investigated. Polymerase chain reaction performed in colonic mucosa has a high sensitivity and a positive result could be associated with a worse prognosis disease; further studies are needed to determine the most appropriate strategy with positive CMV-DNA in colonic mucosa. Specific endoscopic features have not been described in active UC and CMV infection. CMV colitis is usually treated with ganciclovir for several weeks, there are different opinions about whether or not to stop immunosuppressive therapy. Other antiviral drugs may be used. Multicenter controlled studies would needed to determine which subgroup of UC patients would benefit from early antiviral treatment.

Targeted expression of herpes simplex virus thymidine kinase in adenovirus-infected cells reduces virus titers upon treatment with ganciclovir in vitro

BACKGROUND

Adenoviruses are a frequent cause of life-threatening infections in immunocompromised patients. Available therapeutics still cannot completely prevent fatal outcomes. By contrast, herpes viruses are well treatable with prodrugs such as ganciclovir (GCV), which are selectively activated in virus-infected cells by virus-encoded thymidine kinases. This effective group of prodrugs is not applicable to adenoviruses and other DNA viruses because they lack those kinases.

METHODS

To render adenoviruses amenable to GCV treatment, we generated an adenoviral vector-based delivery system for targeted expression of herpes simplex virus thymidine kinase (HSV-TK) in wild-type adenovirus 5 (wt Ad5)-infected cells. HSV-TK expression was largely restricted to wt virus-infected cells by transcription of the gene from the Ad5 E4 promoter. Its activity is dependent on the adenoviral E1A gene product which is not produced by the vector but is only provided in cells infected with wt adenovirus. The anti-adenoviral effect of HSV-TK expression and concomitant treatment with GCV was assessed in vitro in four different cell lines or primary cells.

RESULTS

E4 promoter-mediated HSV-TK background expression was sufficiently low to prevent cytotoxicity in the presence of low-levels GCV in cells not infected with wt Ad5. However, expression was several-fold increased in wt Ad5-infected cells and treatment with low levels of GCV efficiently inhibited wt Ad5 DNA replication. Genome copy numbers and output of infectious particles were reduced by up to > 99.99% and cell viability was greatly increased.

CONCLUSIONS

We extended the concept of enzyme/prodrug therapy to adenovirus infections by selectively sensitizing adenovirus-infected cells to treatment with GCV.

Diarrhea in the immunocompromised patient

Diarrhea is a common problem in patients with immunocompromising conditions. The etiologic spectrum differs from patients with diarrhea who have a normal immune system. This article reviews the most important causes of diarrhea in immunocompromised patients, ranging from infectious causes to noninfectious causes of diarrhea in the setting of HIV infection as a model for other conditions of immunosuppression. It also deals with diarrhea in specific situations, eg, after hematopoietic stem cell or solid organ transplantation, diarrhea induced by immunosuppressive drugs, and diarrhea in congenital immunodeficiency syndromes.

Development and Validation of RP-HPLC Method for the Determination of Ganciclovir in Bulk Drug and in Formulations

A simple, rapid, accurate, and precise gradient reversed-phase HPLC (RP-HPLC) method has been developed for the determination of ganciclovir (GNC) in pharmaceuticals. Chromatographic separation was carried out on inertsil ODS C18 (4.6 mm  mm, 5.0 μm) LC column using ammonium acetate buffer, sodium salt of hexane sulfonic acid as ion-pairing reagent in 1000 mL water, and acetonitrile (90 : 10) (v/v) as mobile phase at a flow rate of 1.0 mL  and with UV detection at 245 nm at column temperature (30°C). The runtime under these chromatographic conditions was 10 min. The method was linear over the range of 0.02–75 μg . The limits of detection (LOD) and quantification (LOQ) values were 4.1 and 20 ng , respectively. The method was successfully extended to study the effect on GNC upon treatment with 2 N NaOH, 2N HCl, and 5% H2O2 for 2 hrs at 80°C and upon exposure to UV (1200 K lux hrs) for 72 hrs and thermal (105°C) for 5 hrs. The proposed method was further applied to the determination of GNC in pharmaceuticals, with good percent recovery. The accuracy and the precision of the method were validated on intraday and interday basis in accordance with ICH guidelines.

The use of antiviral drugs during the neonatal period

Parenteral therapy of viral infections of the newborn and infant began with vidarabine (adenine arabinoside) for the treatment of neonatal herpes simplex virus (HSV) infections in the early 1980s. Acyclovir has become the treatment of choice for neonatal HSV infections and a variety of other herpesvirus infections. Ganciclovir is beneficial for the treatment of congenital cytomegalovirus (CMV) infections involving the central nervous system (CNS). This article reviews the use of acyclovir and ganciclovir in the treatment of neonatal HSV and congenital CMV infections. A brief summary precedes a detailed discussion of available established and alternative therapeutics.

Targeting KSHV/HHV-8 latency with COX-2 selective inhibitor nimesulide: a potential chemotherapeutic modality for primary effusion lymphoma

The significance of inflammation in KSHV biology and tumorigenesis prompted us to examine the role of COX-2 in primary effusion lymphoma (PEL), an aggressive AIDS-linked KSHV-associated non-Hodgkin's lymphoma (NHL) using nimesulide, a well-known COX-2 specific NSAID. We demonstrate that (1) nimesulide is efficacious in inducing proliferation arrest in PEL (KSHV+/EBV-; BCBL-1 and BC-3, KSHV+/EBV+; JSC-1), EBV-infected (KSHV-/EBV+; Raji) and non-infected (KSHV-/EBV-; Akata, Loukes, Ramos, BJAB) high malignancy human Burkitt's lymphoma (BL) as well as KSHV-/EBV+ lymphoblastoid (LCL) cell lines; (2) nimesulide is selectively toxic to KSHV infected endothelial cells (TIVE-LTC) compared to TIVE and primary endothelial cells (HMVEC-d); (3) nimesulide reduced KSHV latent gene expression, disrupted p53-LANA-1 protein complexes, and activated the p53/p21 tumor-suppressor pathway; (4) COX-2 inhibition down-regulated cell survival kinases (p-Akt and p-GSK-3β), an angiogenic factor (VEGF-C), PEL defining genes (syndecan-1, aquaporin-3, and vitamin-D3 receptor) and cell cycle proteins such as cyclins E/A and cdc25C; (5) nimesulide induced sustained cell death and G1 arrest in BCBL-1 cells; (6) nimesulide substantially reduced the colony forming capacity of BCBL-1 cells. Overall, our studies provide a comprehensive molecular framework linking COX-2 with PEL pathogenesis and identify the chemotherapeutic potential of nimesulide in treating PEL.