Aciclovir. A reappraisal of its antiviral activity, pharmacokinetic properties and therapeutic efficacy

Combination therapy synergism prediction for virus treatment using machine learning models

Combining different drugs synergistically is an essential aspect of developing effective treatments. Although there is a plethora of research on computational prediction for new combination therapies, there is limited to no research on combination therapies in the treatment of viral diseases. This paper proposes AI-based models for predicting novel antiviral combinations to treat virus diseases synergistically. To do this, we assembled a comprehensive dataset comprising information on viral strains, drug compounds, and their known interactions. As far as we know, this is the first dataset and learning model on combination therapy for viruses. Our proposal includes using a random forest model, an SVM model, and a deep model to train viral combination therapy. The machine learning models showed the highest performance, and the predicted values were validated by a t-test, indicating the effectiveness of the proposed methods. One of the predicted combinations of acyclovir and ribavirin has been experimentally confirmed to have a synergistic antiviral effect against herpes simplex type-1 virus, as described in the literature.

Viral replication organelles: the highly complex and programmed replication machinery

Viral infections usually induce the rearrangement of cellular cytoskeletal proteins and organelle membrane structures, thus creating independent compartments [termed replication organelles (ROs)] to facilitate viral genome replication. Within the ROs, viral replicases, including polymerases, helicases, and ligases, play functional roles during viral replication. These viral replicases are pivotal in the virus life cycle, and numerous studies have demonstrated that the viral replicases could be the potential targets for drugs development. Here, we summarize primarily the key replicases within viral ROs and emphasize the advancements of antiviral drugs targeting crucial viral replicases, providing novel insights into the future development of antiviral strategies.

Evolutionary Dynamics of Accelerated Antiviral Resistance Development in Hypermutator Herpesvirus

Antiviral therapy is constantly challenged by the emergence of resistant pathogens. At the same time, experimental approaches to understand and predict resistance are limited by long periods required for evolutionary processes. Here, we present a herpes simplex virus 1 mutant with impaired proofreading capacity and consequently elevated mutation rates. Comparing this hypermutator to parental wild type virus, we study the evolution of antiviral drug resistance in vitro. We model resistance development and elucidate underlying genetic changes against three antiviral substances. Our analyzes reveal no principle difference in the evolutionary behavior of both viruses, adaptive processes are overall similar, however significantly accelerated for the hypermutator. We conclude that hypermutator viruses are useful for modeling adaptation to antiviral therapy. They offer the benefit of expedited adaptation without introducing apparent bias and can therefore serve as an accelerator to predict natural evolution.

Viral Keratitis, Surgical Intervention in Viral Keratitis, Challenges in Diagnosis and Treatment of Viral Keratitis, HSV, HZV

Viral keratitis is a significant cause of ocular morbidity and visual impairment worldwide. In recent years, there has been a growing understanding of the pathogenesis, clinical manifestations, and diagnostic modalities for viral keratitis. The most common viral pathogens associated with this condition are adenovirus, herpes simplex (HSV), and varicella-zoster virus (VZV). However, emerging viruses such as cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Vaccinia virus can also cause keratitis. Non-surgical interventions are the mainstay of treatment for viral keratitis. Antiviral agents such as Acyclovir, Ganciclovir, and trifluridine have effectively reduced viral replication and improved clinical outcomes. Additionally, adjunctive measures such as lubrication, corticosteroids, and immunomodulatory agents have alleviated symptoms by reducing inflammation and facilitating tissue repair. Despite these conservative approaches, some cases of viral keratitis may progress to severe forms, leading to corneal scarring, thinning, or perforation. In such instances, surgical intervention becomes necessary to restore corneal integrity and visual function. This review article aims to provide an overview of the current perspectives and surgical interventions in managing viral keratitis. The choice of surgical technique depends on the extent and severity of corneal involvement. As highlighted in this article, on-going research and advancements in surgical interventions hold promise for further improving outcomes in patients with viral keratitis.

Reconstructive Methodology in the Synthesis of 2-Aminopurine

A fundamentally new synthetic approach to the synthesis of 2-aminopurine has been developed. It consists in the combination of the creation of a condensed polyazotic heterocyclic tetrazolopyrimidine structure, its transformation into triaminopyrimidine, and its subsequent cyclization into 2-aminopurine. The structure of the obtained compounds was established based on spectral characteristics, and the structure of the intermediate compound 5 was established directly by X-ray diffraction analysis.

Pharmacokinetic profile of acyclovir in a child receiving continuous kidney replacement therapy for acute liver failure

BACKGROUND

Continuous venovenous hemodiafiltration (CVVHDF) is one of the treatments of critically ill children presenting severe acute liver failure. This affliction might be induced by HSV infection requiring a treatment by acyclovir. Continuous kidney replacement therapy (CKRT) can alter its pharmacokinetics, according to its physicochemical properties and CVVHDF settings.

CASE-DIAGNOSIS/TREATMENT

The patient was a 21-month-old female presenting liver failure with hyperammonemia treated by acyclovir with presumed HSV infection. CKRT was initiated on day 1 with substantial replacement and dialysate flow rates (respectively 75 and 220 mL/kg/h). Acyclovir was intravenously administered every 8 h with a 1-h infusion of 500 mg/m2. Plasma and effluent concentrations were measured by liquid chromatography-tandem mass spectrometry assay to estimate the area under a curve (AUC) and CKRT clearance by 2 methods (one based on pre- and post-filter concentrations and the other one on dialysate flow rates). Clearance was estimated between 19.2 and 26.3 mL/min with the first method and between 27.6 and 44.3 mL/min with the second one. Concentrations were highly above the therapeutic index (peak concentration was measured at 28 mg/L), but AUC was appropriate.

CONCLUSIONS

This case describes acyclovir pharmacokinetics during CKRT in a pediatric patient treated by acyclovir. The patient was treated with adapted exposure with the usual dosing, but lower dosing should be investigated with complementary studies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02539407.

The Impact of Antiviral Resistance on Herpetic Keratitis

ABSTRACT

Herpes simplex keratitis resistance to antiviral treatment presents a growing concern. The herpes simplex virus has many different mechanisms of resistance to antiviral treatment, which have been well described. Resistance to acyclovir occurs because of mutations in the viral thymidylate kinase and DNA polymerase that decrease this enzyme's affinity for its substrate. This article discusses factors that explain the prevalence of this resistance, the ability for recurrences in immunocompromised populations, current treatments for acyclovir-resistant herpes simplex keratitis, and novel therapies for this growing concern.

Current Development of Chemical Penetration Enhancers for Transdermal Insulin Delivery

The use of the transdermal delivery system has recently gained ample recognition due to the ability to deliver drug molecules across the skin membrane, serving as an alternative to conventional oral or injectable routes. Subcutaneous insulin injection is the mainstay treatment for diabetes mellitus which often leads to non-compliance among patients, especially in younger patients. Apart from its invasiveness, the long-term consequences of insulin injection cause the development of physical trauma, which includes lipohypertrophy at the site of administration, scarring, infection, and sometimes nerve damage. Hence, there is a quest for a better alternative to drug delivery that is non-invasive and easily adaptable. One of the potential solutions is the transdermal delivery method. However, the stratum corneum (the top layer of skin) is the greatest barrier in transporting large molecules like insulin. Therefore, various chemical enhancers have been proposed to promote stratum corneum permeability, or they are designed to increase the permeability of the full epidermis, such as the use of ionic liquid, peptides, chemical pre-treatment as well as packaging insulin with carriers or nanoparticles. In this review, the recent progress in the development of chemical enhancers for transdermal insulin delivery is discussed along with the possible mechanistic of action and the potential outlook on the proposed permeation approaches in comparison to other therapeutical drugs

Optimizing Antiviral Dosing for HSV and CMV Treatment in Immunocompromised Patients

Herpes simplex virus (HSV) and cytomegalovirus (CMV) are DNA viruses that are common among humans. Severely immunocompromised patients are at increased risk of developing HSV or CMV disease due to a weakened immune system. Antiviral therapy can be challenging because these drugs have a narrow therapeutic window and show significant pharmacokinetic variability. Above that, immunocompromised patients have various comorbidities like impaired renal function and are exposed to polypharmacy. This scoping review discusses the current pharmacokinetic (PK) and pharmacodynamic (PD) knowledge of antiviral drugs for HSV and CMV treatment in immunocompromised patients. HSV and CMV treatment guidelines are discussed, and multiple treatment interventions are proposed: early detection of drug resistance; optimization of dose to target concentration by therapeutic drug monitoring (TDM) of nucleoside analogs; the introduction of new antiviral drugs; alternation between compounds with different toxicity profiles; and combinations of synergistic antiviral drugs. This research will also serve as guidance for future research, which should focus on prospective evaluation of the benefit of each of these interventions in randomized controlled trials.

Real-World Data on Cutaneous Recurrences Following Neonatal Herpes Simplex Virus Disease

Though primarily used to improve neurodevelopmental outcomes, suppressive oral acyclovir therapy following neonatal herpes simplex virus disease also decreases cutaneous recurrences. Skin recurrences can still occur, however, and understanding their frequency is helpful in managing patients with this rare disease.

Effect of Hydrophilic Polymers on the Release Rate and Pharmacokinetics of Acyclovir Tablets Obtained by Wet Granulation: In Vitro and In Vivo Assays

This study aims to evaluate the feasibility of producing acyclovir-containing modified release matrix tablets by a wet granulation method based on the type and concentration of two pharmaceutical-grade hydrophilic matrix polymers (i.e., hydroxypropyl methylcellulose (HPMC), carbomers, and their combinations) commonly used in biomedical applications. The mechanical properties of the tablets and in vitro and in vivo performance were studied. The physicochemical properties of the raw materials and corresponding physical mixtures were characterized by differential scanning calorimetry, showing that the hydrophilic polymers did not influence the physicochemical properties of the drug. The wet granulation process improved the flow and compression properties of the obtained granules. This method enabled the preparation of the matrix tablets of acyclovir with appropriate mechanical properties concerning hardness and friability. The drug release kinetics was governed by the type and concentration of the hydrophilic polymers composing the matrices. The study has proven that HPMC-composed tablets were superior in modified drug release properties compared to carbomer- and HPMC/carbomer-based tablets. Mathematical analysis of the release profiles, determined in a medium adjusted to pH 1.2 followed by pH 7.4, revealed that the drug released from the hydrophilic tablets followed non-Fickian first-order kinetics. An optimal HPMC-based formulation submitted to accelerated stability studies (40 °C, 75% RH) was stable for three months. A complete cross-over bioavailability study of the selected acyclovir-loaded sustained release tablets and marketed immediate-release tablets were compared in six healthy male volunteers. The extent of drug absorption from the sustained release tablets was significantly greater than that from immediate-release pills, which may improve the drug's antiviral properties attributed to the lower elimination rate and enhanced acyclovir half-life.

Nanomaterials for Photocatalytic Degradations of Analgesic, Mucolytic and Anti-Biotic/Viral/Inflammatory Drugs Widely Used in Controlling SARS-CoV-2

The COVID-19 pandemic has been transformed into one of the main worldwide challenges, in recent years. For controlling symptoms that are caused by this disease (e.g., chills or fever, shortness of breath and/or difficulty in breathing, cough, sore throat, fatigue, headache, muscle aches, the new loss of tastes and/or smells, congestion or runny nose, nausea, vomiting and/or diarrhea), lots of medicines including analgesics, mucolytics, and anti-biotic/viral/inflammatory drugs have been frequently prescribed. As these medicines finally contaminate terrestrial and aquatic habitats by entering surface waterways through pharmaceutical production and excreting trace amounts of waste after human usage, they have negative impacts on wildlife’s health and ecosystem. Residual drugs in water have the potential to harm aquatic creatures and disrupt their food chain as well as the breeding cycle. Therefore, proper degradation of these broadly used medicines is highly crucial. In this work, the use of nanomaterials applicable in photocatalytic degradations of analgesics (e.g., acetaminophen, aspirin, ibuprofen, and naproxen), mucolytics (e.g., ambroxol), antibiotics (e.g., azithromycin and quinolones including hydroxychloroquine and chloroquine phosphate), anti-inflammatory glucocorticoids (e.g., dexamethasone and cortisone acetate), antihistamines (e.g., diphenhydramine), H2 blockers (e.g., famotidine), anthelmintics (e.g., praziquantel), and finally antivirals (e.g., ivermectin, acyclovir, lopinavir/ritonavir, favipiravir, nitazoxanide, and remdesivir) which widely used in controlling/treating the coronavirus have been reviewed and discussed.

Primary Varicella or Herpes Zoster? An Educational Case Report From the Primary Care Clinic

Varicella-zoster virus is a pathogenic virus that can present itself as a primary infection or secondary infection, also known as herpes zoster. Recently, there has been a re-emergence of this vaccine-preventable disease due to gaps in vaccination. Primary varicella in immunocompetent adults is highly uncommon, and it could result in severe complications within this population. Given this delicate scenario, family physicians should be well trained to recognize the characteristic cutaneous lesions of varicella and dictate adequate management for these patients to obtain the best possible outcome and prevent life-threatening complications.

We present the case of a 43-year-old immunocompetent woman with the onset of a generalized pruritic dermatosis characterized primarily by the presence of macules, vesicles, and crusts. The patients' lesions were compatible with primary varicella, and serological studies confirmed the diagnosis. Given the absence of acute complications in this individual, supportive treatment and close follow-up were the therapeutic modalities. This article focuses on the educational discussion of the primary differential diagnosis, evaluation for possible complications, and management of this uncommon clinical scenario. We also reinforce the importance of immunization in preventing re-emergent diseases as a critical element within primary care management.

Comparative efficacy of early Covid-19 monoclonal antibody therapies: a retrospective analysis

Background

Bamlanivimab and casirivimab/imdevimab are monoclonal antibody (mAb) treatments used for mild to moderate coronavirus disease 2019 (COVID-19) in high-risk patients. To date, there are few data summarizing real-world evidence comparing the 2 mAbs. Additionally, there are insufficient data to guide administration timing relative to symptom onset. The purpose of this study was to evaluate 30-day failure rates for each agent and to identify the relationship between symptom onset and efficacy.

Methods

We performed a retrospective cohort study of a 6-month period at a large community medical center. Consecutive outpatients diagnosed with COVID-19 disease by nasopharyngeal (NP) polymerase chain reaction (PCR) testing received either bamlanivimab 700 mg or casirivimab/imdevimab 1200 mg/1200 mg. Each patient was followed for a total of 30 days. Three independent, blinded physicians performed adjudication for revisit reasons. The primary outcome was therapy-related failure, defined as COVID-19-related hospital admission within 30 days of infusion. Multivariable logistic regression was performed to adjust for confounders that may have influenced hospital admission in either group.

Results

During the period from November 2020 to May 2021, 183 patients were treated with bamlanivimab and 270 with casirivimab/imdevimab. The mean age was ~67 years and body mass index 30 kg/m². Thirty-day admission for therapy-related failure rates were 4.8% and 13.7% for casirivimab/imdevimab and bamlanivimab, respectively (P = .001). No significant differences were found between early (<3 days of symptom onset) and late administration of either mAb.

Conclusions

There was a higher failure rate with bamlanivimab vs casirivimab/imdevimab. No difference in efficacy was found between early vs late administration of either mAb.

Effects of synthesis conditions and release medium pH on release properties of acyclovir - mercaptopropyl modified silica composite

OBJECTIVE

The purpose of the present study was to evaluate the prospect of use of mercaptopropyl modified silica as a platform for development of new oral formulation of antiviral drug acyclovir (ACV) which is able to control release of the drug irrespective of release medium pH.

METHODS

The composites of ACV with mercaptopropyl modified silica were synthesized using sol-gel technology under different conditions (synthesis pH, drug loading). The composites were characterized using scanning electron microscopy, dynamic light scattering and differential scanning calorimetry methods. The effects of the synthesis conditions on physicochemical properties of the prepared composites and their release properties were studied.

RESULTS

The sol-gel synthesis conditions and release medium pH influence significantly release properties of the composites. The influence was explained by contributions of different factors, such as the drug-silica interactions in the composites, structure of the silica matrix and its stability in release media, hydrophobic nature of ACV, its pH-dependent solubility. It was found that all the synthesized composites followed the zero-order kinetics which is controlled by anomalous diffusion.

CONCLUSION

The studies showed that the composites exhibited controlled release of ACV up to 80 h.However, the release properties of the drug depend significantly on pH of release medium, i.e. the release properties (the release rate, the amount of released ACV) will change during transition of the composites through various segments of GIT. Therefore, the synthesized composites are not a promising basis for development of new oral dosage form of ACV.

Pharmacokinetics and analytical determination of acyclovir in Asian elephant calves (Elephas maximus)

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Pharmacokinetic and bioavailability data of acyclovir following intravenous and oral administration are reported for Asian elephant calves.

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Data represent the first comprehensive LC-MS/MS analysis of plasma acyclovir concentrations after i.v. and oral administration in elephants.

A therapeutic regimen that includes antiviral drugs is critical for the survival of Asian elephant (Elephas maximus) calves infected with elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD), with acyclovir showing considerable promise. The purpose of this study was to determine the pharmacokinetics and bioavailability of acyclovir following intravenous (IV) and oral (PO) administration in Asian elephants. A single dose of acyclovir (15 mg/kg, IV or 45 mg/kg, PO) was administered to four healthy elephant calves, with a minimum 2-week washout period between treatments. Serial plasma samples were collected after each injection for acyclovir analysis using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique. Maximum plasma acyclovir concentrations were 27.02 ± 6.79 µg/mL at 0.94 ± 0.31 h after IV administration, and 1.45 ± 0.20 µg/mL at 3.00 ± 0.70 h after PO administration. The half-life of the elimination phase (T_1/2) was 5.84 ± 0.74 and 8.74 ± 2.47 h after IV and PO administration, respectively. After IV administration, acyclovir concentrations were higher than the half-maximal inhibitory concentration (IC₅₀) of those found for herpes simplex virus (HSV) 1 and 2 in humans, and equid alpha herpesvirus-1 (EHV-1) for at least 12 h. By contrast, the bioavailability of oral administration was low, only 6.03 ± 0.87%, so higher doses by that route likely are needed to be effective. Due to the high concentration of plasma acyclovir after IV administration, the dose may need to be adjusted to prevent any negative side effects.

The Valproic Acid Derivative Valpromide Inhibits Pseudorabies Virus Infection in Swine Epithelial and Mouse Neuroblastoma Cell Lines

Pseudorabies virus (PRV) infection of swine can produce Aujeszky’s disease, which causes neurological, respiratory, and reproductive symptoms, leading to significant economic losses in the swine industry. Although humans are not the natural hosts of PRV, cases of human encephalitis and endophthalmitis caused by PRV infection have been reported between animals and workers. Currently, a lack of specific treatments and the emergence of new PRV strains against which existing vaccines do not protect makes the search for effective antiviral drugs essential. As an alternative to traditional nucleoside analogues such as acyclovir (ACV), we studied the antiviral effect of valpromide (VPD), a compound derived from valproic acid, against PRV infection in the PK15 swine cell line and the neuroblastoma cell line Neuro-2a. First, the cytotoxicity of ACV and VPD in cells was compared, demonstrating that neither compound was cytotoxic at a specific concentration range after 24 h exposure. Furthermore, the lack of direct virucidal effect of VPD outside of an infected cell environment was demonstrated. Finally, VPD was shown to have an antiviral effect on the viral production of two strains of pseudorabies virus (wild type NIA-3 and recombinant PRV-XGF) at the concentrations ranging from 0.5 to 1.5 mM, suggesting that VPD could be a suitable alternative to nucleoside analogues as an antiherpetic drug against Aujeszky’s disease.

DNA polymerases of herpesviruses and their inhibitors

Human herpesviruses are large double-stranded DNA viruses belonging to the Herpesviridae family. The main characteristics of these viruses are their ability to establish a lifelong latency into the host with a potential to reactivate periodically. Primary infections and reactivations with herpesviruses are responsible for a large spectrum of diseases and may result in severe complications in immunocompromised patients. The viral DNA polymerase is a key enzyme in the replicative cycle of herpesviruses, and the target of most antiviral agents (i.e., nucleoside, nucleotide and pyrophosphate analogs). However, long-term prophylaxis and treatment with these antivirals may lead to the emergence of drug-resistant isolates harboring mutations in genes encoding viral enzymes that phosphorylate drugs (nucleoside analogs) and/or DNA polymerases, with potential cross-resistance between the different analogs. Drug resistance mutations mainly arise in conserved regions of the polymerase and exonuclease functional domains of these enzymes. In the polymerase domain, mutations associated with resistance to nucleoside/nucleotide analogs may directly or indirectly affect drug binding or incorporation into the primer strand, or increase the rate of extension of DNA to overcome chain termination. In the exonuclease domain, mutations conferring resistance to nucleoside/nucleotide analogs may reduce the rate of excision of incorporated drug, or continue DNA elongation after drug incorporation without excision. Mutations associated with resistance to pyrophosphate analogs may alter drug binding or the conformational changes of the polymerase domain required for an efficient activity of the enzyme. Novel herpesvirus inhibitors with a potent antiviral activity against drug-resistant isolates are thus needed urgently.

Segmental zoster paresis as a cause for persistent fever in an immunocompromised patient

Herpes zoster reactivation is a frequently encountered condition that can result in several uncommon complications. This case report highlights one such frequently overlooked complication, segmental zoster paresis. We discuss a case of prolonged fever and lower limb weakness in an immunocompromised patient with breast cancer on active chemotherapy after resolution of a herpetiform rash in the L2, L3 and L4 dermatomes. Early investigation with lumbar puncture, looking for cerebrospinal fluid pleocytosis, varicella zoster virus detection by PCR or molecular testing and immunoglobulins against varicella zoster virus, should be undertaken to support the diagnosis. Nerve conduction studies, electromyography and MRI of the spine can sometimes help with neurolocalisation. Intravenous acyclovir and a tapering course of steroids can help with resolution of symptoms. The variegate presentation can make diagnosis challenging. Awareness and a high index of suspicion can prevent delays in diagnosis and treatment and improve patient outcomes.

Identification of Potential Drug Targets of Broad-Spectrum Inhibitors with a Michael Acceptor Moiety Using Shotgun Proteomics

The Michael addition reaction is a spontaneous and quick chemical reaction that is widely applied in various fields. This reaction is performed by conjugating an addition of nucleophiles with α, β-unsaturated carbonyl compounds, resulting in the bond formation of C-N, C-S, C-O, and so on. In the development of molecular materials, the Michael addition is not only used to synthesize chemical compounds but is also involved in the mechanism of drug action. Several covalent drugs that bond via Michael addition are regarded as anticarcinogens and anti-inflammatory drugs. Although drug development is mainly focused on pharmaceutical drug discovery, target-based discovery can provide a different perspective for drug usage. However, considerable time and labor are required to define a molecular target through molecular biological experiments. In this review, we systematically examine the chemical structures of current FDA-approved antiviral drugs for potential Michael addition moieties with α, β-unsaturated carbonyl groups, which may exert an unidentified broad-spectrum inhibitory mechanism to target viral or host factors. We thus propose that profiling the targets of antiviral agents, such as Michael addition products, can be achieved by employing a high-throughput LC-MS approach to comprehensively analyze the interaction between drugs and targets, and the subsequent drug responses in the cellular environment to facilitate drug repurposing and/or identify potential adverse effects, with a particular emphasis on the pros and cons of this shotgun proteomic approach.

The antiviral activity of kaempferol against pseudorabies virus in mice

Background

Pseudorabies virus (PRV), a member of the Alphaherpesviruses, is one of the most important pathogens that harm the global pig industry. Accumulated evidence indicated that PRV could infect humans under certain circumstances, inducing severe clinical symptoms such as acute human encephalitis. Currently, there are no antiviral drugs to treat PRV infections, and vaccines available only for swine could not provide full protection. Thus, new control measures are urgently needed.

Results

In the present study, kaempferol exhibited anti-PRV activity in mice through improving survival rate by 22.22 %, which was higher than acyclovir (Positive control) with the survival rate of 16.67 % at 6 days post infection (dpi); meanwhile, the survival rate was 0 % at 6 dpi in the infected-untreated group. Kaempferol could inhibit the virus replication in the brain, lung, kidney, heart and spleen, especially the viral gene copies were reduced by over 700-fold in the brain, which was further confirmed by immunohistochemical examination. The pathogenic changes induced by PRV infection in these organs were also alleviated. The transcription of the only immediate-early gene IE180 in the brain was significantly inhibited by kaempferol, leading to the decreased transcriptional levels of the early genes (EPO and TK). The expression of latency-associated transcript (LAT) was also inhibited in the brain, which suggested that kaempferol could inhibit PRV latency. Kaempferol-treatment could induce higher levels of IL-1β, IL-4, IL-6, TNF-α and IFN-γ in the serum at 3 dpi which were then declined to normal levels at 5 dpi.

Conclusions

These results suggested that kaempferol was expected to be a new alternative control measure for PRV infection.

Synthesis of C6-Substituted Purine Nucleoside Analogues via Late-Stage Photoredox/Nickel Dual Catalytic Cross-Coupling

Nucleoside analogues have been and continue to be extremely important compounds in drug discovery. Despite the significant effort dedicated to their synthesis, medicinal chemistry campaigns around these structures are often hampered by synthetic challenges. We describe a strategy for the functionalization of purine nucleosides via photoredox and nickel-catalyzed sp²-sp³ cross-coupling. The conditions described herein allow for coupling of unprotected nucleosides with readily available alkyl bromides, providing opportunities for their application to parallel medicinal chemistry.

Alkoxylalkyl Esters of Nucleotide Analogs Inhibit Polyomavirus DNA Replication and Large T Antigen Activities

Polyomavirus infections occur commonly in humans and are normally nonfatal. However, in immunocompromised individuals, they are intractable and frequently fatal. Due to a lack of approved drugs to treat polyomavirus infections, cidofovir, a phosphonate nucleotide analog approved to treat cytomegalovirus infections, has been repurposed as an antipolyomavirus agent. Cidofovir has been modified in various ways to improve its efficacies as a broad-spectrum antiviral agent. However, the actual mechanisms and targets of cidofovir and its modified derivatives as antipolyomavirus agents are still under research. Here, polyomavirus large tumor antigen (Tag) activities were identified as the viral target of cidofovir derivatives. The alkoxyalkyl ester derivatives of cidofovir efficiently inhibit polyomavirus DNA replication in cell-free human extracts and a viral in vitro replication system utilizing only purified proteins. We present evidence that DNA helicase and DNA binding activities of polyomavirus Tags are diminished in the presence of low concentrations of alkoxyalkyl ester derivatives of cidofovir, suggesting that the inhibition of viral DNA replication is at least in part mediated by inhibiting single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) binding activities of Tags. These findings show that the alkoxyalkyl ester derivatives of cidofovir are effective in vitro without undergoing further conversions, and we conclude that the inhibitory mechanisms of nucleotide analog-based drugs are more complex than previously believed.

Biocatalytic routes to anti-viral agents and their synthetic intermediates

An assessment of biocatalytic strategies for the synthesis of anti-viral agents, offering guidelines for the development of sustainable production methods for a future COVID-19 remedy.

Antiviral Drugs Against Herpesviruses

The discovery of the nucleoside analogue, acyclovir, represented a milestone in the management of infections caused by herpes simplex virus and varicella-zoster virus. Ganciclovir, another nucleoside analogue, was then used for the management of systemic and organ-specific human cytomegalovirus diseases. The pyrophosphate analogue, foscarnet, and the nucleotide analogue, cidofovir, have been approved subsequently and constitute the second-line antiviral drugs. However, the viral DNA polymerase is the ultimate target of all these antiviral agents with a possible emergence of cross-resistance between these drugs. Recently, letermovir that targets the viral terminase complex was approved for the prophylaxis of human cytomegalovirus infections in hematopoietic stem cell transplant recipients. Other viral targets such as the protein kinase and the helicase-primase complex are also evaluated for the development of novel potent inhibitors against herpesviruses.

Acyclovir inhibits channel catfish virus replication and protects channel catfish ovary cells from apoptosis

The channel catfish virus (CCV) can cause lethal hemorrhagic infection in channel catfish, resulting in significant economic losses in the fish industry. Effective drugs for the virus are still lacking. Acyclovir is known as a potent antiviral agent against human herpes viruses and some animal DNA viruses. The present study was undertaken to explore the antiviral response and mechanism of acyclovir against CCV in channel catfish ovary (CCO) cells. Acyclovir was able to significantly inhibit the expression of viral genes related to CCV viral DNA synthesis and suppress viral replication at a safe concentration. Furthermore, acyclovir blocked the cytopathic effects and apoptosis induced by CCV, thereby maintaining the normal cellular morphological structure, as shown by the protection of CCO cells from the formation of apoptotic bodies or nuclear fragmentation. Moreover, reverse transcript quantitative polymerase chain reaction (RT-qPCR) demonstrated that acyclovir suppressed the expression of caspase 3, caspase 8 and caspase 9, while there was no significant impact on the expression of the apoptosis-inhibiting gene bcl-2 in CCV-infected cells. In addition, acyclovir did not promote the expression of immune-related genes such as MyD88, Mx1, IRF3, IRF7, IFN-I, NF-kB and IL-1β, suggesting that the antiviral activity of acyclovir to CCV infection is not achieved by facilitating the expression of immune-related genes in CCO cells. Taken together, the results from this study suggest that acyclovir could effectively regulate CCV-induced infection, and thus is a promising therapeutic agent against CCV. Our results will aid our understanding of the pharmacological mechanisms of antiviral agents.

An updated and comprehensive review of the antiviral potential of essential oils and their chemical constituents with special focus on their mechanism of action against various influenza and coronaviruses

Essential oils and their chemical constituents have been reported with well documented antimicrobial effects against a range of bacterial, fungal and viral pathogens. By definition, essential oils are a complex mixture of volatile organic compounds which are synthesized naturally in different parts of the plant as part of plants secondary metabolism. The chemical composition of the essential oils is dominated by the presence of a range of compounds including phenolics, terpenoids, aldehydes, ketones, ethers, epoxides and many others inferring that essential oils must be effective against a wide range of pathogens. This review article mainly focuses on the antiviral potential of essential oils and their chemical constituents especially against influenza and coronaviruses. Essential oils have been screened against several pathogenic viruses, including influenza and other respiratory viral infections. The essential oils of cinnamon, bergamot, lemongrass, thyme, lavender have been reported to exert potent antiviral effects against influenza type A virus. The essential oil of Citrus reshni leaves has been shown to be effective against H5N1 virus. The essential oil of Lippia species at a concentration of 11.1 μg/mL has been shown to induce 100% inhibition of yellow fever virus in Vero cells. Essential oils and oleoresins have been shown through in vitro and in vivo experiments to induce antiviral effects against Coronavirus infectious bronchitis virus. A study reported 221 phytochemical compounds and essential oils to be effective against severe acute respiratory syndrome associated coronavirus (SARS-CoV) using a cell-based assay measuring SARS-CoV-induced cytopathogenic effect on Vero E6 cells. The main mechanism of antiviral effects of essential oils has been found to cause capsid disintegration and viral expansion which prevents the virus to infect host cells by adsorption via the capsid. Essential oils also inhibit hemagglutinin (an important membrane protein of various viruses) of certain viruses; this membrane protein allows the virus to enter the host cell. Many essential oils and their components could inhibit the late stages of viral life cycle by targeting the redox signalling pathway. Essential oils of Thymus vulgaris, cymbopogon citratus and Rosmarinus officinalis have been found to destabilize the Tat/TAR-RNA complex of HIV-1 virus, this complex being essential for HIV-1 replication. Being lipophilic in nature, essential oils can penetrate viral membranes easily leading to membrane disintegration. The current comprehensive review will facilitate researchers to find chemical entities from plant sources as possible inhibitory agents against various viruses.

Modern Management of Facial Nerve Disorders

Facial paralysis is a devastating condition, encompassing a spectrum of disorders, with resultant psychosocial, functional, and aesthetic sequelae. With this in mind, an individualized treatment approach based on the cause, pattern, and duration of palsy is necessary. Treatment options include pharmacologic agents, corneal protective interventions, physical therapy, and surgical procedures. The use of steroids and antivirals in the setting of idiopathic facial paralysis or virus-associated facial paralysis is well supported. Despite the diversity of surgical interventions described, there is a lack of consensus regarding optimal treatment. This article provides an overview of the current management of facial paralysis. Medical, surgical, and physical treatment options are discussed with a review of the relevant literature.

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.

MicroRNA Biomarkers for Infectious Diseases: From Basic Research to Biosensing

In the pursuit of improved diagnostic tests for infectious diseases, several classes of molecules have been scrutinized as prospective biomarkers. Small (18–22 nucleotide), non-coding RNA transcripts called microRNAs (miRNAs) have emerged as promising candidates with extensive diagnostic potential, due to their role in numerous diseases, previously established methods for quantitation and their stability within biofluids. Despite efforts to identify, characterize and apply miRNA signatures as diagnostic markers in a range of non-infectious diseases, their application in infectious disease has advanced relatively slowly. Here, we outline the benefits that miRNA biomarkers offer to the diagnosis, management, and treatment of infectious diseases. Investigation of these novel biomarkers could advance the use of personalized medicine in infectious disease treatment, which raises important considerations for validating their use as diagnostic or prognostic markers. Finally, we discuss new and emerging miRNA detection platforms, with a focus on rapid, point-of-care testing, to evaluate the benefits and obstacles of miRNA biomarkers for infectious disease.

Polypseudorotaxanes of Pluronic® F127 with Combinations of α- and β-Cyclodextrins for Topical Formulation of Acyclovir

Acyclovir (ACV) is one of the most used antiviral drugs for the treatment of herpes simplex virus infections and other relevant mucosal infections caused by viruses. Nevertheless, the low water solubility of ACV limits both its bioavailability and antiviral performance. The combination of block copolymer micelles and cyclodextrins (CDs) may result in polypseudorotaxanes with tunable drug solubilizing and gelling properties. However, the simultaneous addition of various CDs has barely been investigated yet. The aim of this work was to design and characterize ternary combinations of Pluronic® F127 (PF127), αCD and βCD in terms of polypseudorotaxane formation, rheological behavior, and ACV solubilization ability and controlled release. The formation of polypseudorotaxanes between PF127 and the CDs was confirmed by FT-IR spectroscopy, X-ray diffraction, and NMR spectroscopy. The effects of αCD/βCD concentration range (0–7% w/w) on copolymer (6.5% w/w) gel features were evaluated at 20 and 37 °C by rheological studies, resulting in changes of the copolymer gelling properties. PF127 with αCD/βCD improved the solubilization of ACV, maintaining the biocompatibility (hen’s egg test on the chorio-allantoic membrane). In addition, the gels were able to sustain acyclovir delivery. The formulation prepared with similar proportions of αCD and βCD provided a slower and more constant release. The results obtained suggest that the combination of Pluronic with αCD/βCD mixtures can be a valuable approach to tune the rheological features and drug release profiles from these supramolecular gels.

Antiviral Approaches for the Treatment of Herpes Simplex Virus Infections in Newborn Infants

Herpes simplex virus (HSV) infections in newborns are associated with severe disease and death. Trials conducted by the Collaborative Antiviral Study Group have established the standard of care for the treatment of neonatal HSV disease with marked improvements in morbidity and mortality. We review the studies that have contributed to our understanding of the epidemiology and clinical course of neonatal HSV disease and discuss the landmark trials that have resulted in safe and effective treatment together with improved diagnostics. Although significant advances have been made, neonatal HSV disease continues to have an unacceptably high mortality rate with significant sequelae in survivors. Further research is urgently needed for prevention.

Recent advances in the asymmetric synthesis of pharmacology-relevant nitrogen heterocycles via stereoselective aza-Michael reactions

In this review, recent applications of a stereoselective aza-Michael reaction for asymmetric synthesis of naturally occurring N-containing heterocyclic scaffolds and their usefulness to pharmacology are summarized.

Central nervous system varicella zoster vasculopathy in an immunocompromised patient

Central nervous system (CNS) vasculopathy associated with Varicella Zoster Virus (VZV) infection, usually manifesting as stroke due to ischemic lesions by involvement of small arteries, is frequently misdiagnosed. Immunocompromised patients have a particularly higher risk of severe disease and also CNS involvement during or following VZV presentations. We report a case of an 84-year-old man, with myelodysplastic syndrome, who presented with herpes zoster ophthalmicus complicated with left periocular cellulitis and an abnormal neurological exam. Intravenous treatment with acyclovir and amoxicillin/clavulanic acid was began. VZV DNA was detected in the cerebrospinal fluid (CSF) and brain magnetic resonance imaging revealed three acute ischemic lesions in the left frontal and both cerebellar lobes. A VZV CNS multifocal vasculopathy was diagnosed and treatment with intravenous acyclovir continued for 21 days.

Immunocompromised patients with VZV infection can have a more severe course of disease with disseminated involvement and multifocal vasculopathy. In these patients the CSF detection of anti-VZV IgG as well as VZV DNA can be helpful in the diagnosis of CNS VZV vasculopathy. The antiviral treatment can improve the outcome and should be adjusted taking in consideration the degree of immunosuppression. This clinical case and review of the literature highlights the challenges in the diagnosis and management of VZV CNS vasculopathy in immunocompromised patients.

Medical Management of Acute Facial Paralysis

Acute facial paralysis (FP) describes acute onset of partial or complete weakness of the facial muscles innervated by the facial nerve. Acute FP occurs within a few hours to days. The differential diagnosis is broad; however, the most common cause is viral-associated Bell Palsy. A comprehensive history and physical examination are essential in arriving at a diagnosis. Medical treatment for acute FP depends on the specific diagnosis; however, corticosteroids and antiviral medications are the cornerstone of therapy. Lack of recovery after 4 months should prompt further diagnostic workup.

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.