Management of oral herpes simplex virus infections: The problem of resistance. A narrative review

Tackling cutaneous herpes simplex virus disease with topical immunomodulators-a call to action

SUMMARYAntivirals play important roles in restricting viral diseases. Nevertheless, they act on a relatively limited number of viruses and occasionally display partial effectiveness in some tissues or against escape variants. Although vaccination remains the most cost-effective approach for preventing microbial diseases, developing prophylactic or therapeutic solutions for pathogens, such as herpes simplex viruses (HSVs), that effectively reduce their clinical manifestations in the skin has proven exceptionally challenging despite extensive research. Alternatively, a less explored approach for tackling HSV skin infection involves using topical immunomodulatory molecules to potentiate the host's innate antiviral immune responses. When applied directly to herpetic skin lesions where viral antigen is present, this strategy has the potential to elicit virus-specific adaptive immunity. Based on currently available data, we foresee substantial potential for this approach in addressing HSV skin infections, along with additional prospects to advance understanding of skin biology and apply relevant new findings to other dermatological conditions. However, due to the limited number of case studies evaluating this method and its safety profile, particularly in immunocompromised individuals and pregnant women, further research is crucial, especially to assess the effects of immunomodulators in these vulnerable populations. Here, we revisit and discuss the use of immunomodulatory molecules for potentiating the host immune response against HSV skin infection and call for action for increased research and clinical trials regarding the possible benefits of this latter strategy for treating HSV cutaneous disease and recurrences. We also revisit and discuss antivirals and vaccine candidates against HSVs.

Refractory and Resistant Herpes Simplex Virus Mucocutaneous Infections in Immunocompromised Patients: Literature Review and Proposed Definitions for Use in Clinical Trials

Herpes simplex virus (HSV) infection is one of the most prevalent viral infections worldwide. In general, host immunity is sufficient to clear viral shedding and recurrences, although it is insufficient to prevent subsequent virologic reactivations. In immunocompromised patients, prolonged and difficult-to-treat HSV infections may develop. The diagnosis of refractory HSV infection is based on the lack of clinical response to nucleoside analogs. Antiviral resistance is confirmed via genotypic and/or phenotypic testing. To provide consensus definitions of refractory and/or resistant (R/R) HSV mucocutaneous infections for clinical trial use, the HSV Resistance Working Group of the Transplant Associated Viral Infections Forum, which includes international clinicians, scientists, industry representatives, and regulatory officials, conducted a literature review of previously published data related to R/R HSV infections in immunocompromised patients. We propose definitions of R/R HSV mucocutaneous infections, which will be subject to re-evaluation and revision based on forthcoming data and future studies.

Debulking influenza and herpes simplex virus strains by a wide-spectrum anti-viral protein formulated in clinical grade chewing gum

Lack of Herpes Simplex Virus (HSV) vaccine, low vaccination rates of Influenza viruses, waning immunity and viral transmission after vaccination underscore the need to reduce viral loads at their transmission sites. Oral virus transmission is several orders of magnitude higher than nasal transmission. Therefore, in this study, we evaluated neutralization of viruses using a natural viral trap protein (FRIL) formulated in clinical-grade chewing gum. FRIL is highly stable in the lablab bean powder (683 days) and in chewing gum (790 days), and fully functional (794 days) when stored at ambient temperature. They passed the bioburden test with no aerobic bacteria, yeasts/molds, with minimal moisture content (1.28-5.9%). Bean gum extracts trapped HSV-1/HSV-2 75-94% in a dose-dependent manner through virus self-aggregation. Mastication simulator released >50% release of FRIL within 15 min of chewing the bean gum. In plaque reduction assays, >95% neutralization of H1N1 and H3N2 required ∼40 mg/mL, HSV-1 160 mg/mL, and HSV-2 74 mg/mL of bean gum for 1,000 copies/mL virus particles. Therefore, a 2000 mg bean gum tablet has more than adequate potency for clinical evaluation and is safe with no detectable levels of glycosides. These observations augur well for evaluating bean gum in human clinical studies to minimize virus infection/transmission.

HerpDock: A GUI-based gateway to HSV-1 molecular docking insights

Herpes Simplex Virus 1 (HSV-1) is a member of the alpha-Herpesviridae family, with over 60 % of the global population being seropositive. HSV-1 can cause a range of symptoms, from mild discomfort to severe, life-threatening complications. The emergence of HSV-1-resistant strains and the diminishing effectiveness of current antiviral treatments highlight the urgent need for new antiviral drugs. Computational molecular docking studies can offer valuable insights for the development of novel antiviral compounds targeting HSV-1. To address this need, we have developed HerpDock, an open-source Graphical User Interface (GUI) program designed for molecular docking, high-throughput virtual screening, and absorption, distribution, metabolism, and elimination (ADME) studies. HerpDock stands out as a unique, user-friendly pipeline that extends beyond the capabilities of existing docking programs based on AutoDock Vina. It requires only the ligand name or structure from the user, as it already includes optimized structures of numerous HSV-1 viral proteins and relevant host proteins. With just a few clicks, HerpDock performs comprehensive docking studies, result analysis, and visualization, making it particularly valuable for Herpes researchers without a bioinformatics background. HerpDock is freely available at https://github.com/Sudhk24/Herpdock.

Formulation and Characterization of β-Cyclodextrins-Nitazoxanide Inclusion Complexes: Enhanced Solubility, In Vitro Drug Release, and Antiviral Activity in Vero Cells

Background/Objectives: Nitazoxanide (NTX) exhibits promising therapeutic potential; its effectiveness is constrained by its low oral bioavailability due to its poor water solubility and limited permeability. Methods: This study focused on developing a complex of NTX with β-cyclodextrins (β-CDs), specifically β-CD and hydroxypropyl-β-cyclodextrin (Hβ-CD), to enhance the solubility and antiviral activity of NTX. Results: The formation of the β-CD:NTX in an aqueous solution was verified using UV-visible spectroscopy, confirming a 1:1 inclusion complex. Characterization of the solid β-CD:NTX complexes was confirmed via FTIR, X-ray diffraction (XRD), scanning electron microscopy (SEM), and DSC-TGA analyses. Molecular docking studies revealed that the NTX thiazole ring with the nitro group was positioned within the β-CDs cavity, while the benzene ring remained outside. Phase solubility tests showed that β-CD:NTX complexes were formed with high stability constants, demonstrating a linear increase in NTX solubility as the β-CD concentration increased. Dissolution tests revealed rapid and nearly complete NTX release within 90 min for β-CD:NTX and Hβ-CD:NTX complexes. The β-CD:NTX complexes were tested for their antiviral activity against Herpes simplex virus (HSV-1) cultures. Results showed that the Hβ-CD:NTX complex had significantly higher antiviral efficacy than β-CD:NTX and free NTX alone. Moreover, cytotoxicity and cellular uptake studies on Vero cells indicated that the Hβ-CD:NTX complex demonstrated lower cytotoxicity and had the highest IC50 value, followed by β-CD:NTX and free NTX. Conclusions: These findings suggest that Hβ-CD:NTX inclusion complexes may serve as effective carriers for delivering NTX in HSV-1 treatments using Vero cell models.

Immunological Considerations for the Development of an Effective Herpes Vaccine

Research is underway to develop a vaccine to prevent and cure infection from herpes simplex virus (HSV). It emphasizes the critical need for immunization to address public health issues and the shortcomings of existing treatment options. Furthermore, studies on the HSV vaccine advance the field of immunology and vaccine creation, which may help in the battle against other viral illnesses. The current lack of such a vaccine is, in part, due to herpes viral latency in sensory ganglions. Current vaccines rely on tissue-resident memory CD8+ T cells, which are known to provide protection against subsequent HSV reinfection and reactivation without correlating with other immune subsets. For that reason, there is no effective vaccine that can provide protection against latent or recurrent herpes infection. This review focuses on conventional methods for evaluating the efficacy of a herpes vaccine using differential CD8+ T cells and important unaccounted immune aspects for designing an effective vaccine against herpes.

Management of Refractory/Resistant Herpes Simplex Virus Infections in Haematopoietic Stem Cell Transplantation Recipients: A Literature Review

Herpes simplex virus (HSV) infections in allogeneic haematopoietic stem cell transplantation (HSCT) recipients pose significant challenges, with higher incidence, severity, and risk of emergence of resistance to antivirals due to impaired T-cell mediated immunity. This literature review focuses on acyclovir-refractory/resistant HSV infections in HSCT recipients. The review addresses the efficacy of antiviral prophylaxis, the incidence of acyclovir-refractory/resistant HSV infections, and the identification of risk factors and potential prognostic impact associated with those infections. Additionally, alternative therapeutic options are discussed. While acyclovir prophylaxis demonstrates a significant benefit in reducing HSV infections in HSCT recipients and, in some cases, overall mortality, concerns arise about the emergence of drug-resistant HSV strains. Our systematic review reports a median incidence of acyclovir-resistant HSV infections of 16.1%, with an increasing trend in recent years. Despite limitations in available studies, potential risk factors of emergence of HSV resistance to acyclovir include human leucocyte antigen (HLA) mismatches, myeloid neoplasms and acute leukaemias, and graft-versus-host disease (GVHD). Limited evidences suggest a potentially poorer prognosis for allogeneic HSCT recipients with acyclovir-refractory/resistant HSV infection. Alternative therapeutic approaches, such as foscarnet, cidofovir, topical cidofovir, optimised acyclovir dosing, and helicase-primase inhibitors offer promising options but require further investigations. Overall, larger studies are needed to refine preventive and therapeutic strategies for acyclovir-refractory/resistant HSV infections in allogeneic HSCT recipients and to identify those at higher risk.

Antiviral Activities of Mastoparan-L-Derived Peptides against Human Alphaherpesvirus 1

Human alphaherpesvirus 1 (HSV-1) is a significantly widespread viral pathogen causing recurrent infections that are currently incurable despite available treatment protocols. Studies have highlighted the potential of antimicrobial peptides sourced from Vespula lewisii venom, particularly those belonging to the mastoparan family, as effective against HSV-1. This study aimed to demonstrate the antiviral properties of mastoparans, including mastoparan-L [I5, R8], mastoparan-MO, and [I5, R8] mastoparan, against HSV-1. Initially, Vero cell viability was assessed in the presence of these peptides, followed by the determination of antiviral activity, mechanism of action, and dose-response curves through plaque assays. Structural analyses via circular dichroism and nuclear magnetic resonance were conducted, along with evaluating membrane fluidity changes induced by [I5, R8] mastoparan using fluorescence-labeled lipid vesicles. Cytotoxic assays revealed high cell viability (>80%) at concentrations of 200 µg/mL for mastoparan-L and mastoparan-MO and 50 µg/mL for [I5, R8] mastoparan. Mastoparan-MO and [I5, R8] mastoparan exhibited over 80% HSV-1 inhibition, with up to 99% viral replication inhibition, particularly in the early infection stages. Structural analysis indicated an α-helical structure for [I5, R8] mastoparan, suggesting effective viral particle disruption before cell attachment. Mastoparans present promising prospects for HSV-1 infection control, although further investigation into their mechanisms is warranted.

Carnosic Acid Inhibits Herpes Simplex Virus Replication by Suppressing Cellular ATP Synthesis

Acquiring resistance against antiviral drugs is a significant problem in antimicrobial therapy. In order to identify novel antiviral compounds, the antiviral activity of eight plants indigenous to the southern region of Hungary against herpes simplex virus-2 (HSV-2) was investigated. The plant extracts and the plant compound carnosic acid were tested for their effectiveness on both the extracellular and intracellular forms of HSV-2 on Vero and HeLa cells. HSV-2 replication was measured by a direct quantitative PCR (qPCR). Among the tested plant extracts, Salvia rosmarinus (S. rosmarinus) exhibited a 90.46% reduction in HSV-2 replication at the 0.47 μg/mL concentration. Carnosic acid, a major antimicrobial compound found in rosemary, also demonstrated a significant dose-dependent inhibition of both extracellular and intracellular forms of HSV-2. The 90% inhibitory concentration (IC90) of carnosic acid was between 25 and 6.25 μg/mL. Proteomics and high-resolution respirometry showed that carnosic acid suppressed key ATP synthesis pathways such as glycolysis, citrate cycle, and oxidative phosphorylation. Inhibition of oxidative phosphorylation also suppressed HSV-2 replication up to 39.94-fold. These results indicate that the antiviral action of carnosic acid includes the inhibition of ATP generation by suppressing key energy production pathways. Carnosic acid holds promise as a potential novel antiviral agent against HSV-2.

Efficacy of photobiomodulation therapy in recurrent herpes labialis management: a randomized controlled trial

OBJECTIVES

This study is aimed at assessing the therapeutic efficacy of photobiomodulation therapy (PBMT) for the management of recurrent herpes labialis (RHL) by evaluating both pain and clinical recovery.

MATERIAL AND METHODS

A randomized, double-blind, controlled trial was conducted on 40 patients with RHL, and they were randomly divided into two groups, where 20 patients received treatment with PBMT (650 nm, 100 mW, 4.7 J/cm2), continuous mode, for 120 s, and placebo cream, while another 20 patients (control group) were treated with acyclovir cream 5% (5 times/5 days) and passive laser. Pain was assessed at five different times. The day when the complete disappearance of the pain was observed and the day when the crust fell off spontaneously were also recorded.

RESULTS

The pain level in the control group was significantly higher than that in the PBMT group after the second application of the laser, while the differences were not significant between the two groups at other times. The pain in the PBMT group disappeared faster than that in the control group, but the difference was not significant in terms of clinical recovery.

CONCLUSIONS

Photobiomodulation therapy of herpes labialis reduced pain significantly faster than acyclovir, but there was no difference in healing time between the groups in light of the parameters used in this study.

CLINICAL RELEVANCE

PBMT is a promising treatment that may be an effective alternative to acyclovir in the management of recurrent herpes labialis.

TRIAL REGISTRATION ISRCTN

com ID: ISRCTN87606522.

Antiherpetic Activity of a Root Exudate from Solanum lycopersicum

The rise of drug resistance to antivirals poses a significant global concern for public health; therefore, there is a pressing need to identify novel compounds that can effectively counteract strains resistant to current antiviral treatments. In light of this, researchers have been exploring new approaches, including the investigation of natural compounds as alternative sources for developing potent antiviral therapies. Thus, this work aimed to evaluate the antiviral properties of the organic-soluble fraction of a root exudate derived from the tomato plant Solanum lycopersicum in the context of herpesvirus infections. Our findings demonstrated that a root exudate from Solanum lycopersicum exhibits remarkable efficacy against prominent members of the family Herpesviridae, specifically herpes simplex virus type 1 (HSV-1) (EC50 25.57 µg/mL, SI > 15.64) and human cytomegalovirus (HCMV) (EC50 9.17 µg/mL, SI 32.28) by inhibiting a molecular event during the herpesvirus replication phase. Moreover, the phytochemical fingerprint of the Solanum lycopersicum root exudate was characterized through mass spectrometry. Overall, these data have unveiled a novel natural product with antiherpetic activity, presenting a promising and valuable alternative to existing drugs.

Korean Chestnut Honey Suppresses HSV-1 Infection by Regulating the ROS-NLRP3 Inflammasome Pathway

Herpes simplex virus 1 (HSV-1) is double-stranded DNA virus that belongs to the Orthoherpesviridae family. It causes serious neurological diseases of the central nervous system, such as encephalitis. The current U.S. Food and Drug Administration (FDA)-approved drugs for preventing HSV-1 infection include acyclovir (ACV) and valacyclovir; however, their long-term use causes severe side effects and often results in the emergence of drug-resistant strains. Therefore, it is important to discover new antiviral agents that are safe and effective against HSV-1 infection. Korean chestnut honey (KCH) has various pharmacological activities, such as antioxidant, antibacterial, and anti-inflammation effects; however, antiviral effects against HSV-1 have not yet been reported. Therefore, we determined the antiviral activity and mechanism of action of KCH after HSV-1 infection on the cellular level. KCH inhibited the HSV-1 infection of host cells through binding and virucidal steps. KCH decreased the production of reactive oxygen species (ROS) and calcium (Ca2+) following HSV-1 infection and suppressed the production of inflammatory cytokines by inhibiting nuclear factor kappa-light-chain-enhancer of activated B cells (NF-кB) activity. Furthermore, we found that KCH inhibited the expression of the nod-like receptor protein 3 (NLRP3) inflammasome during HSV-1 infection. Taken together, the antiviral effects of KCH occur through multiple targets, including the inhibition of viral replication and the ROS-mediated NLRP3 inflammasome pathway. Our findings suggest that KCH has potential for the treatment of HSV-1 infection and related diseases.