Herpes Simplex Virus Research Articles

Atypical presentation of herpes simplex virus 2 primary infection: a case report

BackgroundCervicitis, an infectious or noninfectious inflammation of the cervix, encompasses a wide range of clinical conditions, from asymptomatic infections to severe lesions, making its diagnosis difficult. Acute cervicitis may develop into pelvic inflammatory disease. In patients with cervicitis, current guidelines recommend testing for herpes simplex virus when external genital lesions are present. Here, we present the case of a patient with an atypical primary herpes simplex virus 2 infection manifesting as cervicitis without genital lesions.Case presentationA 29-year-old Caucasian woman was hospitalized for pelvic inflammatory disease. The patient complained of severe suprapubic pain, fever, and heavy vaginal discharge. The external genitalia were unremarkable, so empirical antibiotic treatment was initiated. Despite 48 hours of well-administered antibiotic therapy, her complaints persisted. Polymerase chain reaction for possible microbial causes was negative for Chlamydia trachomatis and Neisseria gonorrhoeae. There was no bacterial vaginosis. Repeat gynecological examinations with endovaginal ultrasound revealed an enlarged cervix, and pelvic magnetic resonance imaging supported a diagnosis of cervicitis. At this point, additional screening for other sexually transmitted infections and infectious disease-related etiologies of cervicitis was performed, and the polymerase chain reaction analysis of newly isolated samples was positive for herpes simplex virus 2. No antiviral treatment was initiated given the delay in diagnosing herpes simplex virus 2 infection and the slow but spontaneous abatement of symptoms.ConclusionHerpes simplex virus infection should be considered as a possible cause of cervicitis, even in the absence of typical genital lesions. Early detection of herpes simplex virus allows early treatment, helping to reduce the duration and severity of symptoms and therefore potentially reducing recurrences and improving disease control. These data and data from future cases might spur changes in the guidelines on cervicitis testing and treatment.

Mouse guanylate-binding proteins of the chromosome 3 cluster do not mediate antiviral activity in vitro or in mouse models of infection

Dynamin-like GTPase proteins, including myxoma (Mx) and guanylate-binding proteins (GBPs), are among the many interferon stimulated genes induced following viral infections. While studies report that human (h)GBPs inhibit different viruses in vitro, few have convincingly demonstrated that mouse (m)GBPs mediate antiviral activity, although mGBP-deficient mice have been used extensively to define their importance in immunity to diverse intracellular bacteria and protozoa. Herein, we demonstrate that individual (overexpression) or collective (knockout (KO) mice) mGBPs of the chromosome 3 cluster (mGBPchr3) do not inhibit replication of five viruses from different virus families in vitro, nor do we observe differences in virus titres recovered from wild type versus mGBPchr3 KO mice after infection with three of these viruses (influenza A virus, herpes simplex virus type 1 or lymphocytic choriomeningitis virus). These data indicate that mGBPchr3 do not appear to be a major component of cell-intrinsic antiviral immunity against the diverse viruses tested in our studies.

International treatment outcomes of neonates on extracorporeal membrane oxygenation (ECMO) with persistent pulmonary hypertension of the newborn (PPHN): a systematic review

BackgroundPPHN is a common cause of neonatal respiratory failure and is still a serious condition and associated with high mortality.ObjectivesTo compare the demographic variables, clinical characteristics, and treatment outcomes in neonates with PHHN who underwent ECMO and survived compared to neonates with PHHN who underwent ECMO and died.MethodsWe adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline and searched ProQuest, Medline, Embase, PubMed, CINAHL, Wiley online library, Scopus and Nature for studies on the development of PPHN in neonates who underwent ECMO, published from January 1, 2010 to May 31, 2023, with English language restriction.ResultsOf the 5689 papers that were identified, 134 articles were included in the systematic review. Studies involving 1814 neonates with PPHN who were placed on ECMO were analyzed (1218 survived and 594 died). Neonates in the PPHN group who died had lower proportion of normal spontaneous vaginal delivery (6.4% vs 1.8%; p value > 0.05) and lower Apgar scores at 1 min and 5 min [i.e., low Apgar score: 1.5% vs 0.5%, moderately abnormal Apgar score: 10.3% vs 1.2% and reassuring Apgar score: 4% vs 2.3%; p value = 0.039] compared to those who survived. Neonates who had PPHN and died had higher proportion of medical comorbidities such as omphalocele (0.7% vs 4.7%), systemic hypotension (1% vs 2.5%), infection with Herpes simplex virus (0.4% vs 2.2%) or Bordetella pertussis (0.7% vs 2%); p = 0.042. Neonates with PPHN in the death group were more likely to present due to congenital diaphragmatic hernia (25.5% vs 47.3%), neonatal respiratory distress syndrome (4.2% vs 13.5%), meconium aspiration syndrome (8% vs 12.1%), pneumonia (1.6% vs 8.4%), sepsis (1.5% vs 8.2%) and alveolar capillary dysplasia with misalignment of pulmonary veins (0.1% vs 4.4%); p = 0.019. Neonates with PPHN who died needed a longer median time of mechanical ventilation (15 days, IQR 10 to 27 vs. 10 days, IQR 7 to 28; p = 0.024) and ECMO use (9.2 days, IQR 3.9 to 13.5 vs. 6 days, IQR 3 to 12.5; p = 0.033), and a shorter median duration of hospital stay (23 days, IQR 12.5 to 46 vs. 58.5 days, IQR 28.2 to 60.7; p = 0.000) compared to the neonates with PPHN who survived. ECMO-related complications such as chylothorax (1% vs 2.7%), intracranial bleeding (1.2% vs 1.7%) and catheter-related infections (0% vs 0.3%) were more frequent in the group of neonates with PPHN who died (p = 0.031).ConclusionECMO in the neonates with PPHN who failed supportive cardiorespiratory care and conventional therapies has been successfully utilized with a neonatal survival rate of 67.1%. Mortality in neonates with PPHN who underwent ECMO was highest in cases born via the caesarean delivery mode or neonates who had lower Apgar scores at birth. Fatality rate in neonates with PPHN who underwent ECMO was the highest in patients with higher rate of specific medical comorbidities (omphalocele, systemic hypotension and infection with Herpes simplex virus or Bordetella pertussis) or cases who had PPHN due to higher rate of specific etiologies (congenital diaphragmatic hernia, neonatal respiratory distress syndrome and meconium aspiration syndrome). Neonates with PPHN who died may need a longer time of mechanical ventilation and ECMO use and a shorter duration of hospital stay; and may experience higher frequency of ECMO-related complications (chylothorax, intracranial bleeding and catheter-related infections) in comparison with the neonates with PPHN who survived.

Protective Mechanisms of Vaginal Lactobacilli against Sexually Transmitted Viral Infections.

The healthy cervicovaginal microbiota is dominated by various Lactobacillus species, which support a condition of eubiosis. Among their many functions, vaginal lactobacilli contribute to the maintenance of an acidic pH, produce antimicrobial compounds, and modulate the host immune response to protect against vaginal bacterial and fungal infections. Increasing evidence suggests that these beneficial bacteria may also confer protection against sexually transmitted infections (STIs) caused by viruses such as human papillomavirus (HPV), human immunodeficiency virus (HIV) and herpes simplex virus (HSV). Viral STIs pose a substantial public health burden globally, causing a range of infectious diseases with potentially severe consequences. Understanding the molecular mechanisms by which lactobacilli exert their protective effects against viral STIs is paramount for the development of novel preventive and therapeutic strategies. This review aims to provide more recent insights into the intricate interactions between lactobacilli and viral STIs, exploring their impact on the vaginal microenvironment, host immune response, viral infectivity and pathogenesis, and highlighting their potential implications for public health interventions and clinical management strategies.

Import of extracellular 2′-3′cGAMP by the folate transporter, SLC19A1, establishes an antiviral response that limits herpes simplex virus-1

Recently it was discovered that extracellular 2′-3′cGAMP can activate the STING pathway in a cGAS-independent fashion by being transported across the cell membrane via the folate transporter, SLC19A1, the first identified extracellular antiporter of this critical signaling molecule in cancer cells. We hypothesized that this non-canonical activation of STING pathway would function to establish an antiviral state similar to that seen with the paracrine antiviral activities of interferon. Herein, we report that treatment of the monocytic cell line, THP-1 cells and SH-SY5Y neuronal cell line with exogenous 2′-3′cGAMP induces interferon production and establishes an antiviral state that limits herpes simplex virus-1 (HSV-1), a ubiquitous virus with high seropositivity in the human population. Using either pharmaceutical inhibition or genetic knockout of SLC19A1 blocks the 2′-3′cGAMP-induced inhibition of viral replication. Our data indicate SLC19A1 functions as a newly identified antiviral mediator for extracellular 2′-3′cGAMP. This work presents novel and important findings about an antiviral mechanism which information could aid in the development of better antiviral drugs in the future.

Centrifugal Microfluidic Cell Culture Platform for Physiologically Relevant Virus Infection Studies: A Case Study with HSV-1 Infection of Periodontal Cells.

Static well plates remain the gold standard to study viral infections in vitro, but they cannot accurately mimic dynamic viral infections as they occur in the human body. Therefore, we established a dynamic cell culture platform, based on centrifugal microfluidics, to study viral infections in perfusion. To do so, we used human primary periodontal dental ligament (PDL) cells and herpes simplex virus-1 (HSV-1) as a case study. By microscopy, we confirmed that the PDL cells efficiently attached and grew in the chip. Successful dynamic viral infection of perfused PDL cells was monitored using fluorescent imaging and RT-qPCR-based experiments. Remarkably, viral infection in flow resulted in a gradient of HSV-1-infected cells gradually decreasing from the cell culture chamber entrance towards its end. The perfusion of acyclovir in the chip prevented HSV-1 spreading, demonstrating the usefulness of such a platform for monitoring the effects of antiviral drugs. In addition, the innate antiviral response of PDL cells, measured by interferon gene expression, increased significantly over time in conventional static conditions compared to the perfusion model. These results provide evidence suggesting that dynamic viral infections differ from conventional static infections, which highlights the need for more physiologically relevant in vitro models to study viral infections.

Case Report: Herpes simplex virus type 2 (HSV-2) meningo-encephalitis associated with traumatic brain injury – a case report from Lao PDR

Background Neurological symptoms following head trauma are common; however, the cause may not always be obvious. In the absence of open wounds, fractures, or surgical interventions, infectious causes may not be considered, and investigations may not be targeted to investigate this possibility. Case A 39-year-old male presented with a severe headache, reduced consciousness, and confusion. Two days earlier, he had been discharged from the hospital, where he had been treated for traumatic brain injury with subarachnoid hemorrhage following a road traffic accident. Herpes simplex virus type 2 (HSV-2) was detected in the cerebrospinal fluid, confirming the diagnosis of viral meningoencephalitis. He was treated with oral aciclovir for two weeks and achieved full neurological recovery. Conclusions This case highlights the risk of viral reactivation following trauma, particularly head injuries. Central nervous system infections should be considered in cases of delayed deterioration following trauma. The optimal treatment of herpes simplex virus (HSV) encephalitis may be challenging in resource-limited settings.

Herpes Simplex Virus 1 Envelope Glycoprotein C Shields Glycoprotein D to Protect Virions from Entry-Blocking Antibodies.

Herpes simplex virus 1 (HSV-1) gD interaction with the host cell receptor nectin-1 triggers the membrane fusion cascade during viral entry. Potent neutralizing antibodies to gD prevent receptor-binding or prevent gD interaction with gH/gL critical for fusion. HSV has many strategies to evade host immune responses. We investigated the ability of virion envelope gC to protect envelope gD from antibody neutralization. HSV-1 lacking gC was more sensitive to neutralization by anti-gD monoclonal antibodies than a wild type rescuant virus. gD in the HSV-1 gC-null viral envelope had enhanced reactivity to anti-gD antibodies compared to wild type. HSV-1 ΔgC binding to the nectin-1 receptor was more readily inhibited by a neutralizing anti-gD monoclonal antibody. HSV-1 ΔgC was also more sensitive to inhibition by soluble nectin-1 receptor. The viral membrane protein composition of HSV-1 ΔgC was equivalent to that of wild type, suggesting that the lack of gC is responsible for the increased reactivity of gD-specific antibodies and the consequent increased susceptibility to neutralization by those antibodies. Together, the results suggest that gC in the HSV-1 envelope shields both receptor-binding domains and gH/gL-interacting domains of gD from neutralizing antibodies, facilitating HSV cell entry.

Type 2 herpes simplex virus-induced anti-N-methyl-D-aspartate receptor encephalitis responsive to immunoglobulin monotherapy.

Herpes simplex virus-2 encephalitis (HSV2E) in immunocompetent adults is exceptionally rare, and the subsequent onset of autoimmune encephalitis after HSV2E is even less common. This report presents the inaugural Chinese case of anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) induced by HSV2E, confirmed via metagenomic next-generation sequencing (mNGS). The patient demonstrated a favorable response to intravenous immunoglobulin (IVIG) monotherapy. This case emphasizes the importance of considering autoimmune encephalitis in patients exhibiting new or recurrent neurological symptoms after HSV2E recovery. Comprehensive mNGS and neuronal antibody testing are essential for timely diagnosis. Moreover, IVIG monotherapy can serve as an effective treatment for NMDARE induced by HSV2, providing a viable alternative, particularly when steroid therapy is contraindicated.

CFTR Inhibitors Display Antiviral Activity against Herpes Simplex Virus.

The cystic fibrosis transmembrane conductance regulator (CFTR), a cAMP-dependent Cl- channel, is closely associated with multiple pathogen infections, such as SARS-CoV-2. However, whether the function of the CFTR is involved in herpes simplex virus (HSV) infection has not been reported. To evaluate the association of CFTR activity with HSV infection, the antiviral effect of CFTR inhibitors in epithelial cells and HSV-infected mice was tested in this study. The data showed that treatment with CFTR inhibitors in different concentrations, Glyh-101 (5-20 μM), CFTRi-172 (5-20 μM) and IOWH-032 (5-20 μM), or the gene silence of the CFTR could suppress herpes simplex virus 1 (HSV-1) and herpes simplex virus 2 (HSV-2) replication in human HaCaT keratinocytes cells, and that a CFTR inhibitor, Glyh-101 (10-20 μM), protected mice from HSV-1 and HSV-2 infection. Intracellular Cl- concentration ([Cl-]i) was decreased after HSV infection via the activation of adenylyl cyclase (AC)-cAMP signaling pathways. CFTR inhibitors (20 μM) increased the reduced [Cl-]i caused by HSV infection in host epithelial cells. Additionally, CFTR inhibitors reduced the activity and phosphorylation of SGK1 in infected cells and tissues (from the eye and vagina). Our study found that CFTR inhibitors can effectively suppress HSV-1 and HSV-2 infection, revealing a previously unknown role of CFTR inhibitors in HSV infection and suggesting new perspectives on the mechanisms governing HSV infection in host epithelial cells, as well as leading to potential novel treatments.

Synthetic Naphthoquinone Inhibits Herpes Simplex Virus Type-1 Replication Targeting Na+, K+ ATPase.

Since 1970 acyclovir (ACV) has been the reference drug in treating herpes simplex virus (HSV) infections. However, resistant herpes simplex virus type 1 (HSV-1) strains have emerged, narrowing the treatment efficacy. The antiviral activity of classical Na+, K+ ATPase enzyme (NKA) inhibitors linked the viral replication to the NKA's activity. Herein, we evaluated the anti-HSV-1 activity of synthetic naphthoquinones, correlating their antiviral activity with NKA inhibition. We tested seven synthetic naphthoquinones initially at 50 μM on HSV-1-infected African green monkey kidney cells (VERO cells). Only one compound, 2-hydroxy-3-(2-thienyl)-1,4-naphthoquinone (AN-06), exhibited higher antiviral activity with a low cytotoxicity. AN-06 reduced the viral titer of 9 (log10) to 1.32 (log10) and decreased the steps of attachment and penetration. The addition of AN-06 up to 20 h postinfection (hpi) interfered with the viral cycle. The viral infection alone increases NKA activity 3 h postinfection (hpi), scaling up to 6 hpi. The addition of AN-06 in a culture infected with HSV-1 decreased NKA activity, suggesting that its antiviral action is linked to NKA inhibition. Also, docking results showed that this compound binds at the same site of NKA in which adenosine triphosphate (ATP) binds. AN-06 exhibited promising pharmacokinetic and toxicology properties. Thus, we postulate that AN-06 may be a good candidate for antiviral compounds with a mechanism of action targeting NKA activity.

Daxx mediated histone H3.3 deposition on HSV-1 DNA restricts genome decompaction and the progression of immediate-early transcription.

Herpesviruses are ubiquitous pathogens that cause a wide range of disease. Upon nuclear entry, their genomes associate with histones and chromatin modifying enzymes that regulate the progression of viral transcription and outcome of infection. While the composition and modification of viral chromatin has been extensively studied on bulk populations of infected cells by chromatin immunoprecipitation, this key regulatory process remains poorly defined at single-genome resolution. Here we use high-resolution quantitative imaging to investigate the spatial proximity of canonical and variant histones at individual Herpes Simplex Virus 1 (HSV-1) genomes within the first 90 minutes of infection. We identify significant population heterogeneity in the stable enrichment and spatial proximity of canonical histones (H2A, H2B, H3.1) at viral DNA (vDNA) relative to established promyelocytic leukaemia nuclear body (PML-NB) host factors that are actively recruited to viral genomes upon nuclear entry. We show the replication-independent histone H3.3/H4 chaperone Daxx to cooperate with PML to mediate the enrichment and spatial localization of variant histone H3.3 at vDNA that limits the rate of HSV-1 genome decompaction to restrict the progress of immediate-early (IE) transcription. This host response is counteracted by the viral ubiquitin ligase ICP0, which degrades PML to disperse Daxx and variant histone H3.3 from vDNA to stimulate the progression of viral genome expansion, IE transcription, and onset of HSV-1 replication. Our data support a model of intermediate and sequential histone assembly initiated by Daxx that limits the rate of HSV-1 genome decompaction independently of the stable enrichment of histones H2A and H2B at vDNA required to facilitate canonical nucleosome assembly. We identify HSV-1 genome decompaction upon nuclear infection to play a key role in the initiation and functional outcome of HSV-1 lytic infection, findings pertinent to the transcriptional regulation of many nuclear replicating herpesvirus pathogens.

Cytotoxic and Anti-HSV-1 Effects of Caulerpin Derivatives.

Marine organisms represent a potential source of secondary metabolites with various therapeutic properties. However, the pharmaceutical industry still needs to explore the algological resource. The species Caulerpa lamouroux Forssk presents confirmed biological activities associated with its major compound caulerpin, such as antinociceptive, spasmolytic, antiviral, antimicrobial, insecticidal, and cytotoxic. Considering that caulerpin is still limited, such as low solubility or chemical instability, it was subjected to a structural modifications test to establish which molecular regions could accept structural modification and to elucidate the cytotoxic bioactive structure in Vero cells (African green monkey kidney cells, Cercopithecus aethiops; ATCC, Manassas, VA, USA) and antiviral to Herpes simplex virus type 1. Substitution reactions in the N-indolic position with mono- and di-substituted alkyl, benzyl, allyl, propargyl, and ethyl acetate groups were performed, in addition to conversion to their acidic derivatives. The obtained analogs were submitted to cytotoxicity and antiviral activity screening against Herpes simplex virus type 1 by the tetrazolium microculture method. From the semi-synthesis, 14 analogs were obtained, and 12 are new. The cytotoxicity assay showed that caulerpin acid and N-ethyl-substituted acid presented cytotoxic concentrations referring to 50% of the maximum effect of 1035.0 µM and 1004.0 µM, respectively, values significantly higher than caulerpin. The antiviral screening of the analogs revealed that the N-substituted acids with methyl and ethyl groups inhibited Herpes simplex virus type 1-induced cytotoxicity by levels similar to the positive control acyclovir.

Causality between herpes virus infections and allograft dysfunction after tissue and organ transplantation: a two-sample bidirectional Mendelian randomization study.

Observational studies have suggested that herpes virus infections increase the risk of allograft dysfunction after tissue and organ transplantation, but it is still unclear whether this association is causal. The aim of this study was to assess the causal relationship between four herpes virus infections and allograft dysfunction. We used two-sample bidirectional Mendelian randomization (MR) to investigate the causality between four herpes virus infections - cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV) and varicella zoster virus (VZV) - and allograft dysfunction after tissue and organ transplantation. Based on summary data extracted from genome-wide association studies (GWAS), we chose eligible single nucleotide polymorphisms (SNPs) as instrumental variables. The Inverse variance weighted (IVW) method was used as the main analysis method, supplemented by Weighted median and MR-Egger analyses. The MR-PRESSO test, MR-Egger intercept test, heterogeneity test, leave-one-out analysis and funnel plot were used to analyze the sensitivity of MR results. We found EBV early antigen-D (EA-D) antibody levels and shingles were the only two variables associated with an increased risk of allograft dysfunction. No evidence of allograft dysfunction increasing the risk of the four herpes virus infections was observed. Sensitivity analyses confirmed the robustness of our results. Our results suggest that EBV and VZV are involved in graft rejection or dysfunction. However, the relationship between CMV and HSV infections and allograft dysfunction remains unclear and requires further clarification.

Etiology, Characteristics, and Outcomes of Neonatal Liver Failure: Lessons Learned Over the Last 3 Decades

To evaluate trends in etiology and outcomes of neonatal liver failure (NLF) over 30years retrospectively at a single institution. Inclusion criteria for this retrospective cohort study were babies presenting at a chronological age of ≤28days between 1991 and 2020 with prothrombin time≥20seconds and biochemical liver injury. Demographics, etiology, laboratory investigations, need for extrahepatic organ support, acute kidney injury, and intervention with liver transplant (LT) were recorded. Survival outcomes were measured as discharge from the hospital alive with native liver or LT. The study period was stratified into 3 10-year blocks. Trends were analyzed for hospital admissions, etiology, and survival outcomes. One hundred twenty-six babies met the NLF criteria. Admissions to the hospital increased from 21 in 1991-2000 to 65 in 2011-2020. An increasing trend in infectious and metabolic causes, while a decreasing trend in indeterminate etiology, was noted. Survival with native liver improved from 23.8% in 1991-2000 to 55.4% in 2011-20 (P=.021), and mortality reduced from 52.4% to 35.4% during the same periods (P=.213). Twenty-three (18.2%) neonates received LT. Post-LT survival outcomes were 100% for gestational alloimmune liver disease, 66.6% in the indeterminate group, and 25% for herpes simplex virus. Specific etiologies (gestational alloimmune liver disease, OR=0.07 [0-0.77, P=.048]), presence of acute kidney injury (OR=6.22 [1.45, 29.38, P=.015]) and need for inotropes (OR=6.22 [1.45, 29.38, P=.028]) influenced mortality in multivariable logistic regression analysis. In the last 30years, advances in diagnosis, treatment, and increasing experience with LT have improved survival in NLF.

Practical updates in clinical antiviral resistance testing.

The laboratory diagnosis of antiviral resistance is a quickly changing field due to new drug availability, the sunsetting of older drugs, the development of novel technologies, rapid viral evolution, and the financial/logistic pressures of the clinical laboratory. This mini-review summarizes the current state of clinically available antiviral resistance testing in the United States in 2024, covering the most commonly used test methods, mechanisms, and clinical indications for herpes simplex virus, cytomegalovirus, human immunodeficiency virus, influenza, hepatitis B virus, and hepatitis C virus drug resistance testing. Common themes include the move away from phenotypic to genotypic methods for first-line clinical testing, as well as uncertainty surrounding the clinical meaningfulness of minority variant detection as next-generation sequencing methods have become more commonplace.

Rapid diagnosis of herpes simplex virus 1 and 2 bloodstream infections utilizing a sample-to-answer platform.

Rapid, accurate, and definitive diagnosis of herpes simplex virus (HSV) infections is crucial in clinical settings for patient management. The absence of FDA-authorized molecular assays for HSV-1/2 detection in blood, coupled with a lack of consensus on the optimal sample type, underscores the need for improved diagnostic methods. Furthermore, rapid diagnosis of HSV bloodstream infections enables timely administration of antiviral treatment, influences patient management decisions for those at high risk, and can contribute to shorter hospital stays, thereby reducing healthcare costs.

Sexually transmitted infections and migration in Uganda: a population-based study

ObjectivesMigration is associated with increased risk of HIV infection in Africa, but evidence about non-HIV sexually transmitted infection (STI) burden among African migrants is limited.MethodsWe used data from the Sexually...

Bioadhesive gel containing 5 % acyclovir for the treatment of herpes labialis: Preclinical development

Acyclovir is widely indicated for the treatment of herpes labialis, an infection typically caused by herpes simplex virus 1 (HSV-1). The standard treatment is based on the use of this antiviral in conventional topical semi-solid formulations (ointments, creams or gels), which have limitations such as low skin adherence and poor patient compliance. On the other hand, therapeutic bioadhesive gels (TBG) are semi-solid formulations that form a thin and transparent polymeric film in situ, displaying superior cosmetic attributes than conventional semi-solid forms and offering improved skin maintenance and patient compliance. In this study, a TBG containing 5 % of acyclovir was developed and characterized in terms of assay, impurities, appearance, pH, viscosity, particle size and morphology and microbiology count, complying with specifications. Stability studies showed that acyclovir-TBG was stable for at least 3 years under the experimental conditions carried out according to the International Council for Harmonisation (ICH) guidelines. Moreover, its cosmetic attractiveness and film-forming ability were considered positive and the in vitro penetration studies revealed a 23.8-fold increase in acyclovir retained percentage in the skin compared to the reference product Zovirax® (11.9 vs 0.5 % after 24 h, respectively). Finally, in vivo skin and ocular irritation studies as well as dermal tolerance studies did not show any negative sign in the macroscopic and microscopic examination. Thus, the proposed formulation could be a good and safe alternative for the topical treatment of lesions caused by HSV-1.

Physiological oxygen concentration during sympathetic primary neuron culture improves neuronal health and reduces HSV-1 reactivation.

Herpes simplex virus-1 (HSV-1) establishes a latent infection in peripheral neurons and periodically reactivates in response to a stimulus to permit transmission. In vitro models using primary neurons are invaluable to studying latent infection because they use bona fide neurons that have undergone differentiation and maturation in vivo. However, culture conditions in vitro should remain as close to those in vivo as possible. This is especially important when considering minimizing cell stress, as it is a well-known trigger of HSV reactivation. We recently developed an HSV-1 model system that requires neurons to be cultured for extended lengths of time. Therefore, we sought to refine culture conditions to optimize neuronal health and minimize secondary effects on latency and reactivation. Here, we demonstrate that culturing primary neurons under conditions closer to physiological oxygen concentrations (5% oxygen) results in cultures with features consistent with reduced stress. Furthermore, culture in these lower oxygen conditions diminishes the progression to full HSV-1 reactivation despite minimal impacts on latency establishment and earlier stages of HSV-1 reactivation. We anticipate that our findings will be useful for the broader microbiology community as they highlight the importance of considering physiological oxygen concentration in studying host-pathogen interactions.