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Herpes Simplex Virus Type 1 (HSV-1) is a widespread human pathogen known for causing a spectrum of clinical manifestations, ranging from mild cold sores to severe complications like encephalitis. Understanding the strain-specific variations of HSV-1 is crucial for elucidating its pathogenesis and developing targeted therapeutic interventions. In this multifaceted study, we investigated the strain-specific characteristics of HSV-1 using an in vivo rat model. Firstly, a pilot study was conducted to assess the capacity of three HSV-1 strains (Fisher (F), KOS (K), and MacIntyre (M)) to induce cold sores in rats. Remarkably, the F strain exhibited pronounced pathogenicity, inducing erythema, swelling, and disrupted epidermis with ulceration, distinguishing it from the K and M strains. Subsequently, the treatment capability of intravenous acyclovir injection in HSV-1 F strain-infected rats was evaluated. Acyclovir treatment resulted in a significant reduction in HSV-1 viral copy numbers in serum and dissected neuronal tissues, particularly in the spinal cord, brain, and lower lip. Lastly, whole genome sequencing data revealed that high-impact mutations occurred in the K and M strains within the UL49, US2, and US3 genes. These mutations may play a pivotal role in influencing viral replication, dissemination, pathogenesis, and infectivity. In contrast, the moderate missense variant mutations detected in the US12, US8, UL3, UL30, UL31, and UL36 genes appeared to have no effect on viral pathogenesis and infectivity, based on RT-PCR data for spinal cord, trigeminal nerve, brain, and the lower lip. These strain-specific mutations underscore the dynamic nature of HSV-1 evolution. Collectively, our findings contribute to a deeper understanding of HSV-1 strain diversity and pave the way for the development of targeted therapeutic strategies against this medically significant virus., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

We present a case of a primigravida in her 30s who had a caesarean delivery of dichorionic diamniotic twins at 33 weeks of gestation. Her postpartum course was complicated by a herpes simplex virus (HSV) infection of her nipple, found after her neonates were diagnosed with HSV encephalitis. She was evaluated at her 3-week postpartum visit and reported that her neonates were concurrently admitted to the neonatal intensive care unit with disseminated neonatal HSV-1. The patient and her partner were in a monogamous relationship with no known history of HSV. Physical examination demonstrated a vertical fissure on the face of her right nipple and a small cluster of vesicles on her left hand. PCR swabs of the lesions were positive for HSV-1 at both locations. The patient was started on oral valacyclovir 1000 mg two times per day, topical acyclovir ointment applied 4-6 times per day and mupirocin ointment applied 3 times per day to her breast with resolution of her breast lesions. She was able to continue expressing her breastmilk with the help of a pump and then resumed breastfeeding once her infection was cleared. Her infants recovered after prolonged parenteral antiviral therapy with age-appropriate development at follow-up., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Introduction: Herpes simplex keratitis stands as a prominent factor contributing to infectious blindness among developed nations. On a global scale, over 60% of the population tests positive for herpes simplex virus type-1 (HSV-1). Despite these statistics, there is currently no vaccine available for the virus. Moreover, the conventional nucleoside drugs prescribed to patients are proving ineffective in addressing issues related to drug resistance, recurrence, latency, and the escalating risk of vision loss. Hence, it is imperative to continually explore all potential avenues to restrict the virus. This review article centers on the present treatment methods for HSV-1 keratitis (HSK), highlighting the ongoing clinical trials. It delves into the emerging drugs, their mode-of-action and future therapeutics., Areas Covered: The review focuses on the significance of a variety of small molecules targeting HSV-1 lifecycle at multiple steps. Peer-reviewed articles and abstracts were searched in MEDLINE, PubMed, Embase, and clinical trial websites., Expert Opinion: The exploration of small molecules that target specific pathways within the herpes lifecycle holds the potential for substantial impact on the antiviral pharmaceutical market. Simultaneously, the pursuit of disease-specific biomarkers has the capacity to usher in a transformative era in diagnostics within the field.

Introduction: Herpes simplex virus (HSV) is frequently detected in the respiratory tract of mechanically ventilated patients and is associated with a worse outcome. The aim of this study is to determine whether antiviral therapy in HSV-positive patients improves outcome., Methods and Analysis: Prospective, multicentre, open-label, randomised, controlled trial in parallel-group design. Adult, mechanically ventilated patients with pneumonia and HSV type 1 detected in bronchoalveolar lavage (≥10 5 copies/mL) are eligible for participation and will be randomly allocated (1:1) to receive acyclovir (10 mg/kg body weight every 8 hours) for 10 days (or until discharge from the intensive care unit if earlier) or no intervention (control group). The primary outcome is mortality measured at day 30 after randomisation (primary endpoint) and will be analysed with Cox mixed-effects model. Secondary endpoints include ventilator-free and vasopressor-free days up to day 30. A total of 710 patients will be included in the trial., Ethics and Dissemination: The trial was approved by the responsible ethics committee and by Germany's Federal Institute for Drugs and Medical Devices. The clinical trial application was submitted under the new Clinical Trials Regulation through CTIS (The Clinical Trials Information System). In this process, only one ethics committee, whose name is unknown to the applicant, and Germany's Federal Institute for Drugs and Medical Devices are involved throughout the entire approval process. Results will be published in a journal indexed in MEDLINE and CTIS. With publication, de-identified, individual participant data will be made available to researchers., Trial Registration Number: NCT06134492., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The knife-cut sign is a distinctive manifestation of herpes simplex virus (HSV) type 1 or HSV type 2 infection that has been described in at least 10 immunocompromised patients. It appears as an extremely painful linear erosion or fissure in an intertriginous area such as the body folds beneath the breast, or within the abdomen, or in the inguinal region. Also, concurrent HSV infection at other mucocutaneous sites, or viscera, or both have been observed. The patients had medical conditions (at least 9 patients) and/or immunosuppressive drug therapy (6 patients). The diagnosis of HSV infection was confirmed by viral culture (8 patients), biopsy (4 patients), direct fluorescence antibody testing (3 patients), immunohistochemistry staining (2 patients), polymerase chain reaction (2 patients), or Western blot serologic assay (1 patient). Knife-cut sign-associated HSV infection is potentially fatal; three patients died. However, clinical improvement or complete healing occurred in the patients who received oral valacyclovir (1 patient), or intravenous acyclovir (2 patients), or intravenous acyclovir followed by foscarnet (1 patient). In summary, HSV infection associated with a positive the knife-cut sign is a potentially fatal variant of HSV infection that occurs in the intertriginous areas of immunocompromised patients and usually requires intravenous antiviral therapy.

Herpetic geometric glossitis is a unique morphologic variant of HSV (herpes simplex virus) type 1 infection on the dorsum of the tongue that presents as an extremely painful linear central lingual fissure with a branched pattern. in the center of the tongue; there is a branched pattern of fissures that extend bilaterally from the central linear fissure. Herpetic geometric glossitis has been reported in 11 patients; 8 of these individuals were immunocompromised. Medical conditions and immunosuppressive medication treatment (7 patients) or only medical disorders (3 patients) or neither (1 patient) were present. HSV type 1 infection was diagnosed by viral culture in (7 patients), Tzanck preparation (2 patients) or clinically (2 patients). Mucocutaneous HSV infection at non-lingual locations--including the lips, labial mucosa, face and chest--were observed in 5 patients. All patients' symptoms and lesions responded to treatment with oral antiviral therapy: acyclovir (9 patients), famciclovir (1 patient) or valacyclovir (1 patient). The lingual pain and dorsal tongue fissures completely resolved completely within two to 14 days. In summary, herpetic geometric glossitis is a unique HSV type 1 infection, usually in immunocompromised patients, that occurs on the dorsal tongue and responds completely after treatment with orally administered antiviral therapy.

National guidelines give advice on topics which should be covered when counselling patients with a new diagnosis of genital herpes (HSV) with the aim of reducing transmissions. This three-site UK audit of documentation of counselling for patients with a new diagnosis of genital herpes reviewed the records of 284 patients. Documentation in all areas of counselling was limited and this may result in adverse medico-legal consequences for patients and clinicians.

Neonatal herpes simplex virus infection (HSV) is rare in neonates, with an estimated global incidence of 10 per 100,000 live births. Neonatal HSV is challenging to diagnose due to often vague signs and symptoms. Untreated, the mortality of some HSV subtypes exceeds 80%. Overtesting and overtreatment can result in prolonged hospitalizations and expose neonates to medication toxicity. In contrast, prompt evaluation and use of empiric antiviral therapy before the results of definitive testing can improve outcomes for infants with HSV. A wide degree of practice variation exists with respect to testing and treatment for neonatal HSV, and more research is required to safely risk-stratify this population. This review presents the epidemiology, risk factors, presenting features, and emergency department management of neonatal HSV infection.

Background: Amenamevir (AMNV) is a helicase-primase inhibitor with antiviral activity against herpesviruses [herpes simplex viruses (HSV)-1 and -2, and varicella-zoster virus], which are associated with the development of acute herpetic pain (AHP) and postherpetic neuralgia. However, the inhibitory effects of helicase-primase inhibitors on AHP and postherpetic neuralgia remain incompletely understood., Objective: In this study, we investigated the effects of AMNV on AHP and postherpetic pain (PHP) in HSV-1-infected mice accompanied by zosteriform-like skin lesions., Methods: HSV-1 was percutaneously infected on the femoral region of mice. AMNV was orally administered twice a day for 5 days. Pain-related response in the hind paw was evaluated using a paintbrush. The infiltration of inflammatory cells in dorsal root ganglion (DRG) and spinal cord (SC) was evaluated by hematoxylin and eosin staining. The viral load in DRG and the expression of pain-related genes in SC were measured by real-time PCR., Results: Pain response was begun to be observed from day 3 post-infection (pi) in HSV-1-infected mice. AMNV administered repeatedly from day 3 pi or day 4 pi, but not day 5 pi, showed an inhibitory effect on the development of AHP and the transition to PHP. Repeated AMNV administration inhibited inflammatory cell infiltration and increases in the viral load and the expression of pain-related genes (ATF-3, TNF-α, COX-2)., Conclusion: These results demonstrate that AMNV potently suppresses the development of AHP and the transition to PHP as a consequence of decreased viral load in DRG and reduced expression of pain-related genes in SC., Competing Interests: Declaration of Competing Interest The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication. This study was designed and funded by Maruho Co., Ltd., (Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.)

Background: Lesions of herpes labialis are caused by the herpes simplex virus type 1 and cause pain and aesthetic compromise. It is characterized by the formation of small vesicles that coalesce and rupture forming extremely painful ulcers, that evolve to crusts, dry desquamations until their complete remission. Currently the treatment of these lesions is done with acyclovir. Although it diminishes the symptomatology, it causes viral resistance and does not prevent the recurrence of the lesions. It is known that antimicrobial photodynamic therapy (aPDT) has numerous advantages, among them: the reduction of the time of remission, and does not cause resistance. This protocol will determine the effectiveness of PDT in lesions of herpes labialis., Materials and Methods: A total of 30 patients with herpes labialis in the prodromal stage of vesicles, ulcers, and crusts will be selected to participate in the study and randomized into 2 groups: G1 control and G2 experimental. After signing Research Ethics Committee and TA, patients in group G1 will undergo the standard gold treatment for herpes labialis with acyclovir and simulated PDT treatment. Patients in the experimental G2 group will be treated simulating the gold standard treatment of herpes labialis (placebo) and PDT. In all patients, saliva samples will be collected for analysis of cytokines, and will be performed exfoliative cytology in the lesions. The pain will be assessed through a pain scale and a questionnaire of quality of life related to oral health (OHIP-14) will be given to them. Patients will continue to be followed up after 7 days, 1 month, 3 months, and 6 months; if there is a recurrence of the lesion, they will contact the researchers.Clinical registration: clinicaltrials.gov - NCT04037475. Registered on July 2019.

Herpes simplex virus (HSV) can affect the central nervous system causing meningitis, encephalitis and, rarely, acute retinal necrosis. We present a case of a 46-year-old man, previously healthy complaining of a 5-day persistent headache and sudden loss of vision of his left eye that progressed to the right. We started ceftriaxone, methylprednisolone and acyclovir for suspected encephalitis with vasculitis. HSV-1 was identified in vitreous and aqueous humour. Therapy with acyclovir was maintained and two intravitreous boluses of foscarnet were administered, without improvement. Usually being a benign infection, HSV can, in rare cases like this, have catastrophic effects in the optic tract., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To evaluate outcomes of patients treated with intensive intravitreal therapy and to describe the evolution of quantitative real-time polymerase chain reaction (qPCR) in patients treated for acute retinal necrosis (ARN) syndrome., Design: Retrospective observational case series., Methods: This study included 25 eyes of 24 patients with ARN who were treated and followed up in 2 departments of ophthalmology in Lyon, France. Assessed outcomes included qPCR viral load profile during treatment, number of antiviral intravitreal injections (IVT), retinal detachment rate, and best-corrected visual acuity., Results: Final visual acuity was 20/200 or less in 20% of cases; the rate of retinal detachment was 16%. Viral load kinetics changed in 3 phases: a first plateau period that was not consistent, a logarithmic decrease phase, and a negativation phase. Mean decay of the logarithm of the viral load was estimated at 0.076 per day; mean time of negativation was 56.1 days. Median IVT number was 9 (range, 0-28). Ten patients were treated with injections until the viral load was undetectable. Resistance to acyclovir was observed in a patient with a prolonged initial plateau of the viral load., Conclusions: Numerous and prolonged IVTs, used as adjunctive therapy, could improve the prognosis of treated patients by decreasing the risk of retinal detachment and improving visual acuity. QPCR enables monitoring of the response to treatment and can provide evidence for resistance to antiviral treatment by enabling the detection of cases with a prolonged initial plateau of viral load., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Classically, Sanger sequencing is considered the gold standard for detection of HSV drug resistance mutations (DRMs). As a complementary method, ultra-deep sequencing (UDS) has an improved ability to detect minor variants and mixed populations. The aim of this work was to apply UDS performed on MiSeq ® Illumina platform to the detection of HSV DRMs and to the evaluation of the subpopulation diversity in clinical samples in comparison with Sanger sequencing. A total of 59 HSV-positive clinical samples (31 HSV-1 and 28 HSV-2) recovered from 50 patients mainly immunocompromised (70%) were retrospectively analyzed. Remarkably, UDS analysis revealed significant differences of relative abundance according to the type of DRMs within TK and Pol: natural polymorphisms and amino acid changes associated with resistance to antivirals were identified as high-abundant mutations (>96%), whereas TK frameshifts conferring resistance to ACV were systematically detected at lower abundance (≈80%). This work also revealed that UDS can detect low-frequency DRMs and provides extensive information on viral population composition., (Copyright © 2019 Elsevier B.V. All rights reserved.)

We report here a case of an immunocompetent patient suffering from recurrent epithelial herpetic keratitis associated with the emergence of antiviral resistance. Indeed, the not previously described amino acid change L340R within herpes simplex virus thymidine kinase, was shown to confer acyclovir-resistance by recombinant phenotyping using bacmid technology., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Herpes simplex virus (HSV) infections can cause considerable morbidity. Currently, nucleoside analogues such as acyclovir are widely used for treatment. However, HSV infections resistant to these drugs are a clinical problem among immunocompromised patients. To provide more efficient therapy and to counteract resistance, a different class of antiviral compounds has been developed. Pritelivir, a helicase primase inhibitor, represents a promising candidate for improved therapy. Here, we established an HSV-1 infection model on microneedle-pretreated human skin ex vivo. We identified HSV-1-specific histological changes (e.g., cytopathic effects, multinucleated giant cells), down-regulation of nectin-1, nuclear translocation of NF-κB (p65), interferon regulatory factor 3 (IRF3), and signaling of the IFN-inducible protein MxA. Accordingly, this model was used to test the potency of pritelivir compared with the standard drug acyclovir. We discovered that both drugs had a comparable efficacy for inhibiting HSV-1 replication, suggesting that pritelivir could be an alternative therapeutic agent for patients infected with acyclovir-resistant strains. To our knowledge, we present a previously unreported ex vivo HSV-1 infection model with abdominal human skin to test antiviral drugs, thus bridging the gap between in vitro and in vivo drug screening and providing a valuable preclinical platform for HSV research., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)

Resistant herpes simplex virus type 1 (HSV-1) infection is sometimes fatal for immunocompromised patients. Here, we report 10-year-old girl receiving hematopoietic stem cell transplantation developed refractory HSV-1 infection, which was persisted to intermittent acyclovir (ACV) or foscarnet (FOS) administrations but was improved by continuous ACV administration. The isolates from the lesion were identified with low susceptibilities to ACV and FOS by plaque reduction assay due to DNA pol gene mutation. Continuous ACV administration overcomes the efficacy of intermittent administration and could be the best option to treat severe HSV-1 infectious patients., (Copyright © 2018 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Analysis of a genome-scale RNA interference screen of host factors affecting herpes simplex virus type 1 (HSV-1) revealed that the mineralocorticoid receptor (MR) inhibits HSV-1 replication. As a ligand-activated transcription factor the MR regulates sodium transport and blood pressure in the kidney in response to aldosterone, but roles have recently been elucidated for the MR in other cellular processes. Here, we show that the MR and other members of the mineralocorticoid signalling pathway including HSP90 and FKBP4, possess anti-viral activity against HSV-1 independent of their effect on sodium transport, as shown by sodium channel inhibitors. Expression of the MR is upregulated upon infection in an interferon (IFN) and viral transcriptional activator VP16-dependent fashion. Furthermore, the MR and VP16, together with the cellular co-activator Oct-1, transactivate the hormone response element (HRE) present in the MR promoter and those of its transcriptional targets. As the MR induces IFN expression, our data suggests the MR is involved in a positive feedback loop that controls HSV-1 infection.

Several cases of herpes simplex encephalitis (HSE) caused by acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) have been reported. Amino acid substitutions of R41H, Q125H, and A156V in the viral thymidine kinase (vTK) gene have been reported to confer ACV resistance. Recombinant HSV-1 clones, containing each amino acid substitution in the vTK gene, were generated using the bacterial artificial chromosome system. A recombinant HSV-1 with the Q125H substitution showed ACV resistance while the R41H or A156V substitutions were ACV-sensitive. Furthermore, the Q125H recombinant HSV-1 was less virulent than the repaired virus, but it maintained neurovirulence in mice at relatively high levels. Substitution of Q125H, which was detected in the neonatal HSE patient, conferred ACV resistance, but the substitutions of R41H and A156V, which were detected in immunocompetent adult HSE patients, did not. This suggests that HSE caused by ACV-resistant HSV-1 might be a very rare event to occur during the course of ACV treatment in immunocompetent patients. Showing resistance to ACV treatment does not always indicate emergence of ACV-resistant HSV-1 in HSE patients.

Background: Genital herpes is an important cofactor for acquisition of human immunodeficiency virus (HIV) infection, and effective prophylaxis is a helpful strategy to halt both HIV and herpes simplex virus (HSV) transmission. The antiretroviral agent tenofovir, formulated as a vaginal microbicide gel, was shown to reduce the risk of HIV and HSV type 2 (HSV-2) acquisition., Methods: HSV type 1 (HSV-1) and HSV-2 mutants were selected for resistance to tenofovir and PMEO-DAPy (6-phosphonylmethoxyethoxy-2,4-diaminopyrimidine, an acyclic nucleoside phosphonate with dual anti-HSV and anti-HIV activity) by stepwise dose escalation. Several plaque-purified viruses were characterized phenotypically (drug resistance profiling) and genotypically (sequencing of the viral DNA polymerase gene)., Results: Tenofovir resistant and PMEO-DAPy-resistant viruses harbored specific amino acid substitutions associated with resistance not only to tenofovir and PMEO-DAPy but also to acyclovir and foscarnet. These amino acid changes (A719V, S724N, and L802F [HSV-1] and M789T and A724V [HSV-2]) were also found in clinical isolates recovered from patients refractory to acyclovir and/or foscarnet therapy or in laboratory-derived strains. A total of 10 (HSV-1) and 18 (HSV-2) well-characterized DNA polymerase mutants had decreased susceptibility to tenofovir and PMEO-DAPy., Conclusions: Tenofovir and PMEO-DAPy target the HSV DNA polymerase, and clinical isolates with DNA polymerase mutations emerging under acyclovir and/or foscarnet therapy showed cross-resistance to tenofovir and PMEO-DAPy., (© The Author(s) 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Pulmonary pathogenicity of herpes simplex virus type 1 in patients in intensive care without classic immunosuppression as well as the necessity of antiviral treatment in the case of herpes simplex virus detection in respiratory specimens in these patients is controversial. We present a case of acute respiratory distress syndrome in a patient with stable chronic lymphatic leukemia not requiring treatment, in whom we diagnosed herpes simplex virus type 1 bronchopneumonitis based on herpes simplex virus type 1 detection in bronchoalveolar lavage fluid and clinical response to antiviral treatment., Case Presentation: A 72-year-old white man presented with symptoms of lower respiratory tract infection. His medical history was significant for chronic lymphatic leukemia, which had been stable without treatment, arterial hypertension, multiple squamous cell carcinomas of the scalp, and alcohol overuse. Community-acquired pneumonia was suspected and appropriate broad-spectrum antibacterial treatment was initiated. Within a few hours, rapid respiratory deterioration led to cardiac arrest. He was successfully resuscitated, but developed acute respiratory distress syndrome. Furthermore, he remained febrile and inflammation markers remained elevated despite antibacterial treatment. Polymerase chain reaction from bronchoalveolar lavage fluid and viral culture from tracheobronchial secretions tested positive for herpes simplex virus type 1. We initiated antiviral treatment with acyclovir. Concomitantly we further escalated the antibacterial treatment, although no bacterial pathogen had been isolated at any point. Defervescence occurred rapidly and his C-reactive protein and leukocyte levels decreased. He was successfully weaned from mechanical ventilation, transferred to the ward, and eventually discharged to home., Conclusions: Herpes simplex virus should be considered a cause for lower respiratory tract infection in critically ill patients, especially in the setting of an underlying disease.

Recurrent herpes simplex keratitis (HSK) is a leading infectious cause of blindness in industrialized countries. Antiviral prophylaxis (AVP) may fail to prevent recurrence of HSK due to viral resistance, inadequate dosing, or poor patient compliance. In this prospective multicenter study, we enrolled immunocompetent patients with recurrent HSK despite AVP. Ocular samples were tested by PCR for herpes simplex virus 1 (HSV-1). HSV-1 drug resistance was assessed with a genotypic assay based on UL23 and UL30 gene sequencing. After curative full dose valacyclovir (VACV) treatment was started, peak and trough acyclovir (ACV) plasma concentrations were measured, and patient compliance to AVP was assessed with a questionnaire. The study sample was comprised of 43 patients. Six (14%) patients were positive for HSV-1 using PCR, of whom 5 (83%) harbored genotypically ACV-resistant (ACV R ) virus, due to mutations in UL23 (n = 4) or UL30 (n = 1). Disease duration was statistically significantly longer in patients with viral resistance compared to other HSK patients [35.5 ± 23.4 years (range, 6.8-68.4 years) versus 11.1 ± 12.3 years (range, 0.8-56.3 year) respectively; Mann-Whitney p = 0.01)]. While patients were treated with full dose VACV, trough ACV plasma concentrations were below the threshold for ACV sensitivity in 9.5% of cases, and compliance was poor in 5.3% of cases. To summarize, HSV-1 resistance to ACV seems to be a significant cause of failure of prophylaxis in patients with HSK and is associated with longer disease duration. Most PCR-positive samples contained genotypically ACV R virus and identification may aid in adapting treatment. Incomplete 24-h drug coverage may also explain some cases of failure of prophylaxis., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Background: Antiviral-resistant herpes simplex virus type 1 (HSV-1) has been recognized as an emerging clinical problem among patients undergoing hematopoietic stem cell transplantation (HSCT)., Methods: A prospective observational study was conducted at a hematological center over a 2-year period. Oropharyngeal swab samples were serially collected each week from 1 week before and up to 100 days after HSCT and were tested for virus isolation. The HSV-1 isolates were tested for sensitivity to acyclovir (ACV). The prognosis of patients with ACV-resistant (ACVr) HSV-1 and the genetic background of the ACVr HSV-1 isolates were assessed., Results: Herpes simplex virus type 1 was isolated in 39 of 268 (15%) HSCT patients within 100 days after transplantation. Acyclovir-resistant HSV-1 emerged in 11 of these 39 patients (28%). The 100-day death rates of HSCT patients without HSV-1 shedding, those with only ACV-sensitive HSV-1 shedding, and those with ACVr HSV-1 shedding were 31%, 39%, and 64%, respectively. Patients with HSV-1, including ACVr HSV-1, shedding showed a significantly higher mortality rate. Relapsed malignancies were a significant risk factor for the emergence of ACVr HSV-1. Acyclovir resistance was attributable to viral thymidine kinase and DNA polymerase mutations in 6 and 5 patients, respectively., Conclusions: Herpes simplex virus type 1, including ACVr HSV-1, shedding was associated with poorer outcome in HSCT patients, even if HSV disease did not always occur. Patients with relapsed malignancies were at especially high risk for the emergence of ACVr HSV-1., (© The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

This review on herpes simplex virus type I and type II (HSV-I, HSV-II) summarizes recent developments in clinical manifestations and treatment interventions for primary and recurrent orolabial and genital herpes, as well as those regarding vaccination issues. Among the clinical presentations, the relationship between pyogenic granuloma and chronic HSV-I infection; HSV-related folliculitis; verrucous HSV-I and HSV-II lesions; the role of recurrent HSV-I infection in burning mouth syndrome; HSV-I and HSV-II infection of the periareolar area; zosteriform HSV; the "knife-cut sign"; and the preferential colonization and infection of preexisting dermatoses by HSV-I or HSV-II are discussed. The usual antiviral treatment regimens for primary and recurrent orolabial and genital herpes are compared to short-term and one-day treatment options. New anti-HSV-I and anti-HSV-II agents include amenavir, pritelivir, brincidofovir, valomaciclovir, and FV-100. Therapeutic or preventive vaccination against HSV-I and HSV-II infections still remains a highly desirable treatment aim, which, unfortunately, has no clinically relevant applications to date.

Herpes labialis remains a common worldwide affliction. Recent advances in understanding the basic pathogenesis have led to new therapeutic intervention, both on-label and off-label. Aside from reducing the duration and symptomatology of acute outbreaks, another goal of treatment is to decrease the frequency of future episodes. Oral and topical acyclovir and its analogues are the mainstay of both chronic suppressive and episodic therapy. A new muco-adhesive formulation of acyclovir provides a decrease in outbreaks, probably due to a diminution of herpesvirus load in all reservoir sites. Acyclovir-resistant strains are rare in immunocompetent hosts; parenteral foscarnet and cidofovir are administered in this situation. Parenteral acyclovir is the drug of choice for eczema herpeticum, which may begin as herpes labialis in an atopic dermatitis patient. Thermotherapy may be beneficial, and a certified device to deliver heat is available outside the United States.

J Drugs Dermatol. 2017;16(3 Suppl):s49-53.

Infections with adenovirus (AdV) and herpesviruses can result in considerable morbidity and mortality in pediatric hematopoietic stem cell transplant (SCT) recipients. Herpes simplex virus (HSV) reactivations are usually prevented by acyclovir (ACV) prophylaxis, whereas cidofovir (CDV) has been used off indication to manage AdV infections. We report a child with myelodysplastic syndrome undergoing multiple SCT, who experienced HSV-1 disease including severe mucositis and herpetic whitlow, as well as high viral load AdV DNAemia. Both ACV and CDV were ineffective; however, viral loads were decreased with brincidofovir, resulting in viral clearance. A subsequent Epstein-Barr virus disease with relevant meningoencephalitis responded to rituximab., (© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objectives: In this review, we highlight and summarise the most promising extracts, fractions and pure compounds as potential anti-herpes simplex virus (HSV) agents derived from microorganisms, marine organisms, fungi, animals and plants. The role of natural products in the development of anti-HSV drugs will be discussed., Key Findings: Herpes simplex viruses (HSV-1 and -2) are common human pathogens that remain a serious threat to human health. In recent years, a great interest has been devoted to the search for integrated management of HSV infections. Acyclovir and related nucleoside analogues have been licensed for the therapy that target viral DNA polymerase. Although these drugs are currently effective against HSV infections, the intensive use of these drugs has led to the problem of drug-resistant strains. Therefore, the search for new sources to develop new antiherpetic agents has gained major priority to overcome the problem., Summary: Natural products as potential, new anti-HSV drugs provide several advantages such as reduced side effects, less resistance, low toxicity and various mechanisms of action. This paper aims to provide an overview of natural products that possess antiviral activity against HSV., (© 2015 Royal Pharmaceutical Society.)

Purpose: Aciclovir (ACV), valaciclovir (VACV) and famciclovir (FCV) are used for systemic infections caused by herpes virus. In Japan, only topical ACV is permitted for use against herpetic keratitis. We investigated the effectiveness of topical ACV, oral VACV and oral FCV on mouse epithelial herpetic keratitis., Methods: C57/BL76 mice were inoculated with HSV-1 McKrae strain in the cornea. Once infection was confirmed 4 days after inoculation, topical ACV, oral VACV and FCV were started and administered for 5 days. Control groups were given either topical or oral saline. On days 2, 4, 6 and 10 after medication started, tears, eyeballs, and trigeminal ganglia were examined using viral culture and real-time PCR., Results: Viral culture of tears detected no HSV in the topical ACV group on day 4 after administration start; with similar results for the oral VACV group on day 4; and the oral FCV group on day 6. Real-time PCR of the eyeballs showed significant decrease of HSV DNA copy number in the topical ACV group on days 4 and 6 compared to the topical saline group. Real-time PCR of the trigeminal ganglia showed significant decrease of HSV DNA copy number in the oral VACV group on days 4 and 6, and in the oral FCV group on day 6 compared to the oral saline group., Conclusion: We suggest that 5-day administration of topical ACV, oral VACV and oral FCV are effective for mouse epithelial herpetic keratitis and sufficiently decrease HSV amounts in the ocular surface and eyeballs.

Background: Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2) are important causes of acute neurologic illness. Although the role of acyclovir in treating HSV encephalitis is clear, the role of antiviral therapy in HSV meningitis remains controversial., Methods: In this retrospective observational study, we reviewed the charts of all patients with cerebrospinal fluid specimens positive for HSV-1 or HSV-2 by polymerase chain reaction between July 2000 and November 2012. Patients' charts were reviewed for demographic data, clinical presentation, treatment, and clinical outcomes., Results: Forty-two patient-episodes were clinically classified as meningitis. In 6 episodes (14.3%), patients with meningitis received no antivirals, whereas the remaining episodes were treated with an oral antiviral (n = 11 [26.2%]), combination intravenous and oral therapy (n = 22 [52.4%]), or intravenous acyclovir alone (n = 3 [7.1%]). Six patients had recurrent episodes of meningitis and all recovered without any neurologic sequelae. Neurologic outcomes were significantly improved with antiviral therapy in immunocompromised patients with herpes meningitis (P < .05), but not in the 27 patient-episodes among immunocompetent patients (P = 1.0), as no neurologic sequelae were noted in this group., Conclusions: Most patients with HSV meningitis rapidly improve, but immunocompromised hosts have more neurologic sequelae and may benefit from antiviral therapy. Our data suggest symptomatic treatment alone for immunocompetent patients with HSV meningitis, avoiding the cost and side effects of prolonged intravenous acyclovir therapy; in contrast, immunocompromised patients had improved outcomes and would therefore benefit from antiviral therapy., (© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Background: Most herpes simplex virus (HSV) isolates from treatment-naïve patients are susceptible to antivirals. However, prolonged antiviral therapy can select for drug-resistant strains, especially in immunocompromised patients. Standard phenotypic methods for antiviral resistance testing are labor and time-intense and molecular resistance determinants are insufficiently understood for routine diagnostic use of genotypic resistance testing., Objective: To enable rapid, scalable antiviral susceptibility testing and minimize viral passage, we developed a 7-day, 96-well assay for simultaneous HSV 1/2 titration and phenotypic resistance testing for acyclovir and foscarnet., Study Design: The assay was optimized and validated by testing clinical isolates and laboratory strains (n=39) with known IC50 for acyclovir (23 resistant) and foscarnet (1 resistant) based on plaque reduction or dye-uptake assays. A chemiluminescent detection reagent is used for quantification of cytopathic effect instead of plaque counting or measuring dye-uptake. Drug concentrations inhibiting 50% of chemiluminescent signal reduction (IC50) were determined concurrently at each of three virus dilutions., Results: Results agree for 92.3% (acyclovir) and 100% (foscarnet) of isolates. For all three discordant samples, results of reference testing by plaque reduction agreed with the chemiluminescent assay. Reproducibility studies showed 100% qualitative agreement and 3-37% coefficient of variation based on IC50., Conclusions: Chemiluminescence detection as a surrogate for cellular viability with an automated plate reader provides improved throughput and workflow, as well as high accuracy and reproducibility for antiviral drug susceptibility testing., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Genital herpes is a relatively common infection caused by herpes simplex virus (HSV) type one or two (HSV-1, HSV-2) respectively. It is acquired most commonly via sexual activity. More recently there has been an increase in infections due to HSV-1. Most new cases of genital HSV are not diagnosed due to HSV infections having short-lived signs and symptoms, or in many instances are asymptomatic. Hence many people infected with HSV are unaware that they have it. The risk of transmission to a partner is highest during outbreak periods, when there are visible lesions, although genital HSV can also be transmitted during asymptomatic periods. Use of condoms and antiviral medications assist in preventing transmission. Antiviral agents are effective in controlling clinical episodes, but do not eradicate infection, which remains latent for the life of a patient. Despite the surge in vaccine research, there is unfortunately no readily available preventative or therapeutic vaccine for HSV to date., (Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.)

Background and Objective: The relevance of the detection of herpes simplex virus type 1 (HSV-1) in the respiratory tract of patients in the intensive care unit (ICU) is unclear. Therefore, it is uncertain whether treatment with an antiviral agent could be beneficial for these patients., Study Design: We retrospectively reviewed the records of ICU patients with a positive HSV-1 culture in the respiratory tract or bronchoalveolar lavage (BAL) fluid. We evaluated whether acyclovir treatment (n=106) could have a beneficial effect on mortality as compared with the standard treatment (n=106)., Results: Acyclovir treatment was positively linked to in-hospital and ICU-mortality reduction. This favourable influence remained present after correcting for possible confounders and using propensity-adjusted and propensity-matched cohorts: with an odds ratio in the treated group of 3.19 (95% CI 1.79-5.69, p=0.001) for ICU survival and of 3.55 (95% CI 2.16-5.85, p<0.001) for in-hospital survival. The subgroup with HSV-1 detected in the BAL-fluid is the sole contributor to this difference. In the BAL-fluid detected group, 48% (n=10) of non-treated patients died in the ICU, versus 21% (n=6) in the acyclovir-treated group (p=0.033), occurring despite an even longer duration of ventilation or ICU stay., Conclusions: These data highlight the hypothesis that it might be worthwhile to consider treatment of HSV-1 in ICU patients depending on the type of respiratory sample in which the virus is detected. These results warrant a prospective trial to prove causality., (Copyright © 2014 Elsevier B.V. All rights reserved.)

We investigated thymidine kinase (tk) mutants isolated during multiple episodes of recurrent bilateral acyclovir resistant herpes simplex keratitis in an immunocompetent patient. From one eye, we found a single guanine insertion, previously shown to greatly reduce TK expression, and from the other, a previously unidentified substitution, which genetic experiments confirmed confers drug resistance. The substitution, although distant from substrate binding sites, reduced thymidine phosphorylation 10-20-fold, and acyclovir phosphorylation >100-fold. This phenotype should permit reactivation from latency to cause recurrent disease. The results may have implications for the prevalence and prevention of acyclovir resistance in patients with herpes simplex keratitis.

Fifty-nine US isolates of HSV-1 and HSV-2 obtained between 1998 and 2004 were tested for sensitivity to the helicase-primase inhibitor, pritelivir (AIC316, BAY 57-1293) by plaque-reduction assay. All isolates, which were collected prior to any clinical use of primase-helicase inhibitors, were sensitive and showed mean EC50 values of 0.026 and 0.029μM for HSV-1 and HSV-2, respectively. Furthermore, several laboratory-selected acyclovir-resistant HSV mutants were also sensitive to pritelivir. These data provide a baseline for HSV sensitivity to pritelivir in general population before it is introduced and broadly used to treat HSV infection. The data also validate pritelivir as an appropriate therapy for nucleoside-resistant HSV infections., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Herpes simplex virus (HSV) resistance to antivirals constitutes a therapeutic challenge, especially among immunocompromised patients. This observational survey on HSV resistance to antivirals was conducted retrospectively over a 4-year period (2008-2012). A total of 211 HSV-positive clinical samples (94 HSV-1 and 117 HSV-2) recovered from 139 patients (11 immunocompetent patients, 85 immunocompromised patients, and 43 patients with unknown immune status) with suspected HSV drug-resistance were analyzed for acyclovir and foscarnet susceptibility. Antiviral resistance testing consisted in a two-step procedure including a first-step genotypic assay, based on UL23 (thymidine kinase, TK) and UL30 (Pol) gene sequencing, and a second-step phenotypic assay (i.e., plaque reduction assay) performed when unpreviously described mutations were detected. As a whole, susceptibility and resistance to antivirals were evidenced for 58 (30.7%) and 86 (45.5%) HSV, respectively, whereas antiviral profile remained undetermined for 45 (23.8%) HSV. The prevalence of drug resistance was significantly higher among HSV-2 isolates than among HSV-1 isolates (53.8% vs. 34.9%; p=0.012). The majority (i.e., 79.7%) of cases of ACV resistance conferred by TK mutations resulted from UL23 gene frameshift reading. Apart from the changes surely related to natural polymorphism or drug-resistance, 91 unpreviously reported mutations were identified in TK and Pol, including 51 potential natural polymorphisms, 22 mutations likely conferring resistance to antivirals, and 18 mutations of unclear significance., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Eleven strains of acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) were generated from HSV-1 clinical isolates by exposure to ACV. Genotype of the thymidine kinase (TK) and DNA polymerase (pol) genes from these mutants were further analyzed. Genotypic analysis revealed four non-synonymous mutations in TK gene associated with gene polymorphism and two to three non-synonymous mutations in DNA pol gene. Seven and six strains contained at least one resistance-associated mutation at TK and DNA pol gene, respectively. Resistance-associated mutations within the TK gene consisted of 64% of non-synonymous frameshift mutations within the homopolymer region of G's and C's, and 36% of non-synonymous nucleotide substitutions of the conserved gene region (C336Y, R51W and R222H), nucleotide that produced stop codon (L288Stop) and two amino acid substitutions outside the conserved region (E39G & L208F). There were 10 non-synonymous amino acid substitutions located outside the conserved region with the unclear significance to confer resistance observed. Resistance-associated mutations in DNA pol gene include insertion of G at the homopolymer region of G's (794-797) and amino acid substitutions inside (V621S) or outside (H1228D) the conserved region. In silico analysis of the mutated TK (C336Y, R51W and L208F), and DNA pol (V621S and H1228D) suggested structural changes that might alter the stability of these proteins. However, there were several mutations with unclear significance to confer ACV-resistance identified, especially mutations outside the conserved region., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Herpes simplex virus type 1 (HSV-1) is a leading cause of corneal blindness. Acyclovir (ACV) constitutes the standard treatment of HSV infections including herpetic keratitis (HK). HSV resistance to ACV is mainly described in immunocompromised patients. We describe two cases of ACV-resistant corneal HSV-1 in immunocompetent individuals with recurrent HK., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Purpose of Review: To summarize the articles published in 2012 pertaining to the clinical presentation, diagnosis, and treatment of herpetic keratitis, with specific attention to pediatric population., Recent Findings: Liu et al. confirm prior literature that herpetic keratitis has higher recurrence rate in children than adults. Recurrences are more likely to occur as stromal disease. Vision loss in children is from corneal scarring leading to deprivation and/or refractive amblyopia. Acyclovir is safe and well tolerated as a treatment in pediatric population, and preferable to difficult and toxic eye-drop regimens.Immunochromatographic assay is an effective diagnostic tool to confirm diagnosis of herpes simplex virus-1 (HSV) in corneal scrapings with high specificity but poorer sensitivity.Real time PCR can be employed to follow changes in HSV viral load in patients where resistance is suspected., Summary: Delays in treatment related to misdiagnosis, as well as resistance to current antiviral therapeutics, can lead to visually devastating corneal opacification. In the pediatric population, already at risk for amblyopia, this can be especially damaging. Children are unique with regards to the way in which they manifest herpetic keratitis, making rapid diagnosis and treatment even more challenging.

Background: Acyclovir (ACV) is the antiviral drug of choice to treat patients with herpes simplex virus type 1 (HSV-1) uveitis. The prevalence of intra-ocular ACV-resistant (ACV(R)) HSV-1 in herpetic uveitis is unknown and may have clinical consequences. In addition to its predictive value on ACV susceptibility, the polymorphic HSV-1 thymidine kinase (TK) gene facilitates differentiation between HSV-1 strains., Objectives: The objective of this study was to determine the genetic composition and ACV susceptibility of the causative virus in intra-ocular fluid samples (IOF) of HSV-1 uveitis patients., Study Design: The intra-ocular HSV-1 pool from 11 HSV-1 uveitis patients was determined by sequencing IOF-derived viral TK genes. The ACV susceptibility profile of the cloned intra-ocular TK variants was defined by mass spectrometry. In addition, the ganciclovir (GCV) susceptibility of the ACV(R) HSV-1 TK variants was defined., Results: Intra-ocular fluid samples of HSV-1 uveitis patients contain HSV-1 quasispecies, principally consisting of one major and multiple genetically related minor patient-specific TK variants. Four of 10 patients analyzed had an intra-ocular ACV(R) HSV-1 of which 3 were cross-resistant to GCV. The ACV(R) profile of intra-ocular HSV-1 did not correlate with symptomatic ACV treatment., Conclusions: Affected eyes of HSV-1 uveitis patients are commonly infected with a patient-specific HSV-1 quasispecies, including one major and multiple genetically related minor variants. A relatively high prevalence of intra-ocular ACV(R) HSV-1, mainly ACV/GCV cross-resistant viruses, was detected in HSV-1 uveitis patients., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Cidofovir is a deoxycytidine monophosphate analog with broad spectrum activity against various deoxyribonucleic acid viruses. Cidofovir is marketed as an injectable for intravenous use; however, there is a topical cidofovir formulation utilized for viral dermatologic infections. Here, we present a case of a successful clearance of a perianal acyclovir resistant and foscarnet refractory herpes simplex virus (HSV1) ulcer in a 34 year-old woman who had undergone allogeneic hematopoietic stem cell transplantation. After 1 week of therapy with cidofovir gel, the patient's ulcer was clinically improved, and the lesion was negative for herpes simplex virus transcripts by real-time polymerase chain reaction testing. The wound remained herpes simplex virus negative by real-time polymerase chain reaction on repeat testing 1 week later. Based on this and other reports in HIV/AIDS patients, we believe that cidofovir gel has utility in the management of cutaneous, acyclovir-resistant HSV infections.

We present an unreported coexistence: eczema herpeticum (EH) with histopathological findings of herpetic folliculitis (HF) after allogeneic bone marrow transplantation (BMT). A patient with atopic dermatitis (AD) underwent allogeneic BMT for idiopathic acquired aplastic anemia. She had been receiving cyclosporine (150 mg/12 h) and acyclovir (400 mg/12 h) for 6 months. A facial rash was observed, composed of monotonous erythematous, umbilicated papulo-vesicles and papulo-crusts <4 mm in size. The histopathological study showed herpetic cytopathic changes within the epidermis that extended into the hair follicle epithelium. Interestingly, microscopic HF has not previously been associated with post-transplant patients or EH. However, it is reasonable to hypothesize that the coexistence of these herpes simplex virus-related events may be underreported in the literature. Although further studies are necessary, we suggest that the prophylactic antiviral dose after BMT be enhanced in patients with underlying dermatologic diseases, especially in those with AD., (© 2013 John Wiley & Sons A/S.)

The authors present the first reported case of herpes simplex encephalitis (HSE) precipitated by trigeminal nerve microvascular decompression (MVD). The presentation of this specific case together with the pathogenesis and management of HSE are discussed, with a relevant literature review. This 29-year-old woman with treatment-resistant trigeminal neuralgia underwent a successful elective MVD of the right trigeminal nerve. She was discharged but was readmitted 1 week postoperatively with clinical signs and symptoms of meningitis. A CSF sample was obtained through lumbar puncture before she was treated initially with ceftriaxone. The polymerase chain reaction test of CSF was later positive for herpes simplex virus Type 1, at which point the patient was switched to a 2-week course of intravenous acyclovir before being discharged. Although this disease is rare, to avoid a delay in antiviral treatment the authors suggest that HSE should be considered in any patient presenting with a meningoencephalitic picture following MVD.

A viral etiology of sudden hearing loss has been hypothesized by many authors. HSV1 neurotropism and its involvement in sudden hearing loss has implicated HSV1 as one of the most accredited etiological agents. A non-invasive method such as the titration of HSV1-specific IgA was evaluated to determine the role of HSV1 as a possible cause sudden hearing loss. A prospective study was carried out by titration of serum IgA to HSV1 in 93 patients and in a control group of 50 healthy subjects and 35 subjects suffering from recent herpes labialis reactivation. Statistical analysis of the results disclosed that IgA titers to HSV1 higher than 1:80 are suggestive for the association of HSV1 infection and sudden hearing loss. Moreover, acyclovir therapy was effective in 81% of patients who showed high specific IgA titers. Overall, the titration of specific serum IgA to HSV1 can be a useful tool to determine the viral etiology of certain cases of sudden hearing loss. This method is simple to perform and minimally invasive. It can lead to a rapid presumptive diagnosis and to prompt specific therapy, reducing the need for corticosteroids.

Acyclovir (ACV)-resistant (ACV(r)) mutants were generated from plaque-purified ACV-sensitive herpes simplex virus type 1 (HSV-1) by culturing the virus in Vero cells in the presence of 2-amino-7-(1,3-dihydroxy-2-propoxymethyl) purine (S2242). Three DNA polymerase (DNApol)-associated ACV(r) HSV-1 generated under ACV selection in a previous study (Suzutani, T., Ishioka, K., De Clercq, E., et al., Antimicrob. Agents Chemother., 47, 1707-1713, 2003) were also included. The sensitivity of the mutants to other antivirals and their neurovirulence were determined. The treatment efficacy of ACV and ganciclovir (GCV) against ACV(r) HSV-1 infections was evaluated in mice. Amino acid substitutions were demonstrated in conserved regions II and III in DNApol in 5 of the 6 mutants, while the other substitution was located in non-conserved regions. DNApol-associated ACV(r) clones showed cross-resistance to foscarnet, penciclovir, and vidarabine but were sensitive or hypersensitive to GCV, brivudin, sorivudine, and spongothymidine. The ACV(r) clone with an N815S mutation in DNApol showed similar neurovirulence to that of the parent virus; however, those with other mutations showed attenuation. GCV was effective in the treatment of the ACV(r) clone with similar virulence to that of parent HSV-1, while ACV was less effective in mice. These results indicate the importance of the characterization of HSV-1 isolates for the proper treatment of HSV-1 infections exhibiting ACV-resistance.

A neonate with herpes simplex virus 1 encephalitis was treated with intravenous acyclovir. During the course of therapy, the infection became intractable to the treatment and a mutation in the viral thymidine kinase gene (nucleotide G375T, amino acid Q125H) developed. This mutation was demonstrated in vitro to confer acyclovir resistance.

The physicochemical properties of the optimized microemulsion and the permeating ability of oxyresveratrol in microemulsion were evaluated, and the efficacy of oxyresveratrol microemulsion in cutaneous herpes simplex virus type 1 (HSV-1) infection in mice was examined. The optimized microemulsion was composed of 10% w/w of isopropyl myristate, 35% w/w of Tween 80, 35% w/w of isopropyl alcohol, and 20% w/w of water. The mean particle diameter was 9.67 ± 0.58 nm, and the solubility of oxyresveratrol in the microemulsion was 196.34 ± 0.80 mg/ml. After accelerated and long-term stability testing, the microemulsion base and oxyresveratrol-loaded microemulsion were stable. The cumulative amount of oxyresveratrol permeating through shed snake skin from microemulsion at 6 h was 93.04 times compared to that of oxyresveratrol from Vaseline, determined at 20% w/w concentration. In cutaneous HSV-1 infection in mice, oxyresveratrol microemulsion at 20%, 25%, and 30% w/w, topically applied five times daily for 7 days after infection, was significantly effective in delaying the development of skin lesions and protecting from death (p < 0.05) compared with the untreated control. Oxyresveratrol microemulsion at 25% and 30% w/w was significantly more effective than that of 30% w/w of oxyresveratrol in Vaseline (p < 0.05) and was as effective as 5% w/w of acyclovir cream, topically applied five times daily (p > 0.05). These results demonstrated that topical oxyresveratrol microemulsion at 20-30% w/w was suitable for cutaneous HSV-1 mouse infection.