Acyclovir resistance in herpes simplex virus type I encephalitis: a case report

Insights into adjunctive corticosteroid therapy in fulminant herpes simplex virus encephalitis: case analysis with contrasting outcomes

Herpes simplex virus (HSV) encephalitis, predominantly caused by HSV-1, presents with significant morbidity and mortality challenges. This research investigates the particular role of adjunctive corticosteroid therapy in fulminant HSV encephalitis through in-depth analyses of two contrasting cases. Corticosteroids show potential benefits to improve an exaggerated immune response and limit viral dissemination within the brain. Daily assessments and frequent neuroimaging, particularly using magnetic resonance imaging, aid in the management of fulminant cases. Although existing evidence relies on limited case series and retrospective comparisons, the results of the present study emphasize the necessity for large-scale controlled trials to establish definitive guidelines. The discretion of the treating neurologist governs the decision to implement corticosteroids, emphasizing the imperative need for continued research and evidence-based strategies for this challenging neurological condition.

CNS Viral Infections-What to Consider for Improving Drug Treatment: A Plea for Using Mathematical Modeling Approaches

Neurotropic viruses may cause meningitis, myelitis, encephalitis, or meningoencephalitis. These inflammatory conditions of the central nervous system (CNS) may have serious and devastating consequences if not treated adequately. In this review, we first summarize how neurotropic viruses can enter the CNS by (1) crossing the blood-brain barrier or blood-cerebrospinal fluid barrier; (2) invading the nose via the olfactory route; or (3) invading the peripheral nervous system. Neurotropic viruses may then enter the intracellular space of brain cells via endocytosis and/or membrane fusion. Antiviral drugs are currently used for different viral CNS infections, even though their use and dosing regimens within the CNS, with the exception of acyclovir, are minimally supported by clinical evidence. We therefore provide considerations to optimize drug treatment(s) for these neurotropic viruses. Antiviral drugs should cross the blood-brain barrier/blood cerebrospinal fluid barrier and pass the brain cellular membrane to inhibit these viruses inside the brain cells. Some antiviral drugs may also require intracellular conversion into their active metabolite(s). This illustrates the need to better understand these mechanisms because these processes dictate drug exposure within the CNS that ultimately determine the success of antiviral drugs for CNS infections. Finally, we discuss mathematical model-based approaches for optimizing antiviral treatments. Thereby emphasizing the potential of CNS physiologically based pharmacokinetic models because direct measurement of brain intracellular exposure in living humans faces ethical restrictions. Existing physiologically based pharmacokinetic models combined with in vitro pharmacokinetic/pharmacodynamic information can be used to predict drug exposure and evaluate efficacy of antiviral drugs within the CNS, to ultimately optimize the treatments of CNS viral infections.

Antimicrobial Potential of Natural Compounds of Zingiberaceae Plants and their Synthetic Analogues: A Scoping Review of In vitro and In silico Approaches

AIMS

There has been increased scientific interest in bioactive compounds and their synthetic derivatives to promote the development of antimicrobial agents that could be used sustainably and overcome antibiotic resistance.

METHODS

We conducted this scoping review to collect evidence related to the antimicrobial potential of diverse natural compounds from Zingiberaceae plants and their synthetic derivatives. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Extension for Scoping Reviews guidelines. The literature search was conducted using PubMed, Web of Science and Scopus electronic databases for relevant studies published from 2012 to 2023. A total of 28 scientific studies fulfilled the inclusion criteria. The authors of these studies implemented in vitro and in silico methods to examine the antimicrobial potency and underlying mechanisms of the investigated compounds.

RESULT

The evidence elucidates the antimicrobial activity of natural secondary metabolites from Zingiberaceae species and their synthetic derivatives against a broad panel of gram-positive and gram-negative bacteria, fungi and viruses.

CONCLUSION

To date, researchers have proposed the application of bioactive compounds derived from Zingiberaceae plants and their synthetic analogues as antimicrobial agents. Nevertheless, more investigations are required to ascertain their efficacy and to broaden their commercial applicability.

Antiviral treatment for acute retinal necrosis: A systematic review and meta-analysis

Acute retinal necrosis is a progressive intraocular inflammatory syndrome characterized by diffuse necrotizing retinitis that can lead to a poor visual outcome, mainly from retinal detachment. The antiviral treatment approach for acute retinal necrosis varies as there are no established guidelines. We summarize the outcomes of acute retinal necrosis with available antiviral treatments. Electronic searches were conducted in PubMed/MEDLINE, EMBASE, Scopus, and Google Scholar for interventional and observational studies. Meta-analysis was performed to evaluate the pooled proportion of the predefined selected outcomes. This study was registered in PROSPERO (CRD42022320987). Thirty-four studies with a total of 963 participants and 1,090 eyes were included in the final analysis. The estimated varicella-zoster virus and herpes simplex virus polymerase chain reaction-positive cases were 63% (95% CI: 55-71%) and 35% (95% CI: 28-42%), respectively. The 3 main antiviral treatment approaches identified were oral antivirals alone, intravenous antivirals alone, and a combination of systemic (oral or intravenous) and intravitreal antivirals. The overall pooled estimated proportions of visual acuity improvement, recurrence, and retinal detachment were 37% (95% CI: 27-47%), 14% (95% CI: 8-21%), and 43% (95% CI: 38-50%), respectively. Patients treated with systemic and intravitreal antivirals showed a trend towards better visual outcomes than those treated with systemic antivirals (oral or intravenous) alone, even though this analysis was not statistically significant (test for subgroup differences P = 0.83).

State of the Art: Acute Encephalitis

Encephalitis is a devastating neurologic disease often complicated by prolonged neurologic deficits. Best practices for the management of adult patients include universal testing for a core group of etiologies, including herpes simplex virus (HSV)-1, varicella zoster virus (VZV), enteroviruses, West Nile virus, and anti-N-methyl-D-aspartate receptor (anti-NMDAR) antibody encephalitis. Empiric acyclovir therapy should be started at presentation and in selected cases continued until a second HSV-1 polymerase chain reaction test is negative. Acyclovir dose can be increased for VZV encephalitis. Supportive care is necessary for other viral etiologies. Patients in whom no cause for encephalitis is identified represent a particular challenge. Management includes repeat brain magnetic resonance imaging, imaging for occult malignancy, and empiric immunomodulatory treatment for autoimmune conditions. Next-generation sequencing (NGS) or brain biopsy should be considered. The rapid pace of discovery regarding autoimmune encephalitis and the development of advanced molecular tests such as NGS have improved diagnosis and outcomes. Research priorities include development of novel therapeutics.

Hypericin blocks the function of HSV-1 alkaline nuclease and suppresses viral replication

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum perforatum L. has a long history in many countries of being used as a herbal medicine. It is also widely used in Chinese herbal medicine for the treatment of infections. Hypericin, a main component extracted from Hypericum perforatum L., has attracted the attention of many researchers for its remarkable antiviral, antitumor and antidepressant effects.

AIM OF THE STUDY

To find plant molecules that inhibit the alkaline nuclease (AN) of herpes simplex virus type 1 (HSV-1) and suppress viral replication.

MATERIALS AND METHODS

Bioinformatics methods were used to determine which compounds from a variety of natural compounds in our laboratory interact with AN. By this means we predicted that hypericin may interact with AN and suppress HSV-1 replication. Experiments were then carried out to verify whether hypericin inhibits the bioactivity of AN. The Pichia pastoris expression system was used to obtain recombinant AN. The exonuclease and endonuclease activity of AN treated with hypericin were tested by electrophoresis. Immunohistochemical staining of the HSV-1 nucleocapsids was used to find out whether hypericin inhibits the intracellular function of AN. Real-time PCR and western blotting analysis were performed to test viral gene expression and viral protein synthesis. The extent of viral replication inhibited by hypericin was determined by a plaque assay and a time of addition assay.

RESULTS

Recombinant AN was obtained by Pichia pastoris expression system. The exonuclease and endonuclease activity of recombinant AN were inhibited by hypericin in the electrophoresis assay. Hypericin showed no inhibitory effect on BeyoZonase™ Super Nuclease or DNase I. T5 Exonuclease activity was inhibited partially by10 μM hypericin, and was completely suppressed by 50 μM hypericin. Hind Ⅲ was inhibited by hypericin at concentrations greater than 100 μM, but EcoR I, BamH I, and Sal I were not inhibited by hypericin. HSV-1 nucleocapsids gathered in the nucleus when the viruses were treated with hypericin. Plaque formation was significantly reduced by hypericin (EC₅₀ against HSV-1 F is 2.59 ± 0.08 μM and EC₅₀ against HSV-1 SM44 is 2.94 ± 0.10 μM). UL12, ICP27, ICP8, gD, and UL53 gene expression (P < 0.01, 4.0 μM hypericin treated group vs control group) and ICP4 (P < 0.05, 6.0 μM hypericin treated group vs control group), ICP8 and gD (P < 0.05, 2.0 μM hypericin treated group vs control group) protein synthesis were inhibited by hypericin. In the time of addition assay, HSV-1 was suppressed by hypericin in the early stages of viral replication. Hypericin exhibits potent virucidal activity against HSV-1 and inhibits the adsorption and penetration of HSV-1.

CONCLUSION

Hypericin inhibits the bioactivity of AN and suppresses HSV-1 replication. The data revealed a novel mechanism of the antiherpetic effect of hypericin.

A Review of the Treatment of Herpes Simplex Virus-1 Encephalitis in Six Immunocompetent Patients

Introduction

The optimal treatment regimen for herpes simplex-1 (HSV-1) encephalitis is ill-defined. Current guidelines recommend the initiation of acyclovir in all suspected cases of encephalitis; however, there is limited research regarding the details of acyclovir treatment or the adjuvant use of corticosteroids. Specifically, there is a paucity of evidence-based guidelines detailing the optimal management of HSV-1 encephalitis in immunocompetent patients. In this study, we conducted a review of cases of immunocompetent patients with HSV-1 encephalitis to compare patterns in treatment and outcomes. 

Methods

A review of the literature was performed using PubMed using the terms herpes encephalitis, HSV, herpes zoster, and immunocompetent to identify cases of HSV-1 encephalitis in immunocompetent patients. The results were screened for cases describing the treatment regimen of HSV-1 encephalitis-positive, immunocompetent patients. 

Results

Six cases were identified. All six patients were treated with acyclovir with one patient receiving adjuvant corticosteroid therapy. Additionally, three patients were found to have acyclovir resistance and were transitioned to foscarnet. Eventually, one patient expired, two patients recovered with chronic morbidities of varying severity, and three patients made a full recovery. 

Discussion

Inconsistencies in the patient's disease course, therapeutic regimen, and comorbidities could all play a role in the varying case outcomes. While the optimal timing and composition of therapies in HSV-1 encephalitis in immunocompetent patients are still unclear, it seems the timely administration of antiviral treatment remains essential. Further research is needed to optimize HSV-1 encephalitis therapeutic regimens and improve patient outcomes. 

Antiviral Potential of Naphthoquinones Derivatives Encapsulated within Liposomes

HSV infections, both type 1 and type 2, are among the most widespread viral diseases affecting people of all ages. Their symptoms could be mild, with cold sores up to 10 days of infection, blindness and encephalitis caused by HSV-1 affecting immunocompetent and immunosuppressed individuals. The severe effects derive from co-evolution with the host, resulting in immune evasion mechanisms, including latency and growing resistance to acyclovir and derivatives. An efficient alternative to controlling the spreading of HSV mutations is the exploitation of new drugs, and the possibility of enhancing their delivery through the encapsulation of drugs into nanoparticles, such as liposomes. In this work, liposomes were loaded with a series of 2-aminomethyl- 3-hydroxy-1,4-naphthoquinones derivatives with n-butyl (compound 1), benzyl (compound 2) and nitrobenzene (compound 3) substituents in the primary amine of naphthoquinone. They were previously identified to have significant inhibitory activity against HSV-1. All of the aminomethylnaphthoquinones derivatives encapsulated in the phosphatidylcholine liposomes were able to control the early and late phases of HSV-1 replication, especially those substituted with the benzyl (compound 2) and nitrobenzene (compound 3), which yields selective index values that are almost nine times more efficient than acyclovir. The growing interest of the industry in topical administration against HSV supports our choice of liposome as a drug carrier of aminomethylnaphthoquinones derivatives for formulations of in vivo pre-clinical assays.

Herpes Labialis: A New Possibility for Topical Treatment with Well-Elucidated Drugs

Mucocutaneous infections caused by Herpes simplex virus (HSV-1 and HSV-2) are characterized by the appearance of vesicles that cause pain and embarrassment to the carrier. The standard treatment is based on the use of antivirals in gels or ointments, however, relapses are common. Local anesthetics decrease the pain caused by the lesion, in addition to showing antiviral properties. Semi-solid form facilitates application and its transformation into a thin film favors the maintenance of the formulation in place, with a more discreet final aspect. The objective of this study was to develop and evaluate formulations containing anesthetics for the treatment of cold sores. For this purpose, two semi-solid film-forming formulations were developed and evaluated, containing HPMC K100, lidocaine (LIDO) and prilocaine (PRILO) combined with adjuvants, in the presence (F1T) or not (F1) of the absorption promoter Transcutol®. The mixture of PRILO and LIDO resulted in the formation of a eutectic mixture (EM), essential for penetration of drugs into the skin. The quantification of drugs was performed by HPLC (High Performance Liquid Chromatography), and Transcutol® did not influence the release of drugs from the formulation. The bioadhesiveness of the formulation was evaluate and the drugs did not impair the adhesive potential of the polymers used. The formulations were evaluated in vivo for skin irritation and did not show any negative sign on macroscopic examination. The in vivo efficacy test proved the anesthetics' ability to decrease the lesions caused by HSV-1. Thus, the proposed formulations proved to be good alternatives to the treatment of oral lesions caused by HSV-1.

Post-herpetic encephalitis cerebral abscess: Viral reactivation or latency site within central nervous system?

Herpetic encephalitis results from central nervous system invasion by herpes simplex virus. We report the case of a man who developed a cerebral abscess fifteen months after initial Herpetic encephalitis. Retrospectively, antiviral should not have been associated with antibiotics during abscess episode, as transcriptomic analysis reported no viral reactivation.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Cold atmospheric plasma as antiviral therapy - effect on human herpes simplex virus type 1

In previous studies, cold atmospheric plasma (CAP) was explored as an antibacterial and antiviral agent for the treatment of chronic wounds. The aim of the present study was to investigate whether CAP may also be suitable as an antiviral therapy against herpes simplex virus type 1 (HSV-1). HSV-1 most frequently manifests as recurrent herpes labialis, but it can also cause encephalitis, conjunctivitis or herpes neonatorum as a perinatal infection. HSV-1 encoding the reporter gene GFP was propagated. The CAP dose for HSV-1 treatment was gradually increased, ranging from 0-150 s, and aciclovir was used as a positive control. After CAP treatment, the virus suspension was applied to a standard HSV research cell line (Vero cells) and the neuroblastoma cell line SH-SY5Y as a model for neuronal infection. The results showed that plasma treatment had a negligible antiviral effect on HSV-1 in both Vero- and SH-SY5Y cells at high dose. However, when we lowered the viral load 100-fold, we observed a significantly decreased number of internalized HSV-1 genomes 3 h post-infection for CAP-treated viruses. This difference was less pronounced with respect to GFP expression levels 24 h post-infection, which was in sharp contrast to the acyclovir-treated positive control, for which the viral load was reduced from 95 to 25%. In summary, we observed a low but measurable antiviral effect of CAP on HSV-1.

Understanding and managing acute encephalitis

Encephalitis is an important cause of morbidity, mortality, and permanent neurologic sequelae  globally. Causes are diverse and include viral and non-viral infections of the brain as well as autoimmune processes. In the West, the autoimmune encephalitides are now more common than any single infectious cause, but, in Asia, infectious causes are still more common. In 2006, the World Health Organization coined the term "acute encephalitis syndrome", which simply means acute onset of fever with convulsions or altered consciousness or both. In 2013, the International Encephalitis Consortium set criteria for diagnosis of encephalitis on basis of clinical and laboratory features. The most important infectious cause in the West is herpes simplex virus, but globally Japanese encephalitis (JE) remains the single largest cause. Etiologic diagnosis is difficult because of the large number of agents that can cause encephalitis. Also, the responsible virus may be detectable only in the brain and is either absent or transiently found in blood or cerebrospinal fluid (CSF). Virological diagnosis is complex, expensive, and time-consuming. Different centres could make their own algorithms for investigation in accordance with the local etiologic scenarios. Magnetic resonance imaging (MRI) and electroencephalography are specific for few agents. Clinically, severity may vary widely. A severe case may manifest with fever, convulsions, coma, neurologic deficits, and death. Autoimmune encephalitis (AIE)  includes two major categories: (i) classic paraneoplastic limbic encephalitis (LE) with autoantibodies against intracellular neuronal antigens (Eg: Hu and Ma2) and (ii) new-type AIE with autoantibodies to neuronal surface or synaptic antigens (Eg: anti-N-methyl-D-aspartate receptor). AIE has prominent psychiatric manifestations: psychosis, aggression, mutism, memory loss, euphoria, or fear. Seizures, cognitive decline, coma, and abnormal movements are common. Symptoms may fluctuate rapidly. Treatment is largely supportive. Specific treatment is available for herpesvirus group and non-viral infections. Various forms of immunotherapy are used for AIE.

Efficacy of pritelivir and acyclovir in the treatment of herpes simplex virus infections in a mouse model of herpes simplex encephalitis

Pritelivir, a helicase-primase inhibitor, has excellent in vitro and in vivo activity against human herpes simplex virus (HSV). Mice lethally infected with HSV type 1 or 2, including acyclovir-resistant strains, were treated 72 h after infection for 7 days with pritelivir or acyclovir. Both drugs were administered orally twice daily either alone or in combination. Dosages of pritelivir from 0.3 to 30 mg/kg reduced mortality (P < 0.001) against HSV-1, E-377. With an acyclovir resistant HSV-1, 11360, pritelivir at 1 and 3 mg/kg increased survival (P < 0.005). With HSV-2, MS infected mice, all dosages higher than the 0.3 mg/kg dose of pritelivir were effective (P < 0.005). For acyclovir resistant HSV-2, strain 12247, pritelivir dosages of 1-3 mg/kg significantly improved survival (P < 0.0001). Combination therapies of pritelivir at 0.1 or 0.3 mg/kg/dose with acyclovir (10 mg/kg/dose) were protective (P < 0.0001) when compared to the vehicle treated group against HSV-2, strain MS (in line with previous data using HSV-1). An increased mean days to death (P < 0.05) was also observed and was indicative of a potential synergy. Pharmacokinetic studies were performed to determine pritelivir concentrations and a dose dependent relationship was found in both plasma and brain samples regardless of infection status or time of initiation of dosing. In summary, pritelivir was shown to be active when treatment was delayed to 72 h post viral inoculation and appeared to synergistically inhibit mortality in this model in combination with acyclovir. We conclude pritelivir has potent and resistance-breaking antiviral efficacy with potential for the treatment of potentially life-threatening HSV type 1 and 2 infections, including herpes simplex encephalitis.