A controlled trial comparing foscarnet with vidarabine for acyclovir-resistant mucocutaneous herpes simplex in the acquired immunodeficiency syndrome. The AIDS Clinical Trials Group

Successful treatment of acyclovir-resistant herpes simplex virus infection with amenamevir in a patient who received umbilical cord blood transplantation for T-cell prolymphocytic leukemia

A 34-year-old woman received umbilical cord blood transplantation for refractory T-cell prolymphocytic leukemia after salvage therapy with alemtuzumab. She developed right angular cheilitis on the 46th day after transplantation, which worsened after receiving systemic steroid therapy for extensive chronic graft versus host disease. The treatment dosage of acyclovir (ACV), ganciclovir, and vidarabine ointment was not effective due to ACV-resistant mutations of the herpes simplex virus type 1 (HSV-1) in the thymidine kinase domain. Foscarnet is expected to be effective against ACV-resistant HSV-1 infection. However, it could not be used because the patient developed renal dysfunction. Several viral thymidine kinase mutations related to ACV resistance were found in the patient's sample. Nevertheless, amenamevir, a helicase-primase complex inhibitor, was effective in our patient who was significantly immunocompromised after allogeneic hematopoietic stem cell transplantation (allo-HSCT). ACV-resistant HSV infection after allo-HSCT is an rare but important complication in the era of low-dose long-term ACV prophylaxis. To date, there is no established treatment against ACV-resistant HSV infection. This case report showed that amenamevir could be a promising treatment option for ACV-resistant HSV infection in patients with renal failure after allo-HSCT.

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

Herpes Simplex Virus (HSV) type 1 (HSV-1) and type 2 (HSV-2) are among the most common human viral pathogens, affecting several billion people worldwide. Although in healthy patients clinical signs and symptoms of HSV infection are usually mild and self-limiting, HSV-infections in immunocompromised patients are frequently more aggressive, persistent, and even life-threatening. Acyclovir and its derivatives are the gold standard antiviral drugs for the prevention and treatment of HSV infections. Although the development of acyclovir resistance is a rather uncommon condition, it may be associated with serious complications, especially in immunocompromised patients. In this review, we aim to address the problem of drug resistant HSV infection and discuss the available alternative therapeutic interventions. All relative studies concerning alternative treatment modalities of acyclovir resistant HSV infection published in PubMed between 1989 to 2022 were reviewed. Long-term treatment and prophylaxis with antiviral agents predisposes to drug resistance, especially in immunocompromised patients. Cidofovir and foscarnet could serve as alternative treatments in these cases. Although rare, acyclovir resistance may be associated with severe complications. Hopefully, in the future, novel antiviral drugs and vaccines will be available in order to avoid the existing drug resistance.

Physicochemical Characteristics of Antimicrobials and Practical Recommendations for Intravenous Administration: A Systematic Review

Most antimicrobial drugs need an intravenous (IV) administration to achieve maximum efficacy against target pathogens. IV administration is related to complications, such as tissue infiltration and thrombo-phlebitis. This systematic review aims to provide practical recommendations about diluent, pH, osmolarity, dosage, infusion rate, vesicant properties, and phlebitis rate of the most commonly used antimicrobial drugs evaluated in randomized controlled studies (RCT) till 31 March 2023. The authors searched for available IV antimicrobial drugs in RCT in PUBMED EMBASE®, EBSCO® CINAHL®, and the Cochrane Controlled Clinical trials. Drugs' chemical features were searched online, in drug data sheets, and in scientific papers, establishing that the drugs with a pH of <5 or >9, osmolarity >600 mOsm/L, high incidence of phlebitis reported in the literature, and vesicant drugs need the adoption of utmost caution during administration. We evaluated 931 papers; 232 studies were included. A total of 82 antimicrobials were identified. Regarding antibiotics, 37 reach the "caution" criterion, as well as seven antivirals, 10 antifungals, and three antiprotozoals. In this subgroup of antimicrobials, the correct vascular access device (VAD) selection is essential to avoid complications due to the administration through a peripheral vein. Knowing the physicochemical characteristics of antimicrobials is crucial to improve the patient's safety significantly, thus avoiding administration errors and local side effects.

Salvage Treatment of Refractory HSV Oral Lesions with Pritelivir in Allogeneic Hematopoietic Cell Transplant Recipients

We present two allogeneic hematopoietic cell transplantation recipients (HCTr) treated with pritelivir for acyclovir-resistant/refractory (r/r) HSV infection based on the expanded access program of the pritelivir manufacturer. Outpatient treatment with pritelivir was administered, with partial response by week 1 of treatment and complete response by week 4 of treatment in both patients. No adverse events were noted. Pritelivir appears to be an effective and safe option for the management of acyclovir-r/r HSV infections in highly immunocompromised patients in an outpatient setting.

Vulvar pseudotumoral acyclovir-resistant herpes in an HIV-negative, non-immunosuppressed patient: A therapeutic challenge

Background

Vulvar pseudotumoral herpes infections have been reported in HIV-positive patients. A 32-year-old HIV-negative woman presented with a 6-month history of a vulvar pseudotumor that had been unresponsive to oral acyclovir and valacyclovir, as well as topical imiquimod.

Objective

This study aimed to evaluate the therapeutic efficacy of a multidrug regimen for vulvar pseudotumor herpes infection in an HIV-negative patient.

Methods

Histology revealed multinucleated giant cells, consistent with a herpes infection. The patient's herpes simplex virus type 2 was resistant to acyclovir. Immunomodulatory agents (thalidomide and topical imiquimod) were started.

Results

The lesion enlarged after 6 weeks of treatment. Topical cidofovir 1% gel was added. There was gradual decrease in the pseudotumor size. After 7 months, the Pseudotumor had resolved.

Conclusion

This is the first reported case of vulvar pseudotumoral herpes in an immunocompetent, HIV-negative patient. Oral thalidomide, in association with topical imiquimod and topical cidofovir, was effective in treating acyclovir-resistant pseudotumoral herpes of the vulva.

Pathophysiology of Drug-Induced Hypomagnesaemia

Magnesium (Mg²⁺) is the second most abundant intracellular and fourth extracellular cation found in the body and is involved in a wide range of functions in the human cell and human physiology. Its role in most of the enzyme processes (ATP-ases)-stabilisation of nucleic acids (DNA, RNA), regulation of calcium and potassium ion channels, proliferation, glucose metabolism and apoptosis-make it one of the most important cations in the cell. Three pathogenetic mechanisms are mainly implicated in the development of hypomagnesaemia: reduced food intake, decreased intestinal absorption and increased renal excretion of Mg²⁺. This review presents the function of Mg²⁺, how it is handled in the kidney and the drugs that cause hypomagnesaemia. The frequency and the number of drugs like diuretics and proton-pump inhibitors (PPIs) that are used daily in medical practice are discussed in order to prevent and treat adverse effects by providing an insight into Mg²⁺ homeostasis.

Antiviral susceptibility of recombinant Herpes simplex virus 1 strains with specific polymerase amino acid changes

Acyclovir (ACV) and penciclovir and their prodrugs are recommended for therapy or prophylaxis of Herpes simplex virus 1 (HSV-1) infections. Their administration, however, can lead to the emergence of resistant strains with altered viral thymidine kinase (TK) function, especially in immunocompromised patients. Furthermore, amino acid (aa) changes of the viral deoxyribonucleic acid polymerase (POL) may contribute to resistance to the aforementioned nucleoside analogues. Given this, treatment with foscarnet (FOS) or cidofovir (CDV) may represent an important alternative. Both drugs directly affect POL activity. Several aa changes of POL, such as L49I, E70K, L359I, E421V, P829S, T1121M, and M1226I, have been observed in ACV-resistant clinical strains which also carried relevant aa changes in their TK. Their contribution to ACV, FOS, and CDV resistance is not fully understood. In this study, these seven aa changes with unknown significance for ACV, FOS and CDV resistance were introduced separately into the POL of a recombinant HSV-1 strain rHSV-1(17+)Lox, equipped with or without information for expression of green fluorescent protein (GFP). The GFP-expressing variants were tested for susceptibility to ACV, FOS and CDV. An rHSV-1(17+)Lox GFP strain with the S724N change conferring resistance to ACV and FOS was generated and included as a control. Only the S724N change was confirmed to induce ACV and FOS resistance, whereas the other changes did not contribute to resistance. The underlying nucleotide substitutions of the POL gene should be therefore considered as natural polymorphism. These data will improve sequence-based prediction of antiviral susceptibility.

Sexually Transmitted Infections Treatment Guidelines, 2021

These guidelines for the treatment of persons who have or are at risk for sexually transmitted infections (STIs) were updated by CDC after consultation with professionals knowledgeable in the field of STIs who met in Atlanta, Georgia, June 11-14, 2019. The information in this report updates the 2015 guidelines. These guidelines discuss 1) updated recommendations for treatment of Neisseria gonorrhoeae, Chlamydia trachomatis, and Trichomonas vaginalis; 2) addition of metronidazole to the recommended treatment regimen for pelvic inflammatory disease; 3) alternative treatment options for bacterial vaginosis; 4) management of Mycoplasma genitalium; 5) human papillomavirus vaccine recommendations and counseling messages; 6) expanded risk factors for syphilis testing among pregnant women; 7) one-time testing for hepatitis C infection; 8) evaluation of men who have sex with men after sexual assault; and 9) two-step testing for serologic diagnosis of genital herpes simplex virus. Physicians and other health care providers can use these guidelines to assist in prevention and treatment of STIs.

A review: Mechanism of action of antiviral drugs

Antiviral drugs are a class of medicines particularly used for the treatment of viral infections. Drugs that combat viral infections are called antiviral drugs. Viruses are among the major pathogenic agents that cause number of serious diseases in humans, animals and plants. Viruses cause many diseases in humans, from self resolving diseases to acute fatal diseases. Developing strategies for the antiviral drugs are focused on two different approaches: Targeting the viruses themselves or the host cell factors. Antiviral drugs that directly target the viruses include the inhibitors of virus attachment, inhibitors of virus entry, uncoating inhibitors, polymerase inhibitors, protease inhibitors, inhibitors of nucleoside and nucleotide reverse transcriptase and the inhibitors of integrase. The inhibitors of protease (ritonavir, atazanavir and darunavir), viral DNA polymerase (acyclovir, tenofovir, valganciclovir and valacyclovir) and of integrase (raltegravir) are listed among the Top 200 Drugs by sales during 2010s. Still no effective antiviral drugs are available for many viral infections. Though, there are a couple of drugs for herpesviruses, many for influenza and some new antiviral drugs for treating hepatitis C infection and HIV. Action mechanism of antiviral drugs consists of its transformation to triphosphate following the viral DNA synthesis inhibition. An analysis of the action mechanism of known antiviral drugs concluded that they can increase the cell’s resistance to a virus (interferons), suppress the virus adsorption in the cell or its diffusion into the cell and its deproteinisation process in the cell (amantadine) along with antimetabolites that causes the inhibition of nucleic acids synthesis. This review will address currently used antiviral drugs, mechanism of action and antiviral agents reported against COVID-19.

Phenotypic and Genotypic Testing of HSV-1 and HSV-2 Resistance to Antivirals

Resistance testing of antivirals to herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) can be done by phenotypic and genotypic methods. The determination of a resistant phenotype is based on the calculation of inhibitory concentrations for the antiviral drug, which should be tested. The main advantage of this resistance test is a clear interpretation of laboratory findings, but the method is time-consuming and a considerable experience is required by handling infectious virus. Genotypic resistance testing is based on the detection of resistance-related mutations in viral genes encoding the thymidine kinase and DNA polymerase, which need to be amplified and sequenced. This approach has the advantage of being faster, but only frameshift mutations, stops of translation, and amino acid substitutions described in the literature can be interpreted without doubt. By contrast, numerous novel amino acid substitutions are diagnostically less conclusive.

Highly Effective and Safe Polymeric Inhibitors of Herpes Simplex Virus in Vitro and in Vivo

A series of poly(ethylene glycol)-block-poly(3-(methacryloylamino)propyl trimethylammonium chloride) (PEG-b-PMAPTAC) water-soluble block copolymers consisting of PEG and PMPTAC were obtained by reversible addition-fragmentation chain-transfer (RAFT) polymerization and demonstrated to function as highly effective herpes simplex virus type 1 (HSV-1) inhibitors as shown by in vitro tests (Vero E6 cells) and in vivo experiments (mouse model). Half-maximal inhibitory concentration (IC₅₀) values were determined by quantitative polymerase chain reaction to be 0.36 ± 0.08 μg/mL for the most effective polymer PEG₄₅-b-PMAPTAC₅₂ and 0.84 ± 1.24 μg/mL for the less effective one, PEG₄₅-b-PMAPTAC₇₄. The study performed on the mouse model showed that the polymers protect mice from lethal infection. The polymers are not toxic to the primary human skin fibroblast cells up to the concentration of 100 μg/mL and to the Vero E6 cells up to 500 μg/mL. No systemic or topical toxicity was observed in vivo, even with mice treated with concentrated formulation (100 mg/mL). The mechanistic studies indicated that polymers interacted with the cell and blocked the formation of the entry/fusion complex. Physicochemical and biological properties of PEG_x-b-PMAPTAC_y make them promising drug candidates.

Herpes simplex virus infections in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HSV in the pre- and post-transplant period. A majority of transplant recipients are seropositive for HSV-1 or 2. Compared with immunocompetent persons, SOT recipients shed HSV more frequently, have more severe clinical manifestations, and are slower to respond to therapy. Most HSV infection is diagnosed on clinical grounds, but patients may present with atypical lesions and/or other clinical manifestations. Acquisition from the donor is rare. Polymerase chain reaction is the preferred diagnostic test unless culture is needed for resistance testing. For limited mucocutaneous lesions, oral therapy can be used; however, in severe, disseminated, visceral or CNS involvement, acyclovir doses of up to 10 mg/kg every 8 hours intravenously should be initiated. Acyclovir-resistant HSV is less common in SOT patients than in HSCT and can be treated with foscarnet, though other novel therapies are currently under investigation. HSV-specific prophylaxis should be considered for all HSV-1 and HSV-2-seropositive organ recipients who are not receiving antiviral medication for CMV prevention that has activity against HSV.

"For your eyes only": ophthalmic complications following lung transplantation

Ophthalmic complications in the lung transplant population are a little-known entity. It includes a spectrum of diseases ranging from infections such as cytomegalovirus (CMV) retinitis, herpetic keratitis, Pseudallescheria boydii to non-infectious complications such as posterior subcapsular cataracts (PSCs), cyclosporine retinopathy, and post-transplant lymphoproliferative disorder (PTLD). These diseases can be attributed to high levels of immunosuppression, advanced age, and drug-specific side effects. Underlying comorbidities such as diabetes mellitus may also play a role in the pathogenesis. Patients can present with varied symptoms such as blurry vision, floaters or eye pain. Prompt diagnosis often requires a high index of suspicion. With increasing numbers of transplants being performed worldwide, it is imperative for the pulmonologist and transplant physician to recognize these often subtle symptoms. Any visual symptom should trigger an ophthalmological evaluation in order to manage these complications; some of which pose the risk of systemic dissemination and significant morbidity. The following article provides an in-depth review of the common presenting symptoms, treatments and recent advances related to common ophthalmic complications following lung transplantation. While this article focuses on the lung transplant sub-population, the authors would like to point out that some of these complications are shared by other solid-organ transplants as well, by virtue of their shared immunosuppressive therapies.

Relevance of non-synonymous thymidine kinase mutations for antiviral resistance of recombinant herpes simplex virus type 2 strains

Therapy or prophylaxis of herpes simplex virus type 2 (HSV-2) infections with the nucleoside analog aciclovir (ACV) can lead to the emergence of drug-resistant HSV-2 strains, particularly in immunocompromised patients. In this context, multiple amino acid (aa) changes can accumulate in the ACV-converting viral thymidine kinase (TK) which hampers sequence-based diagnostics significantly. In this study, the so far unknown or still doubted relevance of several individual aa changes for drug resistance in HSV-2 was clarified. For this purpose, ten recombinant fluorescent HSV-2 strains differing in the respective aa within their TK were constructed using the bacterial artificial chromosome (BAC) pHSV2(MS)Lox. Similar TK expression levels and similar replication behavior patterns were demonstrated for the mutants as compared to the unmodified BAC-derived HSV-2 strain. Subsequently, the resulting strains were tested for their susceptibility to ACV as well as penciclovir (PCV) in parallel to a modified cytopathic effect (CPE) inhibition assay and by determining the relative fluorescence intensity (quantified using units, RFU) as a measure for the viral replication capacity. While aa changes Y53N and R221H conferred ACV resistance with cross-resistance to PCV, the aa changes G25A, G39E, T131M, Y133F, G150D, A157T, R248W, and L342W maintained a susceptible phenotype against both antivirals. The CPE inhibition assay and the measurement of relative fluorescence intensity yielded comparable results for the phenotypic testing of recombinant viruses. The latter test showed some technical advantages. In conclusion, the significance of single aa changes in HSV-2 TK on ACV/PCV resistance was clarified by the construction and phenotypic testing of recombinant viral strains. This was facilitated by the fluorescence based method.

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

Acyclovir resistance is rarely seen in herpes simplex virus (HSV) type I encephalitis. Prevalence rates vary between 0.5 % in immunocompetent patients (Christophers et al. 1998; Fife et al. 1994) and 3.5–10 % in immunocompromised patients (Stranska et al. 2005). We report a 45-year-old, immunocompetent (negative HIV antigen/antibody testing), female patient, without previous illness who developed—after a febrile prodromal stage—aphasia and psychomotor slowing. Cerebral magnetic resonance imaging (cMRI) showed right temporal and insular T2-hyperintense lesions with spreading to the contralateral temporal lobe. Cerebrospinal fluid (CSF) analysis yielded lymphocytic pleocytosis and elevated protein level. Polymerase chain reaction testing for HSV type I showed a positive result in repeat lumbar puncture. HSV type I encephalitis was diagnosed and intravenous acyclovir treatment was initiated (750 mg t.i.d.). Acyclovir treatment was intensified to 1000 mg t.i.d., due to clinical deterioration, ongoing pleocytosis and progression on cMRI 5 days after initiation of antiviral therapy. In parallel, acyclovir resistance testing showed mutation of thymidine kinase gene at position A156V prompting foscarnet therapy (60 mg t.i.d.). Patient’s condition improved dramatically over 2 weeks. Acyclovir resistance is rare but should be considered in case of clinical worsening of patient’s condition. To our knowledge, this is the first report of acyclovir resistance in HSV type I encephalitis of an immunocompetent and previously healthy patient in Austria.

Herpes Genitalis: Diagnosis, Treatment and Prevention

Herpes genitalis is caused by the herpes simplex virus type 1 or type 2 and can manifest as primary or recurrent infection. It is one of the most common sexually transmitted infections and due to associated physical and psychological morbidity it constitutes a considerable, often underestimated medical problem. In addition to providing the reader with basic knowledge of the pathogen and clinical presentation of herpes genitalis, this review article discusses important aspects of the laboratory diagnostics, antiviral therapy and prophylaxis. The article is aimed at all health-care workers managing patients with herpes genitalis and attempts to improve the often suboptimal counselling, targeted use of laboratory diagnostics, treatment and preventive measures provided to patients.

Interventions for men and women with their first episode of genital herpes

BACKGROUND

Genital herpes is incurable, and is caused by the herpes simplex virus (HSV). First-episode genital herpes is the first clinical presentation of herpes that a person experiences. Current treatment is based around viral suppression in order to decrease the length and severity of the episode.

OBJECTIVES

To determine the effectiveness and safety of the different existing treatments for first-episode genital herpes on the duration of symptoms and time to recurrence.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (from inception to April 2016), MEDLINE (from inception to April 2016), the Specialised Register of the Cochrane Sexually Transmitted Infections Review Group (from inception to April 2016), EMBASE (from inception to April 2016), PsycINFO (from inception to April 2016), CINAHL (from inception to April 2016), LILACS (from inception to April 2016), AMED (from inception to April 2016), and the Alternative Medicines Specialised Register (from inception to April 2016). We handsearched a number of relevant journals, searched reference lists of all included studies, databases of ongoing trials, and other Internet databases.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) on participants with first-episode genital herpes. We excluded vaccination trials, and trials in which the primary objective assessed a complication of HSV infection.

DATA COLLECTION AND ANALYSIS

All studies written in English were independently assessed by at least two review authors for inclusion, risk of bias for each trial, and to extract data. Studies requiring translation were assessed for inclusion, trial quality, and data extraction by external translators.

MAIN RESULTS

We included 26 trials with 2084 participants analysed. Most of the studies were conducted in the United Kingdom (UK) and United States (US), and involved men and women experiencing their first episode of genital herpes, with the exception of three studies which included only women. We rated the majority of these studies as having an unclear risk of bias; largely due to lack of information supplied in the publications, and due to the age of the trials. This review found low quality evidence from two studies of oral acyclovir, when compared to placebo, reduced the duration of symptoms in individuals undergoing their first episode of genital herpes (mean difference (MD) -3.22, 95% confidence interval (CI) -5.91 to -0.54; I(2) = 52%). In two studies (112 participants), intravenous acyclovir decreased the median number of days that patients with first-episode herpes suffered symptoms. Oral valaciclovir (converted to acyclovir) also showed a similar length of symptom duration when compared to acyclovir in two studies.There is currently no evidence that topical acyclovir reduces symptoms (MD -0.61 days, 95% CI -2.16 to 0.95; 3 RCTs, 195 participants, I(2) statistic = 56%). There is also no current evidence that the topical treatments of cicloxolone cream, carbenoxolone sodium cream, adenosine arabinoside, idoxuridine in dimethyl sulfoxide, when compared to placebo reduced the duration of symptoms in people undergoing their first episode of herpes.Two studies reported no evidence of a reduction in the number of median days to recurrence following treatment with oral acyclovir versus placebo. Adverse events were generally poorly reported by all of the included studies and we were unable to quantitatively analyse this outcome. For those taking acyclovir, there were no serious adverse events; the most common adverse events reported for oral acyclovir were coryza, dizziness, tiredness, diarrhoea and renal colic. For intravenous acyclovir these were phlebitis, nausea and abnormal liver function tests and for topical acyclovir there was pain with the topical application.Those undergoing interferon treatment had significantly more adverse events compared to those taking placebo.

AUTHORS' CONCLUSIONS

There is low quality evidence from this review that oral acyclovir reduced the duration of symptoms for genital herpes. However, there is low quality evidence which did not show that topical antivirals reduced symptom duration for patients undergoing their first episode of genital herpes. This review was limited by the inclusion of skewed data, resulting in few trials that we were able to meta-analyse.

Current Concepts for Genital Herpes Simplex Virus Infection: Diagnostics and Pathogenesis of Genital Tract Shedding

Herpes simplex virus 2 (HSV-2) is a DNA virus that is efficiently transmitted through intimate genital tract contact and causes persistent infection that cannot be eliminated. HSV-2 may cause frequent, symptomatic self-limited genital ulcers, but in most persons infection is subclinical. However, recent studies have demonstrated that the virus is frequently shed from genital surfaces even in the absence of signs or symptoms of clinical disease and that the virus can be transmitted during these periods of shedding. Furthermore, HSV-2 shedding is detected throughout the genital tract and may be associated with genital tract inflammation, which likely contributes to increased risk of HIV acquisition. This review focuses on HSV diagnostics, as well as what we have learned about the importance of frequent genital HSV shedding for (i) HSV transmission and (ii) genital tract inflammation, as well as (iii) the impact of HSV-2 infection on HIV acquisition and transmission. We conclude with discussion of future areas of research to push the field forward.

Recombinant herpes simplex virus type 1 strains with targeted mutations relevant for aciclovir susceptibility

Here, we describe a novel reliable method to assess the significance of individual mutations within the thymidine kinase (TK) gene of herpes simplex virus type 1 (HSV-1) to nucleoside analogue resistance. Eleven defined single nucleotide polymorphisms that occur in the TK gene of clinical HSV-1 isolates and a fluorescence reporter were introduced into the HSV-1 strain 17⁺ that had been cloned into a bacterial artificial chromosome. The susceptibility of these different strains to aciclovir, penciclovir, brivudin, and foscarnet was determined with a modified cytopathic effect reduction assay. The strains were also tested for their aciclovir susceptibility by measuring the relative fluorescence intensity as an indicator for HSV-1 replication and by quantifying the virus yield. Our data indicate that the amino acid substitutions R41H, R106H, A118V, L139V, K219T, S276R, L298R, S345P, and V348I represent natural polymorphisms of the TK protein, whereas G61A and P84L mediate broad cross-resistance against aciclovir, penciclovir, brivudin, and susceptibility to foscarnet. This method allows the definition of the resistance genotype of otherwise unclear mutations in the TK gene of HSV-1. Thus, it provides a scientific basis for antiviral testing in clinical isolates of patients suffering from serious diseases and will facilitate testing of new antivirals against HSV-1.

Progress in the Clinical Management of Herpesvirus Infections

Antiviral drug discovery has produced a series of drugs active against herpesviruses in vitro. Several of these are now licensed and/or have been used in clinical practice. This article reviews the mechanisms of action of acyclovir, ganciclovir, penciclovir, sorivudine and foscarnet, the development of resistance to these drugs and their pharmacokinetic and cellular toxicities. Based upon the natural histories of HSV, VZV and CMV, treatment objectives for each virus are discussed and the performance of each drug matched against these objectives. Overall, it is concluded that the perfect drug for treating herpesviruses does not exist, but that significant progress has been made towards controlling several herpesvirus diseases. It is suggested that further progress will require not just improved drug discovery programmes, but also an understanding of different pathogeneses and an appreciation by practising physicians that antiviral drugs must be given early in the infectious process to achieve the best results.

Phenotypic Resistance of Herpes Simplex Virus Type 1 Strains Selected in Vitro with Antiviral Compounds and Combinations Thereof

Several drug-resistant herpes simplex virus type 1 (HSV-1) strains were obtained under the selective pressure of various antiherpetic drugs used alone or in combination. Their susceptibility to a wide range of antiviral compounds was determined. Strains selected under the pressure of brivudin (BVDU) or 1-β-D-arabinofuranosyl-( E)-5-(2-bromovinyl)uracil (BVaraU) alone were composed of two virus populations: (1) virus resistant to BVDU and BVaraU but not to acyclovir (ACV) or ganciclovir (GCV), which is suggestive of an alteration in the thymidylate kinase activity associated with the viral thymidine kinase (TK) (responsible for the phosphorylation of BVDU-monophosphate to BVDU-diphosphate); and (2) virus resistant to BVDU, BVaraU, ACV and GCV, which is indicative of an alteration in the viral TK activity that converts BVDU, BVaraU and other nucleoside analogues such as ACV and GCV to their monophosphate derivatives. Strains resistant to TK-dependent drugs (i.e. ACV, GCV, BVDU and BVaraU) as well as double-mutant strains with decreased sensitivity to both TK-dependent compounds and the pyrophosphate analogues foscarnet (PFA) and phosphonoacetic acid (PAA) (suggestive of mutations at the level of the DNA polymerase) were recovered under the selective pressure of ACV alone or in combination with BVDU or BVaraU. Combinations of BVDU or BVaraU with PFA or PAA led to strains resistant only to BVDU and BVaraU or double-mutant strains resistant to BVDU, BVaraU and the pyrophosphate analogues, but not to strains resistant to other TK-dependent drugs. Interestingly, strains resistant to ACV, BVDU, GCV and/or the pyrophosphate analogues PFA and PAA remained sensitive to the (S)-3-hydroxy-2-phosphonylmethoxypropyl (HPMP) derivatives of cytosine (HPMPC) and adenine (HPMPA).

Differential Susceptibility of Several Drug-Resistant Strains of Herpes Simplex Virus Type 2 to Various Antiviral Compounds

Drug-resistant herpes simplex virus type 2 (HSV-2) strains were obtained under the selective pressure of acyclovir, ganciclovir, brivudin, foscamet, 2-phosphonyl-methoxyethyl (PME) derivatives of adenine (PMEA) and 2,6-diaminopurine (PMEDAP), and 3-hydroxy-2-phosphonylmethoxypropyl (HPMP) derivatives of adenine (HPMPA) and cytosine (HPMPC; cidofovir). A significant degree of cross-resistance between HPMPC and HPMPA on the one hand, and between PMEA, PMEDAP and foscarnet on the other, was noted, suggesting a different mode of interaction of the PME and HPMP derivatives at the DNA polymerase level. The results described here with HSV-2 agree with the published results for HSV-1 and human cytomegalovirus.

Optimal management of genital herpes: current perspectives

As one of the most common sexually transmitted diseases, genital herpes is a global medical problem with significant physical and psychological morbidity. Genital herpes is caused by herpes simplex virus type 1 or type 2 and can manifest as primary and/or recurrent infection. This manuscript provides an overview about the fundamental knowledge on the virus, its epidemiology, and infection. Furthermore, the current possibilities of antiviral therapeutic interventions and laboratory diagnosis of genital herpes as well as the present situation and perspectives for the treatment by novel antivirals and prevention of disease by vaccination are presented. Since the medical management of patients with genital herpes simplex virus infection is often unsatisfactory, this review aims at all physicians and health professionals who are involved in the care of patients with genital herpes. The information provided would help to improve the counseling of affected patients and to optimize the diagnosis, treatment, and prevention of this particular disease.

Mathematical Modeling Predicts that Increased HSV-2 Shedding in HIV-1 Infected Persons Is Due to Poor Immunologic Control in Ganglia and Genital Mucosa

A signature feature of HIV infection is poor control of herpes virus infections, which reactivate from latency and cause opportunistic infections. While the general mechanism underlying this observation is deficient CD4+T-cell function, it is unknown whether increased severity of herpes virus infections is due primarily to poor immune control in latent or lytic sites of infection, or whether CD4+ immunodeficiency leads to more critical downstream deficits in humoral or cell-mediated immunologic responses. Here we compare genital shedding patterns of herpes simplex virus-2 (HSV-2) in 98 HIV infected and 98 HIV uninfected men matched on length of infection, HSV-1 serostatus and nationality. We demonstrate that high copy HSV-2 shedding is more frequent in HIV positive men, particularly in participants with CD4+ T-cell count <200/μL. Genital shedding is more frequent due to higher rate of shedding episodes, as well as a higher proportion of prolonged shedding episodes. Peak episode viral load was not found to differ between HIV infected and uninfected participants regardless of CD4+ T-cell count. We simulate a mathematical model which recapitulates these findings and identifies that rate of HSV-2 release from neural tissue increases, duration of mucosal cytolytic immune protection decreases, and cell-free viral lifespan increases in HIV infected participants. These results suggest that increased HSV-2 shedding in HIV infected persons may be caused by impaired immune function in both latent and lytic tissue compartments, with deficits in clearance of HSV-2 infected cells and extracellular virus.

Varicella-zoster virus infections - antiviral therapy and diagnosis

Varicella-zoster virus is an important human pathogen that causes varicella after primary infection and zoster after recurrence. Following primary infection, the virus remains latently for life in dorsal root and cranial nerve ganglia. Varicella and zoster are worldwide widespread diseases and may be associated with significant complications. This manuscript presents a short overview about the fundamental knowledge including the most important clinical signs, the capabilities for antiviral treatment and the spectrum of methods for laboratory diagnosis.

Diagnosis, antiviral therapy, and prophylaxis of varicella-zoster virus infections

Varicella-zoster virus (VZV), an important member of the Herpesviridae family, is the etiological agent of varicella as primary infection and zoster as recurrence. An outstanding feature is the lifelong viral latency in dorsal root and cranial nerve ganglia. Both varicella and zoster are worldwide widespread diseases that may be associated with significant complications. However, there is a broad spectrum of laboratory methods to diagnose VZV infections. In contrast to many other viral infections, antiviral treatment of VZV infections and their prevention by vaccination or passive immunoprophylaxis are well established in medical practice. The present manuscript provides an overview about the basic knowledge of VZV infections, their laboratory diagnosis, antiviral therapy, and the prevention procedures, especially in Germany.

In search for effective and definitive treatment of herpes simplex virus type 1 (HSV-1) infections

Herpes Simplex Virus type 1 (HSV-1) is a nuclear replicating enveloped virus.

Sequence Analysis of Herpes Simplex Virus 1 Thymidine Kinase and DNA Polymerase Genes from over 300 Clinical Isolates from 1973 to 2014 Finds Novel Mutations That May Be Relevant for Development of Antiviral Resistance

A total of 302 clinical herpes simplex virus 1 (HSV-1) strains, collected over 4 decades from 1973 to 2014, were characterized retrospectively for drug resistance. All HSV-1 isolates were analyzed genotypically for nonsynonymous mutations in the thymidine kinase (TK) and DNA polymerase (Pol) genes. The resistance phenotype against acyclovir (ACV) and/or foscarnet (FOS) was examined in the case of novel, unclear, or resistance-related mutations. Twenty-six novel natural polymorphisms could be detected in the TK gene and 69 in the DNA Pol gene. Furthermore, three novel resistance-associated mutations (two in the TK gene and one in the DNA Pol gene) were analyzed, and eight known but hitherto unclear amino acid substitutions (two encoded in TK and six in the DNA Pol gene) could be clarified. Between 1973 and 2014, the distribution of amino acid changes related to the natural gene polymorphisms of TK and DNA Pol remained largely stable. Resistance to ACV was confirmed phenotypically for 16 isolates, and resistance to ACV plus FOS was confirmed for 1 isolate. Acyclovir-resistant strains were observed from the year 1995 onwards, predominantly in immunosuppressed patients, especially those with stem cell transplantation, and the number of ACV-resistant strains increased during the last 2 decades. The data confirm the strong genetic variability among HIV-1 isolates, which is more pronounced in the DNA Pol gene than in the TK gene, and will facilitate considerably the rapid genotypic diagnosis of HSV-1 resistance.

2014 UK national guideline for the management of anogenital herpes

These guidelines concern the management of anogenital herpes simplex virus infections in adults and give advice on diagnosis, management, and counselling of patients. This guideline replaces the 2007 BASHH herpes guidelines and includes new sections on herpes proctitis, key points to cover with patients regarding transmission and removal of advice on the management of HSV in pregnancy which now has a separate joint BASHH/RCOG guideline.

Docking and antiherpetic activity of 2-aminobenzo[de]-isoquinoline-1,3-diones

As part of our search for new compounds having antiviral effects, the prepared 2-aminonaphthalimide series was examined for its activity against the herpes simplex viruses HSV-1 and HSV-2. This represents the first study of the antiviral effects of this class of compounds. The new series of 2-amino-1H-benzo[de]isoquinoline-1,3-diones was examined against HSV-1 and HSV-2 using a cytopathic effect inhibition assay. In terms of effective concentration (EC50), furaldehyde, thiophene aldehyde and allyl isothiocyanide derivatives 14‒16 showed potent activity against HSV-1 (EC50 = 19.6, 16.2 and 17.8 μg/mL), compared to acyclovir as a reference drug (EC50 = 1.8 μg/mL). Moreover, 14 and 15 were found to exhibit valuable activity against HSV-2. Many of the tested compounds demonstrated weak to moderate EC50 values relative to their inactive parent compound (2-amino-1H-benzo[de]isoquinoline-1,3-dione), while compounds 7, 9, 13, 14, 15, 16, 21 and 22 were the most active set of antiviral compounds throughout this study. The cytotoxicity (CC50), EC50, and the selectivity index (SI) values were determined. In a molecular docking study, the ligand-receptor interactions of compounds 1-24 and their parent with the HSV-1 thymidine kinase active site were investigated using the Molegro Virtual Docker (MVD) software. Based on the potent anti-HSV properties of the previous naphthalimide condensate products, further exploration of this series of 2-amino-1H-benzo[de]isoquinoline-1,3-diones is warranted.

Drug resistance of clinical varicella-zoster virus strains confirmed by recombinant thymidine kinase expression and by targeted resistance mutagenesis of a cloned wild-type isolate

In this study, approaches were developed to examine the phenotypes of nonviable clinical varicella-zoster virus (VZV) strains with amino acid substitutions in the thymidine kinase (TK) (open reading frame 36 [ORF36]) and/or DNA polymerase (Pol) (ORF28) suspected to cause resistance to antivirals. Initially, recombinant TK proteins containing amino acid substitutions described as known or suspected causes of antiviral resistance were analyzed by measuring the TK activity by applying a modified commercial enzyme immunoassay. To examine the effects of these TK and Pol substitutions on the replication of recombinant virus strains, the method of en passant mutagenesis was used. Targeted mutations within ORF36 and/or ORF28 and an autonomously expressed gene of the monomeric red fluorescent protein for plaque identification were introduced into the European wild-type VZV strain HJO. Plaque reduction assays revealed that the amino acid substitutions with unknown functions in TK, Q303stop, N334stop, A163stop, and the deletion of amino acids 7 to 74 aa (Δaa 7 to 74), were associated with resistance against acyclovir (ACV), penciclovir, or brivudine, whereas the L73I substitution and the Pol substitutions T237K and A955T revealed sensitive viral phenotypes. The results were confirmed by quantitative PCR by measuring the viral load under increasing ACV concentrations. In conclusion, analyzing the enzymatic activities of recombinant TK proteins represent a useful tool for evaluating the significance of amino acid substitutions in the antiviral resistance of clinical VZV strains. However, direct testing of replication-competent viruses by the introduction of nonsynonymous mutations in a VZV bacterial artificial chromosome using en passant mutagenesis led to reliable phenotypic characterization results.

Herpes simplex virus drug-resistance: new mutations and insights

PURPOSE OF REVIEW

Acyclovir (ACV) is the first-line treatment for the management of herpes simplex virus 1 (HSV-1) and 2 (HSV-2) diseases. Long-term administration of the drug for the treatment of chronic infections in the immunocompromised host can lead to the development of ACV-resistance. This review provides an update of the mutations linked to drug-resistance and issues to be considered in the management of HSV infections refractory to antiviral therapy.

RECENT FINDINGS

Recent data have shown that HSV drug-resistance should be taken into account not only in immunocompromised individuals but also in immunocompetent persons when HSV infections involve 'immune-privileged sites'. Thus, drug-resistance typing is recommended in cases of ACV unresponsive herpetic keratitis and herpes simplex encephalitis. Several issues regarding HSV drug-resistance were highlighted by recent studies. Phenotypic and genotypic antiviral resistance may vary not only from different compartments but also over time, highlighting the importance of characterizing longitudinal HSV isolates from all sites. Combination therapy should be considered when viruses with distinct phenotype/genotype are identified at one or at distinct body sites.

SUMMARY

Surveillance of HSV drug-resistance is highly recommended in immunocompromised patients and in immunocompetent individuals with infections implicating 'immune-privileged sites' to rationally adapt antiviral treatment.

Single nucleotide polymorphisms of thymidine kinase and DNA polymerase genes in clinical herpes simplex virus type 1 isolates associated with different resistance phenotypes

The role of mutations in the thymidine kinase (TK, UL23) and DNA polymerase (pol, UL30) genes of herpes simplex virus (HSV) for development of different resistance phenotypes has to be exactly determined before genotypic resistance testing can be implemented in patient's care. Furthermore, the occurrence of cross-resistance is of utmost clinical importance. In this study, clinical HSV-1 isolates obtained between 2004 and 2011 from 26 patients after stem cell transplantation were examined in parallel by phenotypic and genotypic resistance testing. Thirteen isolates, which were phenotypically cross-resistant to acyclovir (ACV), penciclovir (PCV) and brivudin (BVDU), exhibited consistently frameshift or non-synonymous mutations in the TK gene known to confer resistance. One of these mutations (insertion of C at the nucleotide positions 1061-1065) has not been described before. Seven strains, phenotypically resistant to ACV and PCV and, except one each, sensitive to BVDU and resistant to foscarnet (FOS), carried uniformly resistance-related substitutions in the DNA pol gene. Finally, 3 isolates, resistant to ACV, PCV and 2 out of these also resistant to BVDU, had known but also unclear substitutions in the TK and DNA pol genes, and 3 isolates were completely sensitive. In conclusion, clinical ACV-resistant HSV-1 isolates, carrying resistance-associated mutations in the TK gene, can be regarded as cross-resistant to other nucleoside analogs such as BVDU. In contrast, clinical FOS-resistant HSV-1 strains which are cross-resistant to ACV may be sensitive to BVDU. This has to be considered for drug changes in antiviral treatment in case of ACV resistance.

Long-term follow-up of HIV-infected patients once diagnosed with acyclovir-resistant herpes simplex virus infection

Acyclovir-resistant herpes simplex virus (HSV) infection is common in immunocompromised patients, but the course of such infection is little known. We describe the long-term follow-up of HIV-infected patients diagnosed once with acyclovir-resistant HSV infections. We retrospectively studied all HIV-infected patients between 2000 and 2010 diagnosed with virologically confirmed acyclovir-resistant HSV infection. Patients' socio-demographic and immunovirological characteristics were described. Response to foscarnet or cidofovir and recurrences were reported. Among 5295 HIV-infected patients, 13 (0.2%) were once diagnosed with an acyclovir-resistant HSV infection. Twelve patients were men, nine patients were of African origin. All patients reported previous acyclovir exposure and median CD4 count was 183 cells/mm(3) Ten patients presented exclusively with cutaneous lesions. Initially, 11 patients were treated with foscarnet and two with cidofovir. The median follow-up was 67 months (6-145). All patients recurred, 10 presenting at least one acyclovir-resistant HSV recurrence. The median number of acyclovir-resistant HSV recurrences per patient was 2 (0 - 5). Regarding the first and second recurrences, 7/13 (54%) and 5/11 (45%) HSV clinical isolates exhibited resistance to acyclovir, respectively. Acyclovir-resistant HSV infection prevalence was low in our cohort. The rate of acyclovir-resistant HSV episodes averaged 50% during the two first recurrences.

Advances in the management of viral infections

Viral infections are common in cancer patients. The risk and severity of infection are influenced by patient, disease, treatment, and viral factors. Severe viral infections are more likely to occur in treatment regimens that are more immunosuppressive. Historically, the most frequent severe infections have been due to herpesviruses, but more recently, other pathogens, especially community respiratory and hepatitis viruses, have received increasing attention as major viral pathogens in cancer patients. Because of the new diagnostic assays and the introduction of better therapeutic options, knowledge of viral infections is important in optimizing antineoplastic therapies.

Phenotypic and genotypic testing of HSV-1 resistance to antivirals

Resistance testing of antivirals to herpes simplex virus type 1 can be done by phenotypic and genotypic methods. The determination of a resistant phenotype is based on the calculation of inhibitory concentrations for the antiviral drug, which should be tested. The main advantage is a clear interpretation of laboratory findings, but the method is time consuming and a considerable experience is required for handling infectious virus. Genotypic resistance testing is based on the detection of resistance-related mutations in viral genes encoding the thymidine kinase and DNA polymerase by means of amplification and sequencing. This approach has the advantage of being faster, but only frameshift mutations and stops of translation can be interpreted without doubt and numerous amino acid substitutions are diagnostically less conclusive.

Glycoprotein targeted therapeutics: a new era of anti-herpes simplex virus-1 therapeutics

Herpes simplex virus type-1 (HSV-1) is among the most common human pathogens worldwide. Its entry into host cells is an intricate process that relies heavily on the ability of the viral glycoproteins to bind host cellular proteins and to efficiently mediate fusion of the virus envelope with the cell membrane. Acquisition of HSV-1 results in a lifelong latent infection. Because of the cycles of reactivation from a latent state, much emphasis has been placed on the management of infection through the use of DNA synthesis inhibitors. However, new methods are needed to provide more effective treatment at earlier phases of the viral infection and to prevent the development of drug resistance by the virus. This review outlines the infection process and the common therapeutics currently used against the fundamental stages of HSV-1 replication and fusion. The remainder of this article will focus on a new approach for HSV-1 infection control and management, the concept of glycoprotein-receptor targeting.

Varicella zoster virus (VZV) and herpes simplex virus (HSV) in solid organ transplant patients

Varicella zoster virus (VZV) and the two herpes simplex viruses (HSV) are human α-herpesviruses that establish life-long latency in neural ganglia after initial primary infection. In the solid organ transplant (SOT) population, manifestations of VZV or HSV may be seen in up to 70% of recipients if no prophylaxis is used, some of them life and organ threatening. While there are effective vaccines to prevent VZV primary infection and reactivation in immunocompetent adults, these vaccines are contraindicated after SOT because they are live-virus vaccines. For HSV, prevention has focused primarily on antiviral strategies because the immunologic correlates of protection and control are different from VZV, making vaccine development more challenging. Current antiviral therapy remains effective for the majority of clinical VZV and HSV infections.

Chronic ulcerative herpes simplex virus infection of the vulva

Herpes simplex virus infections in HIV-infected individuals can be clinically unusual and difficult to treat due to underlying problems with cell-mediated immunity and the occurrence of antiviral resistance. Additionally, partial or incomplete restoration of immune function may result in chronic ulcerations that require rotational treatments. In this report, we describe the case of a 38-year-old HIV-positive woman who developed the ulcerative form of chronic herpes simplex infection despite highly active antiretroviral therapy and valacyclovir prophylaxis. Repeated intravenous courses of foscarnet and topical cidofovir finally controlled her erosions as her cell-mediated immunity was slowly restored. This case highlights the challenges that still exist in diagnosing and managing this rare presentation of herpes simplex virus

Anti-herpes virus activities of bioactive fraction and isolated pure constituent of Mallotus peltatus: an ethnomedicine from Andaman Islands

BACKGROUND

Viral infections, particularly the infections caused by herpes simplex virus (HSV), represent one of the most serious public health concerns globally because of their devastating impact. The aim of this study was to evaluate the antiviral potential of methanolic crude extract of an ethnomedicine Mallotus peltatus, its active fraction and pure compound, against HSV-1 F and HSV-2 G.

RESULT

The cytotoxicity (CC(50), the concentration of 50% cellular toxicity), antiviral effective concentration (EC(50), the concentration required to achieve 50% protection against virus-induced cytopathic effect), plaque reduction and the selectivity index (SI, the ratio of CC(50) and EC(50)) was determined. Results showed that the crude methanolic extract of M. peltatus possessed weak anti-HSV activity. In contrast, the active fraction A and isolated ursolic acid from fraction A exhibited potent antiherpesvirus activity against both HSV-1 (EC(50)= 7.8 and 5.5 μg/ml; SI = 22.3 and 20) and HSV-2 (EC(50)= 8.2 and 5.8 μg/ml, and SI = 21.2 and 18.97). The fraction A and isolated ursolic acid (10 μg/ml) inhibited plaque formation of HSV-1 and HSV-2 at more than 80% levels, with a dose dependent antiviral activity, compared to acyclovir. The time response study revealed that the anti-HSV activity of fraction A and isolated ursolic acid is highest at 2-5 h post-infection. Moreover, the time kinetics study by indirect immunofluorescence assay showed a characteristic pattern of small foci of single fluorescent cells in fraction A- treated virus infected cells at 2 h and 4 h post-infection, suggesting drug inhibited viral dissemination. Further, the PCR study with infected cell cultures treated with fraction A and isolated ursolic acid at various time intervals, failed to show amplification at 48-72 h, like acyclovir treated HSV-infected cells. Moreover, fraction A or isolated ursolic acid showed no interaction in combination with acyclovir.

CONCLUSION

This study revealed that bioactive fraction A and isolated ursolic acid of M. peltatus has good anti-HSV activity, probably by inhibiting the early stage of multiplication (post-infection of 0-5 h), with SI value of 20, suggesting its potential use as anti-HSV agents.

Novel resistance-associated mutations of thymidine kinase and DNA polymerase genes of herpes simplex virus type 1 and type 2

BACKGROUND

Studies to verify correlations between phenotypes and genotypes of herpes simplex virus (HSV) are an important tool to establish a database of resistance-associated mutations.

METHODS

In this study, 32 acyclovir (ACV)-resistant clinical HSV-1 and 4 ACV-resistant clinical HSV-2 isolates were examined in parallel by both phenotypic and genotypic resistance testing. Additionally, five non-viable HSV-1 strains and two non-viable HSV-2 strains with clinical resistance were included in genotypic resistance analysis.

RESULTS

All ACV-resistant HSV isolates showed cross-resistance to brivudin and penciclovir, and were sensitive to foscarnet and cidofovir. Acyclovir resistance was assigned to frameshift and single non-synonymous mutations of the thymidine kinase (TK) gene in 32 out of 37 HSV-1 strains and in 4 out of 6 HSV-2 strains. In three HSV-1 isolates, there were resistance-associated amino acid substitutions of the DNA polymerase (pol). Six substitutions in the TK and two in the DNA pol gene could not be attributed without doubt to either ACV resistance or natural gene polymorphism. Altogether, 10 resistance-related mutations in the TK and 1 in the DNA pol gene have not been reported previously.

CONCLUSIONS

The novel non-synonymous mutations found in this study enrich the knowledge about the genetic alterations of TK and DNA pol genes in ACV-resistant clinical HSV strains. Together with data from the literature, the findings justify the generation of a HSV database that contains resistance mutations associated with ACV resistance phenotype.

The use of antiviral drugs during the neonatal period

Parenteral therapy of viral infections of the newborn and infant began with vidarabine (adenine arabinoside) for the treatment of neonatal herpes simplex virus (HSV) infections in the early 1980s. Acyclovir has become the treatment of choice for neonatal HSV infections and a variety of other herpesvirus infections. Ganciclovir is beneficial for the treatment of congenital cytomegalovirus (CMV) infections involving the central nervous system (CNS). This article reviews the use of acyclovir and ganciclovir in the treatment of neonatal HSV and congenital CMV infections. A brief summary precedes a detailed discussion of available established and alternative therapeutics.