Foscarnet therapy for severe acyclovir-resistant herpes simplex virus type-2 infections in patients with the acquired immunodeficiency syndrome (AIDS). An uncontrolled trial

Ellagitannins as synergists of ACV on the replication of ACV-resistant strains of HSV 1 and 2

The plant-derived polyphenolic compounds castalagin, vescalagin and grandinin (C-glucosidic ellagitannins containing nonahydroxyterphenoyl) manifested a strong inhibitory effect on the replication of acyclovir-resistant strains of herpes simplex viruses (HSV) type 1 and 2 in MDBK cells in focus forming units (i.e., microscopically registered microplaques) reduction assay and in two variants of cytopathic effect inhibition test. The effect on the acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) strain was markedly higher compared to that on the ACV-resistant herpes simplex virus type 2 (HSV-2). The three compounds showed comparable levels of antiviral activity against ACV-resistant HSV strains, in contrast with previous results where castalagin exerted the highest degree of activity against wild type HSV strains (Vilhelmova et al., 2011). Combinations of ellagitannins and ACV were tested on the ACV-resistant strains of both HSV-1 and 2 and produced synergistic effects that were revealed by applying the three-dimensional approach of Prichard and Shipman (1990). The ellagitannin(s)-ACV combination applied against ACV-resistant HSV-1 produced a much stronger synergistic effect compared to the effect observed against ACV-resistant HSV-2. The study of the effects of the combination ellagitannin(s)-ACF on intact cell monolayers did not show any toxicity resulting from interaction between the two substances. Altogether, the results obtained in this study demonstrate the highly promising potential of these plant polyphenols as antiherpetic agents.

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.

Expression of herpes simplex virus type 1 recombinant thymidine kinase and its application to a rapid antiviral sensitivity assay

Antiviral-resistant herpesvirus infection has become a great concern for immunocompromised patients. Herpes simplex virus type 1 (HSV-1) infections are treated with viral thymidine kinase (vTK)-associated drugs such as acyclovir (ACV), and most ACV-resistance (ACV(r)) is due to mutations in the vTK. The standard drug sensitivity test is usually carried out by the plaque reduction assay-based method, which requires over 10 days. To shorten the time required, a novel system was developed by the concept, in which 293T cells transiently expressing recombinant vTK derived from the test sample by transfection of the cells with an expression vector were infected with vTK-deficient and ACV(r) HSV-1 (TAR), and then cultured in a maintenance medium with or without designated concentrations of ACV, ganciclovir (GCV) and brivudine (BVdU). The replication of TAR was strongly inhibited by ACV, GCV and BVdU in 293T cells expressing recombinant vTK of the ACV-sensitive HSV-1, whereas replication was not or slightly inhibited in cells expressing the recombinant vTK of highly resistant or intermediately resistant HSV-1, respectively. An inverse correlation was demonstrated in the 50% effective concentrations (EC(50)s) and inhibitory effects of these compounds on the replication of TAR among ACV(s) and ACV(r) HSV-1 clones. These results indicate that the EC(50)s of the vTK-associated drugs including ACV can be assumed by measuring the inhibitory effect of drugs in 293T cells expressing recombinant vTK of the target virus. The newly developed antiviral sensitivity assay system for HSV-1 makes it possible to estimate EC(50) for vTK-associated drugs, when whole vTK gene is available for use by gene amplification directly from lesion's samples or from virus isolates.

Resistance of herpes simplex viruses to nucleoside analogues: mechanisms, prevalence, and management

Herpes simplex viruses (HSV) type 1 and type 2 are responsible for recurrent orolabial and genital infections. The standard therapy for the management of HSV infections includes acyclovir (ACV) and penciclovir (PCV) with their respective prodrugs valacyclovir and famciclovir. These compounds are phosphorylated by the viral thymidine kinase (TK) and then by cellular kinases. The triphosphate forms selectively inhibit the viral DNA polymerase (DNA pol) activity. Drug-resistant HSV isolates are frequently recovered from immunocompromised patients but rarely found in immunocompetent subjects. The gold standard phenotypic method for evaluating the susceptibility of HSV isolates to antiviral drugs is the plaque reduction assay. Plaque autoradiography allows the associated phenotype to be distinguished (TK-wild-type, TK-negative, TK-low-producer, or TK-altered viruses or mixtures of wild-type and mutant viruses). Genotypic characterization of drug-resistant isolates can reveal mutations located in the viral TK and/or in the DNA pol genes. Recombinant HSV mutants can be generated to analyze the contribution of each specific mutation with regard to the drug resistance phenotype. Most ACV-resistant mutants exhibit some reduction in their capacity to establish latency and to reactivate, as well as in their degree of neurovirulence in animal models of HSV infection. For instance, TK-negative HSV mutants establish latency with a lower efficiency than wild-type strains and reactivate poorly. DNA pol HSV mutants exhibit different degrees of attenuation of neurovirulence. The management of ACV- or PCV-resistant HSV infections includes the use of the pyrophosphate analogue foscarnet and the nucleotide analogue cidofovir. There is a need to develop new antiherpetic compounds with different mechanisms of action.

Genotypic characterization of the DNA polymerase and sensitivity to antiviral compounds of foscarnet-resistant herpes simplex virus type 1 (HSV-1) derived from a foscarnet-sensitive HSV-1 strain

Foscarnet is widely used for the treatment of acyclovir-resistant herpesvirus infections, and foscarnet-resistant herpesvirus infections are a serious concern in immunocompromised patients. Twenty-seven single-plaque isolates of herpes simplex virus type 1 (HSV-1) resistant to foscarnet were selected from foscarnet- and acyclovir-sensitive HSV-1 strain TAS by exposure to foscarnet, and the DNA polymerase genes were analyzed. The sensitivities of these mutants to foscarnet, cidofovir, S2242, acyclovir, ganciclovir, and penciclovir were determined. A single amino acid substitution, double amino acid substitutions, and a combination of a single amino acid substitution with a deletion or insertion of amino acid residues in the viral DNA polymerase were demonstrated in 21, 4, and 2 isolates, respectively. Of the 27 isolates, an amino acid substitution of serine for asparagine at amino acid position 724 in the DNA polymerase (724 S-N) was detected in 8 isolates. An amino acid substitution in conserved region II was demonstrated in these eight isolates as well as four other isolates. The mutation in the DNA polymerase responsible for resistance to foscarnet was located between the pre-IV region and conserved region V, especially within conserved region II. All the isolates were sensitive or hypersensitive to cidofovir and ganciclovir. Seven, 5, and 15 of the 27 isolates were also sensitive to S2242, acyclovir, and penciclovir, respectively. Thus, most of the foscarnet-resistant HSV-1 isolates were sensitive or hypersensitive to cidofovir and ganciclovir.

Evaluation of Some Pyrazoloquinolines as Inhibitors of Herpes Simplex Virus Type 1 Replication

Three structurally related aminopyrazoloquinoline derivatives were evaluated for their antiviral activity against Herpes Simplex virus type 1. These compounds were examined for their in vitro antiviral activity by two different bioassays, namely; crystal violet staining and tetrazolium dye (MTS) measurement. The antiviral role of these compounds was confirmed by enumerating the infectious particles with plaque assay. The acute toxicity values of the biologically active compounds were determined prior to their screening as antiviral agents.

Resistance of Herpes Simplex Virus Infections to Nucleoside Analogues in HIV‐Infected Patients

Antiviral treatment of herpes simplex virus (HSV) infections with nucleoside analogues has been well established for >2 decades, but isolation of drug-resistant HSV from immunocompetent patients has remained infrequent (0.1%-0.7% of isolates) during this period. Even when drug-resistant HSV is isolated from an immunocompetent patient, this virus, with rare exceptions, is cleared normally without adverse clinical outcome. Although drug-resistant HSV is more commonly isolated from immunocompromised patients (4%-7% of isolates) and is more likely to be clinically significant, the prevalence of drug-resistant HSV even among these patients, has been stable over the past 2 decades. Despite this stable prevalence, disease due to drug-resistant HSV remains an important problem for many immunocompromised patients, including those with HIV infection. This article reviews the prevalence, pathogenesis, and implications of drug-resistant HSV infections in HIV-infected patients.

[Acyclovir-resistant herpes exulcerans et persistens. Type II]

Immunocompromised patients are developing in an increasing frequency acyclovir-resistant herpes simplex infections. Different treatment options need to be evaluated considering the possible side effects in regard to the patients' immunocompromised status. A 73-year-old woman with B-cell lymphatic leukemia with a secondary antibody deficiency syndrome and anemia suffered for one year with perianal ulcerations caused by acyclovir-resistant herpes simplex infection Type II. Based on previous reports about successful treatment of acyclovir-resistant herpes simplex infections with foscarnet, cidofovir or vidarabine and considering the different side effects of these drugs as well as the underlying diseases of the patient, we treated her with foscarnet intravenously. After 3 months the ulcers showed a nearly complete remission.

Management of acyclovir-resistant herpes simplex virus

In immunocompetent patients, HSV is controlled rapidly by the human host's immune system, and recurrent lesions are small and short lived. When treated with antiviral agents, these patients rarely develop resistance to these drugs. In contrast immunocompromised patients might not be able to control HSV infection. Thus, frequent and severe reactivations are often seen and might lead to fatal herpetic encephalitis or disseminated HSV infection. Treatment in these patients is limited because immunocompromised hosts often develop severe herpes disease refractory to antiviral drug therapy. It is therefore imperative that physicians develop regimens to deal with both receptive and refractory HSV disease. The following treatment protocol (modified from Balfour and colleagues) might serve as a guide until further investigation of new drugs is performed. In all patients standard oral ACV therapy should be initiated at a dose of 200 mg orally, five times a day for the first 3 to 5 days. Prior to treatment, cultures the lesions should be obtained to verify HSV etiology. If the response is poor, the dose of oral ACV should be increased to 800 mg five times a day. If no response seen after 5 to 7 days, it is unlikely that the lesion will respond to intravenous ACV (or chemically and structurally related drugs such as VCV or famciclovir), so an alternative regimen must be assigned. First, repeat cultures for vital, fungal, and bacterial pathogens must be performed. In addition, ACV susceptibility studies should be ordered, if available. If the mucocutaneous lesion is accessible for topical treatment, TFT (as ophthalmic solution) should be applied to the area three to four times a day until the lesion is completely healed. If the lesion is inaccessible or if the response to TFT is poor, therapy with intravenous foscarnet should be given for 10 days or until complete resolution of the lesions. The dosage of foscarnet should be 40 milligrams per kilogram three times per day or 60 milligrams per kilogram twice daily. If foscarnet fails to achieve clinical clearing, consideration should be given to use of intravenous cidofovir (or application of compounded 1% to 3% topical cidofovir ointment). Vidarabine is reserved for situations in which all of these therapies fail. If lesions reoccur in the same location following clearing, the patient should started on high-dose oral ACV (800 mg, five times daily) or intravenous foscarnet (40 mg/kg tid or 60 mg/kg bid) as soon as possible. When lesions occur in a different location, the patient should be treated initially with standard doses of oral ACV (200 mg, five times daily) and the above protocol should be followed should there be clinical failure. In the future, new treatment options for patients with documented HSV resistance will be important in reducing the clinical impact of HSV.

Herpes simplex virus resistance to acyclovir and penciclovir after two decades of antiviral therapy

Acyclovir, penciclovir, and their prodrugs have been widely used during the past two decades for the treatment of herpesvirus infections. In spite of the distribution of over 2.3 x 10(6) kg of these nucleoside analogues, the prevalence of acyclovir resistance in herpes simplex virus isolates from immunocompetent hosts has remained stable at approximately 0.3%. In immuncompromised patients, in whom the risk for developing resistance is much greater, the prevalence of resistant virus has also remained stable but at a higher level, typically 4 to 7%. These observations are examined in the light of characteristics of the virus, the drugs, and host factors.

Sodium lauryl sulfate increases the efficacy of a topical formulation of foscarnet against herpes simplex virus type 1 cutaneous lesions in mice

The influence of sodium lauryl sulfate (SLS) on the efficacies of topical gel formulations of foscarnet against herpes simplex virus type 1 (HSV-1) cutaneous infection has been evaluated in mice. A single application of the gel formulation containing 3% foscarnet given 24 h postinfection exerted only a modest effect on the development of herpetic skin lesions. Of prime interest, the addition of 5% SLS to this gel formulation markedly reduced the mean lesion score. The improved efficacy of the foscarnet formulation containing SLS could be attributed to an increased penetration of the antiviral agent into the epidermis. In vitro, SLS decreased in a concentration-dependent manner the infectivities of herpesviruses for Vero cells. SLS also inhibited the HSV-1 strain F-induced cytopathic effect. Combinations of foscarnet and SLS resulted in subsynergistic to subantagonistic effects, depending on the concentration used. Foscarnet in phosphate-buffered saline decreased in a dose-dependent manner the viability of cultured human skin fibroblasts. This toxic effect was markedly decreased when foscarnet was incorporated into the polymer matrix. The presence of SLS in the gel formulations did not alter the viabilities of these cells. The use of gel formulations containing foscarnet and SLS could represent an attractive approach to the treatment of herpetic mucocutaneous lesions, especially those caused by acyclovir-resistant strains.

A double-blind placebo-controlled crossover trial of intravenous magnesium sulfate for foscarnet-induced ionized hypocalcemia and hypomagnesemia in patients with AIDS and cytomegalovirus infection

Foscarnet (trisodium phosphonoformate hexahydrate) is an antiviral agent used to treat cytomegalovirus disease in immunocompromised patients. One common side effect is acute ionized hypocalcemia and hypomagnesemia following intravenous administration. Foscarnet-induced ionized hypomagnesemia might contribute to ionized hypocalcemia by impairing excretion of preformed parathyroid hormone (PTH) or by producing target organ resistance. Prevention of ionized hypomagnesemia following foscarnet administration could blunt the development of ionized hypocalcemia. To determine whether intravenous magnesium ameliorates the decline in ionized calcium and/or magnesium following foscarnet infusions, MgSO(4) at doses of 1, 2, and 3 g was administered in a double-blind, placebo-controlled, randomized, crossover trial to 12 patients with AIDS and cytomegalovirus disease. Overall, increasing doses of MgSO(4) reduced or eliminated foscarnet-induced acute ionized hypomagnesemia. Supplementation, however, had no discernible effect on foscarnet-induced ionized hypocalcemia despite significant increases in serum PTH levels. No dose-related, clinically significant adverse events were found, suggesting that intravenous supplementation with up to 3 g of MgSO(4) was safe in this chronically ill population. Since parenteral MgSO(4) did not alter foscarnet-induced ionized hypocalcemia or symptoms associated with foscarnet, routine intravenous supplementation for patients with normal serum magnesium levels is not recommended during treatment with foscarnet.

Efficacies of topical formulations of foscarnet and acyclovir and of 5-percent acyclovir ointment (Zovirax) in a murine model of cutaneous herpes simplex virus type 1 infection

The topical efficacies of foscarnet and acyclovir incorporated into a polyoxypropylene-polyoxyethylene polymer were evaluated and compared to that of 5% acyclovir ointment (Zovirax) by use of a murine model of cutaneous herpes simplex virus type 1 infection. All three treatments given three times daily for 4 days and initiated 24 h after infection prevented the development of the zosteriform rash in mice. The acyclovir formulation and the acyclovir ointment reduced the virus titers below detectable levels in skin samples from the majority of mice, whereas the foscarnet formulation has less of an antiviral effect. Reducing the number of treatments to a single application given 24 h postinfection resulted in a significantly higher efficacy of the formulation of acyclovir than of the acyclovir ointment. Acyclovir incorporated within the polymer was also significantly more effective than the acyclovir ointment when treatment was initiated on day 5 postinfection. The higher efficacy of the acyclovir formulation than of the acyclovir ointment is attributed to the semiviscous character of the polymer, which allows better penetration of the drug into the skin.

Oral infections and other manifestations of HIV disease

Oral lesions are important in the clinical spectrum of HIV/AIDS, arousing suspicion of acute seroconversion illness (aphthous ulceration and candidiasis), suggesting HIV infection in the undiagnosed individual (candidiasis, hairy leukoplakia, Kaposi's sarcoma, necrotizing ulcerative gingivitis), indicating clinical disease progression and predicting development of AIDS (candidiasis, hairy leukoplakia), and marking immune suppression in HIV-infected individuals (candidiasis, hairy leukoplakia, necrotizing periodontal disease, Kaposi's sarcoma, long-standing herpes infection, major aphthous ulcers). In addition, oral lesions are included in staging systems for HIV disease progression and as entry criteria or endpoints in clinical trials of antiretroviral drugs. Recognition and management of these oral conditions is important for the health and quality of life of the individual with HIV/AIDS. In keeping with this, the U.S. Department of Health Services Clinical Practice Guideline for Evaluation and Management of Early HIV Infection includes recommendations that an oral examination, emphasizing oral mucosal surfaces, be conducted by the primary care provider at each visit, a dental examination by a dentist should be done at least two times a year, and patients should be informed of the importance of oral care and educated about common HIV-related oral lesions and associated symptoms.

Treatment of mucocutaneous herpes simplex virus infections unresponsive to acyclovir with topical foscarnet cream in AIDS patients: a phase I/II study

The efficacy and toxicity of foscarnet cream for the treatment of mucocutaneous herpes simplex virus lesions or lesions that were clinically unresponsive to systemic acyclovir treatment (median, 30.5 days) in AIDS patients were studied in a phase I/II, open-label, nonrandomized multicenter trial. In the study, 20 patients with advanced stages of AIDS were treated with foscarnet 1% cream five times a day for a mean duration of 34.5 days. Response of index lesions (n = 20) was judged to be completely healed (8 lesions), excellent (4 lesions), or good (1 lesion) in 65% of lesions. The median time to first negative herpes simplex virus culture of index lesion was 8 days. Among 15 patients with pain at baseline, 11 had complete resolution of pain and 2 had at least a 50% reduction. Clinical adverse events included skin ulceration (4 patients), application site reactions (3 patients), fever (3 patients), and headache (3 patients). Five (25%) patients developed new lesions due to herpes simplex virus at sites other than those being treated topically while enrolled in the study. Topical foscarnet 1% cream appears to be a safe and effective treatment for acyclovir-unresponsive mucocutaneous herpes simplex virus infection in AIDS patients.

Coresistance to zidovudine and foscarnet is associated with multiple mutations in the human immunodeficiency virus type 1 reverse transcriptase

Human immunodeficiency virus type 1 (HIV-1) isolates obtained from a patient with AIDS were assessed for coresistance to foscarnet and zidovudine. An HIV-1 strain (AP20) coresistant to foscarnet and zidovudine was isolated after 20 months of continuous combination therapy. The reverse transcriptase (RT) gene of AP20 had 41 substitutions which were different from the HXB2-D sequence and 9 that were different from the sequence of its foscarnet-sensitive, zidovudine-resistant progenitor virus (AP6). Six of these mutations were nonpolymorphic (T39A, V108I, K166R, K219R, K223Q, and L228R). Both strains had the conventional mutations mediating zidovudine resistance. In vivo selection may result in HIV-1 strains that are coresistant to foscarnet and zidovudine, but coresistance appears to require a complex evolutionary path and multiple RT mutations.

Current management of infectious complications in the injecting drug user

The diagnosis and management of infectious complications associated with injection drug use (IDU) are among some of the more challenging aspects of working with substance abusing populations. As the population of injection drug users age, we expect the number and severity of these complications to increase. Commonly seen infections, such as bacterial endocarditis and bacterial infections of bones, joints, and soft tissue, are now frequently complicated by concurrent immunodeficiency. Parenterally and sexually transmitted viral hepatitis is responsible for significant IDU morbidity and mortality. The human leukemia/lymphoma virus types I and II are increasing in prevalence in the IDU with uncertain long-term clinical effects. Immune dysfunction has been described in the IDU for decades, but the impact of host immune compromise on the transmission and the course of HIV-1 has yet to be fully appreciated. The integration of the treatment of substance abuse and its concurrent psychiatric disorders with the management of infectious complications, including immunodeficiency, promises to improve patient compliance with possible savings of overall medical costs.

What clinicians need to know about antiviral drugs and viral resistance

The development of safe and effective antiviral therapies for the management of a variety of viral infections has expanded tremendously in recent years. Treatment is now possible for serious and potentially life-threatening infections with herpesviruses, respiratory viruses such as influenza A and respiratory syncytial virus, and the human immunodeficiency virus. The increased availability and use of antiviral drugs, however, has led to the emergence of drug-resistant viruses, especially in immunocompromised hosts. With this review, the major antiviral agents are presented with a description of the mechanisms of action, the evolution of drug resistance, and the need for in vitro antiviral susceptibility testing.

Drug treatment of HIV-related opportunistic infections

The AIDS epidemic has led to the emergence of several disease entities which in the pre-AIDS era were rare or seemingly innocuous. Experience of treating these diseases varies. In some instances, such as Pneumocystis carinii pneumonia, there is an abundance of published literature to direct our course of action. However, for many of these newly recognised diseases our treatment experience is limited. Furthermore, in many instances, well controlled trials evaluating treatment modalities in the AIDS population are lacking. We have identified 13 disease entities (P. carinii pneumonia, toxoplasmosis, cryptococcosis, histoplasmosis, Mycobacterium tuberculosis, Mycobacterium avium complex, cytomegalovirus, coccidioidomycosis, isosporiasis, candidosis, Kaposi's sarcoma, herpes simplex virus, and varicella zoster virus) and have reviewed the current literature with regard to their treatment.

Zidovudine resistance is suppressed by mutations conferring resistance of human immunodeficiency virus type 1 to foscarnet

Both foscarnet (PFA) and zidovudine (AZT) select for drug-resistant variants of human immunodeficiency virus type 1 (HIV-1), but the interactions between the mutations causing such resistance are unknown. The introduction of the previously identified PFA resistance mutation W to G at codon 88 (W88G), E89K, L92I, or Q161L into an HIV-1 strain having the four known AZT resistance mutations completely reversed high-level AZT resistance. Two additional PFA resistance mutations, W88S and S156A, partially suppressed AZT resistance. Phenotypic reversion of AZT resistance by W88S, W88G, E89K, L921, and S156A was associated with a concomitant suppression of PFA resistance. The degree to which PFA resistance mutations reversed AZT resistance was directly correlated with each mutation's ability to confer high-level PFA resistance (> or = 5.0-fold) and AZT hypersusceptibility in a wild-type genetic background. Highly PFA-resistant HIV- 1 strains were hypersusceptible to AZT; conversely, AZT-resistant strains with M41L and T215Y; M41L, L210W, and T215Y; or M41L, D67N, K70R, and T215Y mutations were 2.2- to 2.5-fold hypersusceptible to PFA. Prolonged in vitro selection of wild-type or AZT-resistant HIV-1 strains with the combination AZT and PFA failed to generate coresistant virus, indicating that dual resistance was relatively difficult to achieve. Strains selected by passage in PFA plus AZT were phenotypically PFA resistant and AZT susceptible despite multiple reverse transcriptase mutations known to confer AZT resistance. These data show that PFA resistance mutations can phenotypically reverse AZT resistance and that AZT and PFA resistance might be mutually exclusive. The reciprocal interactions between AZT and PFA resistance-conferring mutations have implications for structure-function studies of the HIV-1 reverse transcriptase.

Herpesvirus resistance to antiviral drugs: a review of the mechanisms, clinical importance and therapeutic options

During the past decade, potent agents against herpes simplex virus (HSV) types 1 and 2, varicella zoster virus (VZV), and cytomegalovirus (CMV) have become available. The increasing clinical use of acyclovir, ganciclovir, and foscarnet has been associated with the emergence of drug-resistant herpesvirus strains. Resistance to acyclovir or ganciclovir most frequently results from deficient intracellular phosphorylation of these agents which is required for drug activation. Resistance to foscarnet is due to viral DNA polymerase mutants that permit viral replication despite the presence of the drug. In immunocompetent patients, herpesvirus resistance is rare and generally does not correlate with clinical outcome. In contrast, in immunocompromised hosts, resistance of HSV, VZV, and CMV is increasingly detected, and may be associated with disease refractory to antiviral therapy. Foscarnet treatment has been used with some clinical benefit in patients with acyclovir-resistant HSV or VZV, or ganciclovir-resistant CMV. For therapy of resistant mucocutaneous HSV disease, topical trifluorothymidine, and topical or intravenous cidofovir (HPMPC) have yielded encouraging results that warrant further investigation. Improved methods for detection of herpesvirus resistance, and validation of alternative therapy for patients with documented resistance are required to reduce the clinical impact of drug-resistant herpesviruses.

Pilot study of topical trifluridine for the treatment of acyclovir-resistant mucocutaneous herpes simplex disease in patients with AIDS (ACTG 172). AIDS Clinical Trials Group

SUMMARY

Twenty-six AIDS patients were enrolled in an open label pilot study to evaluate the efficacy and toxicity of topical 1 percent ophthalmic trifluridine solution for the treatment of chronic mucocutaneous herpes simplex virus disease unresponsive to at least 10 days of acyclovir therapy. Susceptibility testing to acyclovir, trifluridine, and foscarnet was determined by plaque reduction assay. Twenty-four patients were evaluable for efficacy and 25 for toxicity analyses. Seven patients (29 percent) had complete healing of lesions. The overall estimated median time to complete healing was 7.1 weeks. An additional seven patients had > or = 50 percent reduction in lesion area. The overall estimated median time to 50 percent healing was 2.4 weeks. Ten (42 percent) patients discontinued treatment for reasons other than primary treatment failure and seven (29 percent) for failure to respond to therapy. Baseline patient characteristics associated with greater reduction in lesion area included higher Karnofsky score (p = 0.05), fewer lesions (p = 0.07), smaller lesion area (p = 0.11), and trifluridine susceptibility (p = 0.07). Eight (33 percent) patients developed new lesions outside of the treatment area while on study, reflecting the local nature of this therapy. No dose-limiting toxicity attributable to trifluridine was reported. Given the limited options for the treatment of acyclovir-resistant herpes simplex disease, topical trifluridine may be a useful alternative in selected patients.

Foscarnet alters antidiuretic hormone-mediated transport

Therapy with foscarnet is associated with acute renal failure. Prior studies have emphasized foscarnet's proximal tubular toxicity, but there have been isolated reports of foscarnet-induced nephrogenic diabetes insipidus. As a phosphate analog, foscarnet is a competitive inhibitor of NaPO4 cotransport. However, foscarnet's effect on antidiuretic hormone (ADH)-induced transport has not been previously investigated. We studied foscarnet's modulation of transport in the toad urinary bladder. Foscarnet at 10 microM to 10 mM did not alter basal water or urea flux. Urea transport induced by a maximal dose of ADH (24 mIU/ml) was inhibited by 0.1 to 5.0 mM foscarnet. In tissues challenged with 0.5 to 1.0 mIU of ADH per ml, 1.0 to 10 mM foscarnet increased water flow but did not alter urea flux. Foscarnet also increased water flow induced by 1.0 to 10 microM forskolin. In tissues pretreated with 10 microM naproxen, foscarnet did not alter water flow induced by 0.5 to 1.0 mIU of ADH per ml or forskolin. These results indicate that foscarnet stimulates water flow induced by 0.5 to 1.0 mIU of ADH per ml at a site proximal to that of the generation of cyclic AMP and inhibits urea flux induced by a maximal dose of ADH at a separate site. In humans, foscarnet nephrotoxicity is likely not limited to the proximal nephron, but extends to the collecting duct. Patients receiving foscarnet should be closely monitored for disorders of urinary concentration.

Cutaneous manifestations of opportunistic infections in patients infected with human immunodeficiency virus

Bacillary angiomatosis (BA) presents most commonly as a cutaneous disease and is caused by two organisms. Bartonella (Rochalimaea) henselae and Bartonella (Rochalimaea) quintana. Biopsy confirmation of cutaneous BA is essential because lesions can mimic nodular Kaposi's sarcoma in appearance. Although the vast majority of human immunodeficiency virus (HIV)-infected patients with BA have CD4 lymphocyte counts of less than 100 cells per mm3, the disease responds well to antimicrobial therapy. Staphylococcus aureus is the most common bacterial skin pathogen affecting HIV-infected patients. The prevalence of skin disease due to S. aureus may be explained by high nasal carriage rates for the organism ( > or = 50%) and altered immune function in conjunction with an impaired cutaneous barrier. Herpes simplex virus causes mucocutaneous disease early in the course HIV infection and ulcerative lesions at any site in advanced HIV infection. Herpes zoster is common early in the course of HIV infection; recurrent and disseminated herpes zoster infections are characteristic of patients with advanced HIV disease. Acyclovir resistance is usually seen in patients with large, untreated, ulcerative lesions of herpes simplex virus and in patients with chronic, verrucous lesions of varicella-zoster virus. Cutaneous cryptococcosis, histoplasmosis, and coccidiomycosis are markers of disseminated disease and require biopsy confirmation. Scabies is easily diagnosed but may be atypical in presentation and difficult to eradicate in advanced HIV disease.

Resistance to antivirals

The ability of viruses to develop resistance to antiviral agents is already a major concern with respect to HIV. This article reviews mechanisms and clinical correlates of antiviral resistance and alternative drugs for treatment of infections due to resistant strains of HIV, herpes simplex virus, cytomegalovirus, varicellazoster virus, and influenza A.

Intravenous immunoglobulins suppress the recurrences of genital herpes simplex virus: a clinical and immunological study

Effective treatment is not currently available for suppressing the recurrence of genital herpes simplex virus (HSV) infections. Since intravenous immunoglobulins (IVIG) proved useful against HSV in experimental models, we treated patients with very high frequency of HSV genital recurrences (more than 15 episodes per year) with IVIG (400 mg/Kg every fourth week). The control group was treated with intermittent oral acyclovir (800 mg twice a day for one week every month). Both groups were treated for six months and, then, patients were followed-up to further six months. Both IVIG and acyclovir were effective in reducing the frequency of HSV genital recurrences as compared to base-line. However, patients treated with IVIG had a more striking reduction in the frequency of recurrences as well as both a shorter mean duration and a minor severity of the lesions as compared to acyclovir-treated patients. Furthermore, we found a trend indicating IVIG as more effective in reducing the viral load. Since in IVIG-recipients we found a strong increase of peripheral blood lymphocytes with natural killer (NK) surface phenotype, we suggest that the clinical effectiveness of IVIG treatment is probably mediated via the expansion of NK cell populations. Our study indicates that the treatment with IVIG is an effective and safe tool for suppressing the recurrences of genital HSV infections.

Neurologic sequelae associated with foscarnet therapy

OBJECTIVE

To report three cases of possible foscarnet-induced neurologic sequelae.

CASE SUMMARY

We report two cases of seizures and one case of hand cramping and finger paresthesia after starting foscarnet therapy with no evidence of predisposing risk factors, such as serum laboratory abnormalities, renal dysfunction, or known central nervous system (CNS) involvement. All three patients had stable laboratory values during therapy and when the neurologic adverse effects occurred. All patients were receiving appropriate dosages of foscarnet.

DISCUSSION

The incidence of seizures in AIDS patients was reviewed. A history of CNS lesions, infections, and/or AIDS per se may increase the risk of a neurologic adverse effect while receiving foscarnet therapy. Acute ionized hypocalcemia may cause these neurologic adverse effects. Ionized hypocalcemia is transitory, is related to the rate of foscarnet infusion, and may not be reflected as a change in total serum calcium concentration.

CONCLUSIONS

Foscarnet probably contributed to the neurologic adverse effects reported here. Foscarnet may need to be administered at a slower rate than is recommended by the manufacturer. Electrolytes must be monitored closely; however, a neurologic adverse effect may not be foreseen.

Foscarnet. A reappraisal of its antiviral activity, pharmacokinetic properties and therapeutic use in immunocompromised patients with viral infections

The DNA polymerase of human herpes viruses, including cytomegalovirus (CMV), and the reverse transcriptase of human immunodeficiency virus (HIV) are selectively inhibited in vitro by the pyrophosphate analogue foscarnet. Inhibition is reversible on withdrawal of foscarnet and additive or synergistic effects have been demonstrated in vitro with other antiviral drugs, including ganciclovir and zidovudine. Foscarnet appears to have negligible effects on host enzymes and cells. Complete or partial clinical resolution of ocular symptoms is obtained in more than 89% of patients with acquired immunodeficiency syndrome (AIDS) and CMV retinitis during foscarnet induction therapy, but relapse occurs soon after ceasing treatment. Maintenance treatment given daily can extend the period of remission considerably. Foscarnet and ganciclovir monotherapy had similar efficacy in the treatment of CMV retinitis in patients with AIDS in several studies, and have been used concomitantly in immunocompromised patients with recalcitrant CMV infections. In 1 trial, patients receiving foscarnet survived for significantly longer than those receiving ganciclovir. Foscarnet has been used successfully in the treatment of limited numbers of immunocompromised patients with CMV-associated gastrointestinal (improvement in over 67% of patients) and other infections. Aciclovir-resistant herpes simplex infections in immunocompromised patients have also been treated successfully with foscarnet. Almost 90% of a foscarnet dose is excreted in the urine. Reversible nephrotoxicity is common during foscarnet therapy, but may be reduced by dosage adjustment and adequate hydration. Anaemia, nausea and vomiting, disturbances in electrolyte levels and genital ulceration have also been associated with administration of the drug. The different tolerability profiles of foscarnet and zidovudine facilitate the use of these agents in combination in patients with AIDS and CMV infection; whereas ganciclovir, like zidovudine, is associated with dose-limiting haematological toxicity. The apparent survival benefits seen in these patients when receiving foscarnet and zidovudine (possibly linked to synergy between zidovudine and foscarnet and/or the inherent anti-HIV activity of foscarnet), appear to offer potentially important advantages for foscarnet over ganciclovir in the treatment of selected patients with AIDS and CMV infections.

A rapid and reliable assay for testing acyclovir sensitivity of clinical herpes simplex virus isolates independent of virus dose and reading time

The determination of acyclovir (ACV) sensitivity of clinical herpes simplex virus (HSV) isolates was studied by means of a cytopathic effect (CPE) inhibitory assay (CIA). Medium of HSV-infected Vero cells was supplemented with different ACV concentrations. The CPE was read quantitatively by light microscopy. The inhibitory dose for 50% CPE reduction (ID50) was calculated by applying 1st or 3rd degree regression lines, and aspects of different methods for calculation are discussed. The CIA proved highly reproducible. Surprisingly, the obtained ACV-ID50 values were independent of reading time and virus dose used in the test. In comparison to dye-uptake assay, CIA could be evaluated earlier. Therefore, CIA provides simple, rapid, and precise determination of ACV sensitivity of clinical HSV-isolates which can be achieved within 1 or 2 days after the virus has been isolated out of a clinical specimen.

Increased survival of a cohort of patients with acquired immunodeficiency syndrome and cytomegalovirus retinitis who received sodium phosphonoformate (foscarnet)

PURPOSE

To evaluate the impact of foscarnet on the longevity of persons with human immunodeficiency virus, type 1 (HIV-1) infection and cytomegalovirus (CMV) retinitis.

PATIENTS AND METHODS

A cohort of 24 patients with acquired immunodeficiency syndrome (AIDS) and CMV retinitis received sodium phosphonoformate (foscarnet) as part of a controlled efficacy trial at the National Institutes of Health. Foscarnet was continued for as long as it was tolerated. Antiretroviral therapy was given to the patients as tolerated. Long-term follow-up was available on all patients.

RESULTS

Seventeen patients received zidovudine during or after receiving foscarnet, 2 patients received dideoxyinosine, 2 patients zidovudine and dideoxyinosine, and 3 patients received no specific antiretroviral agent. Patients received foscarnet for a mean of 6.2 months (median, 4 months; range, 10 days to 22 months). Ten patients required a change to ganciclovir therapy at some time after receiving foscarnet. The median time from the diagnosis of CMV retinitis until death was 13.5 months (range, 3 to 34 months). Patients lived longer than untreated or ganciclovir-treated historical controls with AIDS and CMV retinitis. There was no difference in the survival of patients treated with foscarnet at the time of diagnosis and those patients treated with foscarnet only after progression of their CMV retinitis.

CONCLUSIONS

These data suggest that foscarnet may prolong the survival of persons with AIDS and CMV retinitis and should be the initial treatment of choice in these patients.

Impact of herpesvirus infections in the future

Numerous diverse, often opposing, trends will determine the frequency (and severity) of herpesvirus infections in the future. A major factor is the growing population of iatrogenically immunocompromised patients, accruing especially from large increases in organ and autologous bone marrow transplantation. Of even greater importance is the immense number of human immunodeficiency virus (HIV)-infected patients for whom herpesviruses may: (1) have been a cofactor in acquisition of HIV infection; (2) contribute to in vivo activation of HIV; (3) cause severe infections. Another factor influencing severe herpesvirus infections is the aging of populations in developed countries; this will be associated with a greater prevalence, and more morbid manifestations, of herpes zoster. Sociologic changes will also be important. The consequences of these, such as attempts to influence sexual practices, will be difficult to predict. Other changes, such as more frequent use of early child care facilities, will predictably lead to early acquisition of most herpesviruses, thereby decreasing the incidence of severe disease in adulthood. Factors that will reduce the incidence and/or severity of herpesvirus infections include vaccines (varicella, herpes simplex, cytomegalovirus); prophylactic strategies for immunocompromised hosts (passive immunization, antiviral drugs, blood product selection); more rapid and sensitive diagnostic methods; and suppressive or early antiviral therapy for common infections, such as genital herpes simplex and varicella.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of herpesvirus infections in HIV-infected individuals

OBJECTIVE

To discuss strategies available for the treatment of herpesvirus infections in individuals infected with HIV.

DATA SOURCES

Information was obtained from controlled and uncontrolled clinical trials, abstracts, conference proceedings, and review articles.

STUDY SELECTION

Emphasis was placed on controlled investigations in subjects infected with HIV.

DATA EXTRACTION

Data from human studies were extracted by the author and evaluated according to the patient population studied, sample size, dosage regimen, and therapeutic response.

DATA SYNTHESIS

Herpes group viruses are common opportunistic pathogens in HIV-infected individuals. Zoster, caused by varicella-zoster virus (VZV), is an early indication of the loss of cell-mediated immunity and HIV disease progression. Anorectal mucocutaneous disease is the most common manifestation caused by herpes simplex virus (HSV). Acyclovir is the drug of choice for treatment of both VZV and HSV infections. Cytomegalovirus (CMV) is the most common life-threatening viral infection in patients with AIDS; retinitis is the most frequent clinical manifestation. The response rate of CMV retinitis to initial treatment with either ganciclovir or foscarnet is equivalent, approximately 60-90 percent. Recent data suggest that the survival benefit may be greater with foscarnet.

CONCLUSIONS

Advances in the development and application of antiviral drugs for herpes group viruses have made treatment and, in some cases, prevention of infections possible. Future efforts, aimed at earlier intervention and suppression of latent virus, may offer additional improvement in quality of life for the HIV-infected individual.

Antiviral therapy: current concepts and practices

Drugs capable of inhibiting viruses in vitro were described in the 1950s, but real progress was not made until the 1970s, when agents capable of inhibiting virus-specific enzymes were first identified. The last decade has seen rapid progress in both our understanding of antiviral therapy and the number of antiviral agents on the market. Amantadine and ribavirin are available for treatment of viral respiratory infections. Vidarabine, acyclovir, ganciclovir, and foscarnet are used for systemic treatment of herpesvirus infections, while ophthalmic preparations of idoxuridine, trifluorothymidine, and vidarabine are available for herpes keratitis. For treatment of human immunodeficiency virus infections, zidovudine and didanosine are used. Immunomodulators, such as interferons and colony-stimulating factors, and immunoglobulins are being used increasingly for viral illnesses. While resistance to antiviral drugs has been seen, especially among AIDS patients, it has not become widespread and is being intensely studied. Increasingly, combinations of agents are being used: to achieve synergistic inhibition of viruses, to delay or prevent resistance, and to decrease dosages of toxic drugs. New approaches, such as liposomes carrying antiviral drugs and computer-aided drug design, are exciting and promising prospects for the future.