Acyclovir-resistant herpes simplex virus infections in patients with the acquired immunodeficiency syndrome

Pediatric human immunodeficiency virus infection

In the past decade, an increase in pediatric human immunodeficiency virus (HIV) infection has had a substantial impact on childhood morbidity and mortality worldwide. The vertical transmission of HIV from mother to infant accounts for the vast majority of these cases. Identification of HIV-infected pregnant women needs to be impoved so that appropriate therapy can be initiated for both mothers and infants. While recent data demonstrate a dramatic decrease in HIV transmission from a subset of women treated with zidovudine during pregnancy, further efforts at reducing transmission are desperately needed. This review focuses on vertically transmitted HIV infection in children, its epidemiology, diagnostic criteria, natural history, and clinical manifestations including infectious and noninfectious complications. An overview of the complex medical management of these children ensues, including the use of antiretroviral therapy. Opportunistic infection prophylaxis is reviewed, along with the important role of other supportive therapies.

Long-term oral acyclovir therapy. Effect on recurrent infectious herpes simplex keratitis in patients with and without grafts

PURPOSE

To evaluate the efficacy of long-term oral acyclovir therapy in reducing recurrences of dendritic or geographic herpes simplex keratitis (HSK).

METHODS

Thirteen patients with a history of frequently recurring HSK were followed before (mean, 27 months) and during long-term systemic acyclovir, and eight were followed after the acyclovir was discontinued.

RESULTS

Treatment ranged from 8.5 to 62 months (mean, 34 months). During treatment, the number of recurrences per month decreased from 0.15 to 0.03, and the average duration of relapses decreased from 12.6 to 7.8 days. Recurrences correlated with daily doses of oral acyclovir of 800 mg or less, intraocular surgery within 6 weeks of initiating treatment, and discontinuation of therapy against medical advice.

CONCLUSION

The results of this small study appear to demonstrate the efficacy of long-term oral acyclovir in prophylaxis of recurrent epithelial herpes simplex infection: therapeutic doses of oral acyclovir reduce both the rate and duration of recurrences of infectious herpetic keratitis. A multicenter, double-masked, placebo-controlled study is indicated.

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.

Clinical characteristics of acyclovir-resistant herpetic keratitis and experimental studies of isolates

BACKGROUND

We treated two patients with dendritic keratitis that did not respond to acyclovir (ACV) ointment therapy. Their systemic immune status was normal: however, one patient had a long history of atopic disease and the other had previously undergone topical corticosteroid treatment. HSV-1 was isolated from the patients and inoculated into animals to investigate its viral pathogenicity and latent infection.

METHODS

HSV-1 isolates from the patients were tested for drug sensitivity to acyclovir, ganciclovir, idoxuridine, trifluridine, foscarnet and interferon-beta in vitro. In in vivo studies, bilateral corneas of two New Zealand white rabbits and 10 BALB/c mice in each of four groups were infected by the respective viral isolates. The extent of corneal epithelial and/or stromal lesions produced by the viruses was evaluated. The trigeminal ganglial tissues of the mice were examined for viral latent infection by co-culture with Vero cells.

RESULTS

Herpetic keratitis in both patients was characterized by prolonged clinical course, succeeded by various types of corneal lesions and ocular complications. In in vitro studies, the two HSV-1 isolates demonstrated cross-resistance to ACV, ganciclovir and/or idoxuridine. Both strains demonstrated weakly virulent corneal epithelial and/or stromal lesions in rabbits and mice. One isolate displayed delayed advent but prolonged course of epithelial lesions in rabbits. The latent infection incidences of the isolates in mice trigeminal ganglia were 6.25% (1/16) and 0% (0/18) respectively.

CONCLUSION

Topical immune depression may induce ACV-resistant HSV-1 infection in the cornea, with a prolonged course in association with ocular complications. The prolonged infectious course of the viral isolates in the animal study partially supported the clinical demonstrations in the patient. The existence of latent infection by one ACV-resistant HSV-1 in its animals may indicate the possibility of its recurrence. Trifluridine may be an alternative choice for treating corneal epithelial lesions caused by ACV-resistant HSV-1.

Acyclovir prophylaxis of oral herpes virus during bone marrow transplantation

Oropharyngeal shedding of herpes viruses (herpes simplex, cytomegalovirus) was assessed in patients on standard acyclovir prophylaxis during bone marrow transplantation (BMT) to determine the frequency of viral shedding and to assess possible oropharyngeal complications that may be associated with viral reactivation in these patients. We conducted a prospective assessment of 83 patients receiving BMT. Patients were evaluated weekly and oral surveillance cultures were completed. Shedding of herpes simplex virus (HSV) was detected in the oropharynx of 2.9% of seropositive patients on prophylactic acyclovir, and only one case of clinical oral herpetic infection was seen. Cytomegalovirus (CMV) was cultured from the oropharynx in 13.3% of CMV seropositive patients provided with prophylactic acyclovir, but no oropharyngeal lesions were attributed to CMV reactivation. No correlation was seen between HSV and CMV pretransplant serology and severity of oral mucositis and acute graft versus host disease. No effect on time to engraftment was detected. This study supports the continuing use of acyclovir prophylaxis in HSV seropositive patients receiving BMT. Acyclovir prophylaxis was effective in preventing viral shedding in all but 2.9% of patients, and only one case of clinical infection was diagnosed. The frequency of CMV shedding was approximately four times that of HSV; however, no oral lesions were attributed to CMV.

Clinical evaluation of carbocyclic oxetanocin G eyedrops in the treatment of herpes simplex corneal ulcers

BACKGROUND

Acyclovir (ACV) ophthalmic ointment is effective in the treatment of herpetic keratitis. However, when applied, the ointment has an unpleasant feeling and some cases are resistant to ACV. A new antiviral compound, carbocyclic oxetanocin G (C.OXT-G) has potent anti-herpes simplex virus activity and high water solubility, so the clinical effect of C.OXT-G eyedrops on ulcerative herpetic keratitis was evaluated.

METHODS

Studies were conducted on the corneal ulcers in 37 eyes of 27 patients. Patients with typical dendritic or geographic corneal ulcers were treated with 0.1% C.OXT-G eyedrops, applied five times a day, together with eyedrops of an antibiotic applied four times a day. The eyes were examined at least twice a week until the ulcers healed, and thereafter at intervals for up to 3 months.

RESULTS

All of the ulcers healed, their average healing time being 4.9 (SD 2.2) (range 2 to 9) days. The ulcers in 20 of the 37 eyes were induced by the use of corticosteroid or immunosuppressive drugs, and their average healing time was 4.8 (2.3) days. No adverse drug reactions were seen during the observation period in this trial.

CONCLUSION

Eyedrops containing 0.1% C.OXT-G are excellent and safe for treatment of herpes simplex corneal ulcers in humans.

Topical treatment of cutaneous herpes simplex virus-1 infection in mice with a specially formulated caffeine gel (Cafon)

Caffeine, although not a nucleoside analog, is known to inhibit the replication of herpes simplex virus-1 (HSV-1) and has been shown to significantly limit the spread of HSV infection in vitro. The therapeutic efficacy of caffeine was examined in a murine cutaneous infection model. The midflanks of 6-week-old BALB/c mice were infected with HSV cutaneously after application of 10% caffeine (Cafon) gel, and was reapplied to the midflank 5 times daily thereafter. Treatment with Cafon gel significantly retarded the development of skin lesions. Both midflanks were cutaneously infected, and a placebo and active gel were applied to the right and left midflanks respectively. Cafon gel significantly retarded the appearance of vesiculation and reduced the number of vesicles compared with the placebo gel. Cafon gel was as effective as 5% acyclovir ointment, and no significant difference was observed in the development of local lesions between these two topical preparations. The efficacy of Cafon gel also corresponded to that of oral treatment with 5 mg/kg or more of acyclovir in our cutaneous infection system. These results suggest that Cafon gel can be useful for the topical treatment of cutaneous HSV infection.

Comparison of a DNA probe assay with the plaque reduction assay for measuring the sensitivity of herpes simplex virus and varicella-zoster virus to penciclovir and acyclovir

A DNA probe assay was compared with the plaque reduction assay to determine the sensitivity of clinical isolates of herpes simplex virus (HSV) and varicella-zoster virus (VZV) to penciclovir and acyclovir in MRC-5 cells. In both assays, penciclovir and acyclovir shared comparable activity against cell-free virus (CFV) preparations of VZV and herpes simplex virus type 1 (HSV-1) isolates, whilst acyclovir was significantly more active than penciclovir against herpes simplex virus type 2 (HSV-2) isolates in both the DNA probe assay (P < or = 0.01) and the plaque reduction assay (P < or = 0.01). However, the 50% effective concentrations (EC50s) were generally lower in the DNA probe assay and the correlation between the plaque reduction and DNA probe assays was poor for either compound. Six acyclovir-resistant strains of HSV-1 derived in cell culture were also tested for susceptibility to penciclovir and acyclovir, in the DNA probe and plaque reduction assays. The relative susceptibilities of these strains were comparable, for example, one ACV-resistant strain was susceptible to penciclovir in both assays. Further comparisons of the assay methods were made using cell-associated VZV (CAV). As with CFV the EC50s were significantly lower in the DNA probe assay than the plaque reduction assay for penciclovir (P < or = 0.01) and acyclovir (P < or = 0.01). In the DNA probe assay there was no significant difference in the EC50s for either penciclovir or acyclovir when comparing CAV with CFV. However, in the plaque reduction assay the EC50s for CAV were significantly higher than those for CFV for both penciclovir (P < or = 0.01) and acyclovir (P < or = 0.01). Overall the DNA probe assay is objective, does not require prior titration of isolates and provides opportunities for automation. It is more suitable for sensitivity testing of large numbers of clinical isolates than the well-established plaque reduction assay.

Management of genital herpes

Oral acyclovir is the therapy of choice for treatment of first-episode genital herpes, for suppression of frequently recurrent genital herpes, and, in selected patients, for episodic treatment of recurrent genital herpes. Topical acyclovir therapy is relatively or totally ineffective and is therefore discouraged. Indications for intravenous acyclovir therapy of mucocutaneous HSV infections include patients hospitalized with severe first-episode genital herpes and immunocompromised patients who have severe infections or who cannot swallow the oral preparation. The most promising investigational drugs are the oral prodrugs valaciclovir and famciclovir. Famciclovir is licensed in the U.S. for treatment of zoster but not for treatment of mucocutaneous genital herpes. When used for episodic therapy of recurrent genital herpes, both famciclovir and valaciclovir effectively reduce the duration of viral shedding, lesion healing times, and the duration of symptoms. Suppressive therapy with famciclovir has also been shown to be effective in reducing the frequency of episodes in women with frequently recurring genital herpes. Although these drugs can be given less frequently than oral acyclovir, there is yet no clear indication that they are more effective or better tolerated than oral acyclovir.

Genital tract infections in women

The future holds promise of new, more accurate diagnostic tests; more effective therapies; and development of better barriers and eventual vaccines. GTI is, however, and for the foreseeable future will continue to be a major health care problem for women, requiring careful surveillance, management, and ongoing education for both patient and provider.

Antiviral agents in dermatology: current status and future prospects

The majority of current antiviral agents have become available only during the past decade. The above mentioned antiviral drugs, especially the viral-TK-specific agents have attempted to bring antiviral therapy on par with antimicrobial therapy. The fact, that cells infected with viruses can be selected against the relatively low toxicity to the patient, highlights the present state of antiviral therapy. Since viral infection can be viewed as an integral component of the self (i.e., a condition that cannot simply be surgically eliminated), the science of medicine is turning to the components of the self to overcome such conditions. By administering immune-system-derived agents (e.g., interferons) or compounds that stimulate the immune system (e.g., adjuvants like imiquimod), previously unmanageable conditions become manageable. The future of antiviral therapy will undoubtedly be at the molecular level. With greater understanding of the virus and the immune system with which it interacts, more specific and efficacious antiviral agents will be added to the arsenal of the clinician.

Biochemical basis for increased susceptibility to Cidofovir of herpes simplex viruses with altered or deficient thymidine kinase activity

It has been observed that herpes simplex virus mutants with deficient or altered thymidine kinase activity are more susceptible to Cidofovir (CDV; 1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine dihydrate) in tissue culture than are the parental strains. During infection of cells, the elevation of the dCTP pool by thymidine kinase mutant viruses is less than that induced by the wild-type virus. The competition between CDV diphosphate and dCTP at the viral polymerase is therefore changed in favor of CDV diphosphate, enhancing its activity.

A comparative evaluation of three methods of antiviral susceptibility testing of clinical herpes simplex virus isolates

BACKGROUND

Current methods of antiviral susceptibility testing for herpes simplex virus (HSV) are poorly standardized and have rarely been compared critically.

OBJECTIVES

To compare the three most commonly utilized HSV susceptibility assays for accuracy of result, method of implementation, and time required.

STUDY DESIGN

We compared susceptibility results for acyclovir and foscarnet using the plaque reduction, dye uptake and DNA hybridization assays in 30 patient isolates of HSV, of varying susceptibility pattern. Compared parameters included: values for ID(50) (the concentration of drug required to inhibit virus growth by 50% or more), ratio of ID(90) to ID(50), and correlation of susceptibility result with clinical response to antiviral therapy, when available. In addition, we compared ease of the assay, presence of objective endpoint, time required to generate the susceptibility result, and necessary equipment for implementation.

RESULTS

The dye uptake yielded ID(50) results that were approximately two-fold greater than those from the plaque reduction assay, while ID(50) values from the DNA hybridization assay were one-half those from the plaque reduction assay. Comparison of the correlation of susceptibility result with clinical response to acyclovir therapy in 17 instances and to foscarnet therapy in 10 instances suggested the possibility of a somewhat greater discriminative ability of the dye uptake assay, and a somewhat lesser discriminative ability of the DNA hybridization assay, when compared with results from the plaque reduction assay in isolates with borderline acyclovir susceptibility.

CONCLUSIONS

Larger comparative studies are necessary to further differences in discriminative ability of the three assays for HSV. All three assays were deemed suboptimal due to an overly long turnaround time, associated expense, and/or level of equipment required for their performance. Continued evaluation of alternative, more rapid assays is therefore warranted.

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.

Susceptibilities of several drug-resistant herpes simplex virus type 1 strains to alternative antiviral compounds

Resistant herpes simplex virus type 1 strains were obtained under the selective pressure of acyclovir, ganciclovir, bromovinyldeoxyuridine, foscarnet, 2-phosphonylmethoxyehtyl (PME) derivatives of adenine and 2,6-diaminopurine, 3-hydroxy-2-phosphonylmethoxypropyl derivatives of adenine and cytosine, and 2-amino-7-(1,3-dihydroxy-2-propoxymethyl)purine (S2242). The drug susceptibility profiles of resistant strains point to differences in the modes of action of PME and 3-hydroxy-2-phosphonylmethoxypropyl derivatives and common mechanisms of action of foscarnet, S2242, and PME derivatives against herpes simplex virus type 1 replication.

Infection prevention strategies for children with cancer and AIDS: contrasting dilemmas

Infectious complications represent significant challenges for children with cancer and those infected with HIV. Although both have similarities in the disease- and treatment-related alterations in host defences, there are significant differences that can have an impact on the approach to treatment and prevention of the dominant infectious complications. An important difference is that children with cancer readily recover from neutropenia. Thus, the immune deficits are interspersed with intervals of immunological recovery. On the other hand, children with HIV infection do not appreciably recover from the progressive, immunological changes associated with the underlying HIV infection. The loss of cellular and humoral immunity is generally not reversible, and thus the risk of infection only increases over time. Bacteria constitute the predominant pathogen for paediatric cancer patients but invasive mycoses, viruses and parasitic infections are emerging as important pathogens. In paediatric cancer patients, strategies have been directed at altering or suppressing the endogenous colonization patterns of pathogenic bacteria. The success of this approach has been limited and at the expense of selecting for antibiotic-resistant bacterial infections. Children with HIV infection are at risk of developing a wide spectrum of pathogens. Strategies for infection prevention in the HIV setting have been directed at specific organisms, generally using more specific antimicrobial agents and with greater success.

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.

Antiviral susceptibility testing with a cell line which expresses beta-galactosidase after infection with herpes simplex virus

Despite increasing concern about drug-resistant herpes simplex virus (HSV), antiviral susceptibility testing is not routinely performed by most clinical virology laboratories. This omission is in large part because the most widely accepted method, the plaque reduction assay (PRA), is cumbersome to perform and results are rarely available in time to influence treatment. We report here the development of a sensitivity test for HSV which utilizes a cell line (VeroICP6LacZ#7) that expresses beta-galactosidase activity after infection with HSV such that infected cells can be detected by histochemical staining. We designed an assay in which 10-fold dilutions of virus stocks with undetermined titers were inoculated onto VeroICP6LacZ#7 cells in a 24-well tissue culture dish. Forty-eight hours after infection, the cell monolayers were histochemically stained. Plaques appear blue against a clear background and are thus easily visualized at 48 h. As with the standard PRA, the 50% inhibitory concentration (IC50) was reported as the concentration of an antiviral drug that reduces the number of plaques by 50%. Evaluation of 10 well-characterized laboratory strains and 12 clinical HSV isolates showed that the IC50 determined by this method correlated in all instances with the IC50 determined by the PRA. This method is easy to use and eliminates the need to determine the titer of the virus, and results are available within 48 h of the detection of the virus. VeroICP6Lac#7 cells are a useful tool for performing HSV antiviral susceptibility testing and could be used in a number of different formats to facilitate the identification of drug-resistant isolates of HSV.

Efficacy of traditional herbal medicines in combination with acyclovir against herpes simplex virus type 1 infection in vitro and in vivo

Traditional herbal medicines have been safely used for the treatment of various human diseases since ancient China. We selected 10 herbal extracts with therapeutic antiherpes simplex virus type 1 (HSV-1) activity. Among these, Geum japonicum Thunb., Rhus javanica L., Syzygium aromaticum (L.) Merr. et Perry, or Terminalia chebula Retzus showed a stronger anti-HSV-1 activity in combination with acyclovir than the other herbal extracts in vitro. When acyclovir and/or a herbal extract were orally administered at doses corresponding to human use, each of the 4 combinations significantly limited the development of skin lesions and/or prolonged the mean survival times of infected mice compared with both acyclovir and the herbal extract alone (P < 0.01 or 0.05). These combinations were not toxic to mice. They reduced virus yields in the brain and skin more strongly than acyclovir alone and exhibited stronger anti-HSV-1 activity in the brain than in the skin, in contrast to acyclovir treatment by itself. Combinations of acyclovir with historically used herbal medicines showed strong combined therapeutic anti-HSV-1 activity in mice, especially reduction of virus yield in the brain.

Suppression of infectious virus spread to the liver by foscarnet following lethal infection of acyclovir-resistant herpes simplex virus type 2 in mice

Patients with the acquired immune deficiency syndrome (AIDS) occasionally develop hepatitis, pneumonia or esophagitis due to herpes simplex virus type 2 (HSV-2) infection. HSV hepatitis is a rare but serious complication in liver transplantation. Acyclovir-resistant HSV strains may emerge in immunocompromised patients. Following intraperitoneal inoculation, HSV-2 induces necrotizing hepatitis in mice. We studied the virus spread and mortality following intraperitoneal inoculation of HSV-2 RK (an acyclovir-resistant recombinant virus with altered thymidine kinase activity) as compared to its parent virus 8620K. Neither the 50% lethal dose (LD50) nor the average survival time was significantly different between the two strains. Parenteral acyclovir treatment was found to be effective against 8620K but not RK infection. Parenteral foscarnet treatment was effective against both RK and 8620K, and also inhibited the spread of either virus to the liver, spinal cord and brain. Peroral foscarnet administration was found to prevent the virus growth in the liver.

Comparison of genetically engineered herpes simplex viruses for the treatment of brain tumors in a scid mouse model of human malignant glioma

Genetically engineered viruses and viral genes inserted into retroviral vectors are increasingly being considered for experimental therapy of brain tumors. A primary target of these viruses and vectors is human gliomas, the most frequently occurring primary human brain tumor. To investigate the potential of genetically engineered herpes simplex viruses (HSVs) in the therapy of these tumors, we compared the attributes of two viruses, a recombinant from which the gamma 1(34.5) gene had been deleted (R3616) and a recombinant in which the gamma 1(34.5) gene had been interrupted by a stop codon (R4009). Previous studies have shown that these recombinants were completely devoid of the ability to multiply in the central nervous system of rodents. To pursue these studies, we developed a scid mouse glioma model. Tumor cell response (survival) for 10(3), 10(4), and 10(5) implanted MT539MG glioma cells was 38, 23, and 15 days, respectively. The results were as follows: (i) both R3616 and R4009 replicate and cause cytolysis in diverse glioma cell lines of murine and human origin in vitro, and (ii) Winn-type assays 10(5) MT539MG cells coinoculated with R3616 or R4009 as compared to saline significantly prolonged survival in a dose-dependent fashion. Mice that received only tumor cells or the wild-type parent strain of the recombinants, HSV-1(F), died within 15 days. Survival was greatest with R4009. These experiments define both a model for screening oncolytic viruses and a genetically engineered virus of significant potential use as an oncolytic agent.

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.

Sexually transmitted diseases and anal manifestations of AIDS

During the past 20 years, there has been an increased use of the anorectum for erotic pleasure. Consequently, this has led to an overwhelming rise in sexually transmitted diseases (STDs) of the anus and rectum. It is important that surgeons involved with the care of colon and rectal disorders be familiar with each of these diseases. The recent AIDS epidemic has been a challenge to the medical community. Equally as challenging is the management of common anorectal disorders in the AIDS patient. AIDS not only influences the manner in which STDs present but is associated with its own spectrum of anorectal disorders. Discussion and management of STDs and anorectal disorders of AIDS patients are presented.

Acyclovir-resistant, pathogenic herpesviruses

In herpes simplex virus, the simplest path to resistance to the drug acyclovir is a mutation that knocks out the enzyme thymidine kinase. Such mutants are highly attenuated in mouse models of viral pathogenesis, but have been reported to be associated with severe disease in immunocompromised patients. This review discusses possible resolution of this paradox.

Gastrointestinal disease in the immunocompromised patient

Gastrointestinal (GI) disease is frequent in all types of immunocompromised patients but occurs with greatest frequency in patients with acquired immunodeficiency syndrome (AIDS). Thus, much of this review deals with human immunodeficiency virus (HIV)-related GI diseases. Gastrointestinal diseases in other immunocompromised patients are compared with those in patients with AIDS. Conditions unique to transplant recipients, such as graft-versus-host disease (GVHD) and posttransplant lymphoproliferative disorders (PTLDs), are discussed separately. We have divided these GI diseases into four main categories: (1) HIV-related inflammatory conditions other than opportunistic infections (HIV-related enteropathy, proctocolitis, and CD8 lymphocytosis); (2) inflammatory conditions unrelated to HIV or opportunistic infections (neutropenic enterocolitis, regional enteritislike enteropathy, and GVHD); (3) opportunistic infections (illnesses caused by herpesvirus, cytomegalovirus, and miscellaneous other viruses; Mycobacterium, Candida, Histoplasma, Cryptococcus, Cryptosporidium, Microsporida, Isospora, Leishmania, Toxoplasma and Strongyloides organisms as well as Pneumocystitis carinii; and (4) neoplasias (Kaposi's sarcoma [KS], AIDS-related non-Hodgkin's lymphoma [NHL], HIV-related Hodgkin's disease [HD], PTLDs, and miscellaneous neoplasms). The prevalence, pathogenesis, clinical manifestations, gross pathological findings, and microscopic features of each disease entity are discussed.

Drug resistance in viruses

The mechanisms of action of antiviral drugs and of drug resistance are known in remarkable detail, partly because X-ray crystallographic structures are known for many target viral proteins. Resistance usually involves amino acid substitutions in the target protein that prevent drug binding or prevent an enzyme from accepting the drug as a substrate. This information allows more effective use of available drugs and aids the development of new drugs.

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.

Mutations in accessory DNA replicating functions alter the relative mutation frequency of herpes simplex virus type 1 strains in cultured murine cells

The contribution of the herpes simplex virus type 1 (HSV-1)-encoded uracil DNA glycosylase (UNG), thymidine kinase (TK), and dUTPase to the relative mutant frequency (RMF) of the virus in cultured murine cells was examined. A panel of HSV-1 mutants that lacked singly or doubly the UNG, TK, or dUTPase activity were generated by disruption of the enzyme coding regions with the Escherichia coli beta-galactosidase (beta-gal) gene in strain 17syn+. To establish a baseline RMF of strain 17syn+, the beta-gal gene was inserted into the UL3 locus. In all of the viruses, the beta-gal insert served as a phenotypic marker of RMF. A mutant plaque was identified by the lack of beta-gal activity and, in selected cases, positive in situ hybridization for beta-gal sequences. Replication kinetics in NIH 3T3 cells demonstrated that all of the mutants replicated efficiently, generating stocks with equivalent titers. Two independently generated UL3-beta-gal viruses were examined and established a baseline RMF of approximately 0.5% in both NIH 3T3 and LM TK- cells. Loss of dUTPase activity resulted in viruses with fivefold-increased RMFs, indicating that the HSV-1 dUTPase has an antimutator function. The RMF observed for the tk- viruses was reduced as much as 40-fold (RMF of 0.02%), suggesting that the viral TK is a mutator activity. The RMF of two independent UNG- viruses showed no significant difference from the baseline RMF in limited passage; however, following successive passage, the data suggested that UNG activity serves as an antimutator. These results have implications for the natural history of HSV and the development of antiviral therapies.

Implementation and evaluation of a standardized herpes simplex virus prophylaxis protocol on a leukemia/bone marrow transplant unit

OBJECTIVE

To assess the impact of a standardized acyclovir prophylaxis protocol for the prevention of herpes simplex virus (HSV) infection and disease in bone marrow transplant and leukemic patients.

DESIGN

Two-phase, open sequential study involving prospective patient monitoring and retrospective health record review.

SETTING

Tertiary care teaching hospital.

PATIENTS

Fifty-seven patients (35 preprotocol, 22 postprotocol) who received acyclovir for HSV prophylaxis during an 18-month study period.

INTERVENTIONS

An acyclovir HSV prophylaxis protocol was developed and implemented. Under this protocol, all HSV immunoglobulin G-seropositive hematology patients received an acyclovir regimen of 125 mg/m2 i.v. q6h or 600 mg p.o. q6h (if tolerated) from day -5 to day 30. Regimens not matching protocol were modified by pharmacists in conjunction with the prescriber. All treatment courses were followed daily by pharmacists to modify dosage according to renal function and assess appropriateness of the i.v. route. Tablets, capsules, or suspensions were promoted if the patient was considered tolerant of the oral route.

MAIN OUTCOME PARAMETERS

Outcome parameters included (1) incidence of parenteral, oral, or combined therapy; (2) total prophylactic acyclovir dose per patient; (3) mean prophylactic acyclovir daily dose; (4) mean duration of acyclovir prophylaxis; and (5) HSV reactivation rate.

RESULTS

Following implementation of the protocol, the mean total i.v. acyclovir dose per patient decreased from 20.1 g (range 3.6-109.5) to 11.7 g (range 1.0-43.0; p = 0.1162). The mean cumulative oral dose increased from 12.1 g (range 0.4-70.0) to 33.1 g (range 2.4-93.6; p = 0.0007). Mean duration of therapy increased from 27.6 to 33.5 days (p = 0.23). The mean duration of oral therapy increased from 10.5 days (+/- SD 10.9) to 17.2 days (+/- SD 12.1) (p = 0.034). The appropriateness of use of the i.v. dosage form increased from 53 to 88 percent of treatment days (p = 0.013). No difference in HSV reactivation rate was observed when comparing patients prior to and following protocol implementation. A drug acquisition savings of $1112.00 (CDN) per patient was realized.

CONCLUSIONS

The implementation of a standardized HSV acyclovir prophylaxis protocol has resulted in significant drug acquisition cost savings without an apparent negative impact on patient outcome.

Phase I trial of valaciclovir, the L-valyl ester of acyclovir, in patients with advanced human immunodeficiency virus disease

Valaciclovir, the L-valyl ester of acyclovir, is rapidly and extensively converted in humans to acyclovir after oral administration by first-pass metabolism. A phase I study was conducted in two cohorts of volunteers with advanced human immunodeficiency virus (HIV) disease (absolute CD4 lymphocyte count of < 150 cells per microliters) who received oral valaciclovir at dosages of 1,000 or 2,000 mg four times daily for 30 days. All patients were clinically stable without any changes in underlying HIV-related medications for > or = 6 weeks prior to entry in study; these medications were continued throughout the study. Multiple-dose administration of valaciclovir showed a generally favorable safety profile. Nausea, vomiting, diarrhea, and abdominal pain each were reported in < or = 31% of the patients; of these symptoms, only one episode of diarrhea was considered causally related to valaciclovir exposure. Four patients developed neutropenia (two at each dose level) which was not clinically significant. There were no renal or neurologic adverse events. Valaciclovir was rapidly absorbed and converted to acyclovir, with plasma valaciclovir levels generally undetectable or levels of < or = 0.4 microgram/ml. After 3 h postdosing, valaciclovir was not detectable in plasma. Acyclovir was measurable in plasma as early as 15 min following valaciclovir dosing, and plasma concentrations of acyclovir greatly exceeded those of valaciclovir. The mean values for the maximum concentration of drug in plasma, time to maximum concentration of drug in plasma, area under the concentration-time curve from 0 h to infinity, and apparent half-life of acyclovir obtained after single- and multiple-dose valaciclovir administration in HIV-infected patients were similar to those reported in normal healthy volunteers. The time to maximum concentration in serum and half-life of acyclovir after valaciclovir administration were approximately 2 and 3 h, respectively, which were similar to those reported after oral administration of acyclovir itself. The mean trough and peak acyclovir concentrations and the daily area under the concentration-time curve acyclovir values at steady state were 2.5 and 8.4 micrograms/ml and 120 h micrograms/ml, respectively, after a dosage of 2,000 mg of valaciclovir four times daily. These values were approximately fivefold greater than those achieved with high dosages of oral acyclovir (800 mg, five times daily) and were not affected by continued use of medications necessary for management of advanced HIV disease. Thus, 2,000 mg of valaciclovir given orally four times daily should be evaluated for its potential efficacy in suppressing cytomegalovirus and other herpes group virus infections not optimally managed with current oral acyclovir therapy.

A net +1 frameshift permits synthesis of thymidine kinase from a drug-resistant herpes simplex virus mutant

Clinical resistance to antiviral drugs requires that a virus evade drug therapy yet retain pathogenicity. Thymidine kinase (TK)-negative mutants of herpes simplex virus are resistant to the drug, acyclovir, but are attenuated for pathogenicity in animal models. However, numerous cases of clinical resistance to acyclovir have been associated with viruses that were reported to express no TK activity. We studied an acyclovir-resistant clinical mutant that contains a single-base insertion in its tk gene, predicting the synthesis of a truncated TK polypeptide with no TK activity. Nevertheless, the mutant retained some TK activity and the ability to reactivate from latent infections of mouse trigeminal ganglia. The mutant expressed both the predicted truncated polypeptide and a low level of a polypeptide that comigrated with full-length TK on polyacrylamide gels and reacted with anti-TK antiserum, providing evidence for a frameshifting mechanism. In vitro transcription and translation of mutant tk genes, including constructs in which reporter epitopes could be expressed only if frameshifting occurred, also gave rise to truncated and full-length polypeptides. Reverse transcriptase-polymerase chain reaction analysis coupled with open reading frame cloning failed to detect alterations in tk transcripts that could account for the synthesis of full-length polypeptide. Thus, synthesis of full-length TK was due to an unusual net +1 frameshift during translation, a phenomenon hitherto confined in eukaryotic cells to certain RNA viruses and retrotransposons. Utilization of cellular frameshifting mechanisms may permit an otherwise TK-negative virus to exhibit clinical acyclovir resistance.

Correlation between response to acyclovir and foscarnet therapy and in vitro susceptibility result for isolates of herpes simplex virus from human immunodeficiency virus-infected patients

In vitro susceptibility testing of herpes simplex virus (HSV) isolates will play an increasingly important role in guiding the clinical management of immunocompromised hosts who have lesions that are poorly responsive to therapy with standard antiviral agents. We assessed the correlation between the in vitro susceptibility result using a plaque reduction assay in Vero cells and the response to antiviral therapy with acyclovir or foscarnet for 243 clinical isolates of HSV collected from 115 human immunodeficiency virus-infected patients. The in vitro results and clinical responses were highly associated for both acyclovir and foscarnet (P < 0.001 and P < 0.001, respectively). The predictive values of a susceptible result (50% effective concentrations, < 2 micrograms/ml for acyclovir and < 100 micrograms/ml for foscarnet) for complete healing of lesions were 62% for acyclovir and 82% for foscarnet; the predictive values of a resistant result for failure to heal were 95% for acyclovir and 88% for foscarnet. Thus, in vitro testing has clinical utility in guiding therapy, although the 1 to 2 weeks required to derive a definitive result by the plaque reduction assay is a major limitation.

Periodontal diseases in HIV-infected patients

Periodontal diseases may be the first clinical sign of human immunodeficiency virus (HIV)-infection. Since the immunosuppression and subsequent susceptibility may alter the responses of the oral tissues as well as the microflora, both periodontal treatment and result of therapy may be modified. The periodontal diseases in HIV-seropositive patients include common as well as less conventional forms of gingivitis and periodontitis, and bacterial, mycotic and viral infections are seen. Neoplasias may also involve the periodontium; most common are Kaposi's sarcoma and non-Hodgkin's lymphoma. Recent studies of unselected groups of patients indicate that periodontal health in at least some groups of HIV-seropositive patients is better than previously reported.

Detection of herpes simplex virus (HSV) in the saliva from 1,000 oral surgery outpatients by the polymerase chain reaction (PCR) and virus isolation

Herpes simplex virus (HSV) was detected by a polymerase chain reaction (PCR) in 47 (4.7%) out of 1,000 saliva samples from the outpatients of an oral and maxillofacial surgery department compared with 27 (2.7%) by conventional virus isolation. There were 20 PCR-positive, culture-negative cases but no culture-positive, PCR-negative cases. Patients younger than 10 years or older than 60 years secreted HSV more frequently than the others. Those with inflammatory diseases showed higher positivity for HSV than those with malignancy, trauma or other complaints. All 27 virus isolates were typed as HSV type 1 and none were resistant to acyclovir, arabinofuranosyl-adenine, iododeoxyuridine or phosphonoacetic acid.