Acylovir in oral and ganglionic herpes simplex virus infections

Curcumin as an Antiviral Agent

Curcumin, the primary curcuminoid compound found in turmeric spice, has shown broad activity as an antimicrobial agent, limiting the replication of many different fungi, bacteria and viruses. In this review, we summarize recent studies supporting the development of curcumin and its derivatives as broad-spectrum antiviral agents.

The Interesting Case of Acyclovir Delivered Using Chitosan in Humans: Is it a Drug Issue or Formulation Issue?

PURPOSE

Attempts to formulate acyclovir to improve its bioavailability and reduce the frequency of dosing from the present q4h have not materialized.

DISCUSSION

It was thought that an approach using permeability enhancer such as chitosan may impart improved absorption profile to acyclovir; however, the recently published pharmacokinetic data suggested otherwise. The lack of promise of chitosan formulation was attributed to the muco-adhesive properties of chitosan to hold off acyclovir and preventing its transport across the gastrointestinal tract. However, the above hypothesis was refuted by another published human pharmacokinetic study of fexofenadine formulated with chitosan formulation - in this work it was unambiguously shown that chitosan helped in enhanced absorption of fexofenadine which is a well-known Pgp substrate. If one examines the pharmacokinetic disposition of acyclovir, it is clear that renal elimination is so rapid necessitating frequent dosing of acyclovir. In summary, the ability of chitosan based formulations to aid in the oral absorption of drugs may be drug dependent as enumerated by data obtained from acyclovir and fexofenadine. While chitosan favourably improved the pharmacokinetics of fexofenadine, acyclovir may not be ideal for chitosan type of formulation.

CONCLUSION

The choice of the drug and the formulation type intended to deliver the drug need to be made in a diligent and pragmatic fashion.

HSV-1 and Alzheimer's disease: more than a hypothesis

Among the multiple factors concurring to Alzheimer’s disease (AD) pathogenesis, greater attention should be devoted to the role played by infectious agents. Growing epidemiological and experimental evidence suggests that recurrent herpes simplex virus type-1 (HSV-1) infection is a risk factor for AD although the underlying molecular and functional mechanisms have not been fully elucidated yet. Here, we review literature suggesting the involvement of HSV-1 infection in AD also briefly mentioning possible pharmacological implications of these findings.

Oligomeric nucleic acids as antivirals

Based on the natural functions and chemical characteristics of nucleic acids, a variety of novel synthetic drugs and tools to explore biological systems have become available in recent years. To date, a great number of antisense oligonucleotides, RNA interference-based tools, CpG-containing oligonucleotides, catalytic oligonucleotides, decoys and aptamers has been produced synthetically and applied successfully for understanding and manipulating biological processes and in clinical trials to treat a variety of diseases. Their versatility and potency make them equally suited candidates for fighting viral infections. Here, we describe the different types of nucleic acid-based antivirals, their mechanism of action, their advantages and limitations, and their future prospects.

Valacyclovir treatment ameliorates the persistently increased pentylenetetrazol-induced seizure susceptibility in mice with herpes simplex virus type 1 infection

Herpes simplex virus type 1 (HSV-1) is an important pathogen related to epilepsy. We have shown previously that corneal inoculation of mice with HSV-1 causes acute spontaneous behavioral and electrophysiological seizures and increases hippocampal excitability and kainite-induced seizure susceptibility. In this study, we aimed to determine whether early-life HSV-1 infection in mice might cause short- and long-term enhanced susceptibility to pentylenetetrazol (PTZ)-induced seizures and to evaluate whether early antiviral drug therapy was effectively ameliorating this deficit. Seizure threshold was calculated by the latency of onset of the myoclonic jerk, generalized clonus, and maximal tonic-clonic convulsion. We demonstrate that the localization of viral antigens was predominantly within the bilateral temporal areas (amygdala, piriform, and entorhinal cortex) of HSV-1-infected mice. We also present evidence that mice of all HSV-1-infected groups had a shorter latency and higher severity to PTZ-induced seizures than in age-matched, mock-infected controls. Treatment of HSV-1-infected mice with valacyclovir, a potent inhibitor of HSV-1 replication, produced a dose-dependent decrease in the signs of neurological deficits, pathological damages, and PTZ-induced seizure severity. Our results are consistent with the hypothesis that early-life HSV-1 infection leads to persistent enhancement of neuronal excitability in limbic circuits, which could result in an overall increased propensity to induce seizures later in life. Additionally, prompt optimal antiviral therapy effectively decreases seizure susceptibility in HSV-1-infected mice by limiting the level of viral replication and inflammatory response induced by virus. The present study provides not only experimental evidence, but also a new therapeutic strategy in HSV-1-associated human epilepsy.

Further evidence from a murine infection model that famciclovir interferes with the establishment of HSV-1 latent infections

Mice were infected with herpes simplex virus type 1 (HSV-1) via the ear pinna. Famciclovir therapy was commenced on days 2-7 post infection (p.i.). The ipsilateral and contralateral trigeminal (TG) and third cervical ganglia (CIII) from individual mice were tested for latency 1 and 6 months after infection by explant culture or in situ hybridization for latency-associated transcripts (LAT). There were significantly fewer LAT-positive neurons in ipsilateral and contralateral TG (but not CIII) when therapy was delayed by up to 6 days. There was a low correlation between the number of LAT-positive neurons and reactivation by explant culture. Latency data for individual ganglia, compared with those from previous studies, allow us to rationalize differences between the effects of nucleosides on the establishment of latency in different anatomical sites and when tissues are evaluated using different techniques. The implications of the findings for the use of famciclovir to counter HSV latency in humans are addressed.

Prevention of herpes simplex virus infection and latency by prophylactic treatment with acyclovir in a weanling mouse model

OBJECTIVE

Acyclovir is an antiviral agent that inhibits acute herpes simplex virus replication and decreases the frequency of reactivation, but it is not currently used to prevent primary disease or the establishment of latency. The purpose of this study was to reexamine the efficacy of acyclovir in preventing acute and latent herpes simplex virus infection.

STUDY DESIGN

Mice were infected by footpad inoculation with 2 viral recombinants that express beta-galactosidase. Half of each group was treated prophylactically with intraperitoneal acyclovir and then given acyclovir in the drinking water. Four days after infection, the dorsal root ganglia were removed, fixed, and stained, and the number of cells expressing beta-galactosidase were counted.

RESULTS

Compared with placebo, prophylactic acyclovir completely inhibited acute viral replication as evidenced by the absence of beta-galactosidase activity (P < .001) and significantly decreased the number of neurons harboring latent infection (P = .01).

CONCLUSION

Acyclovir prophylaxis prevented acute and reduced latent ganglionic infection with herpes simplex virus in a weanling mouse model.

Famciclovir and valaciclovir differ in the prevention of herpes simplex virus type 1 latency in mice: a quantitative study

Famciclovir (FCV) and valaciclovir (VACV) have previously been shown to be potent inhibitors of herpes simplex virus type 1 (HSV-1) in a murine cutaneous model. In the present study, mice were inoculated in the skin of the left ear pinna with herpes simplex virus (HSV) type 1. Antiviral therapy was started on different days postinoculation (p.i.), terminating at the end of day 10 p.i. The compounds were administered twice daily by oral gavage at 50 mg/kg of body weight/dose. Mice were sampled on day 5 p.i., during the acute phase of the infection, and the titers of infectious virus in the target tissues (ear, brain stem, and trigeminal ganglia) were determined. At 2 to 3 months p.i., the ipsilateral and contralateral trigeminal and cervical dorsal root ganglia were explanted, and four different methods were used to detect latent HSV. The methods were (i) conventional explant culture for 5 days followed by homogenization, (ii) long-term culture (up to 73 days) of whole ganglia, followed by homogenization, (iii) dissociation by enzymatic disaggregation and an infectious center assay, and (iv) in situ hybridization to detect latency-associated transcripts (LATs). The conventional explant culture method was the least sensitive method, while in situ staining for LAT was the most sensitive, and all mice, including those treated from early times with FCV, were shown to be latently infected. Significantly less latent virus was detected by all four methods, however, in ganglia obtained from mice that had been treated with FCV in comparison with the amount detected in ganglia from mice that had been treated with VACV. However, in no case was latency completely eliminated.

Effect of 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, on clinical recurrences of ocular herpetic keratitis in squirrel monkeys

9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG) is a new viral thymidine kinase inhibitor that we tested for the ability to prevent recurrences of herpetic keratitis. Eighteen squirrel monkeys (Saimiri scuireus) were infected in both corneas with the Rodanus strain of herpes simplex virus type 1 (HSV-1). All corneas showed typical dendritic keratitis 3 days after infection, followed by spontaneous healing. On day 21, the monkeys were randomized into two coded groups and ocular examinations were begun. One group received intraperitoneal (i.p.) injections of HBPG, 150 mg/kg, in a corn oil suspension every 8 h, and the other group received i.p. injections of the corn oil vehicle only. On day 22, recurrences were induced by reducing the temperature of the room in the late afternoon so that a low of 18 degrees C was achieved during the night. After the morning treatment, room temperature was raised to the normal ambient temperature (24-27 degrees C), and treatment was discontinued. Treatment was reinstituted on day 27, the room temperature was lowered again on day 28, and treatment was again discontinued as before. Third and fourth cycles of treatment and cold stress were begun on days 34 and 69. Ocular examinations were continued until day 73, at which point the code was broken. We found that the HBPG treatment significantly reduced the number of corneas with recurrences during the treatment periods, compared with recurrences in untreated, cold-stressed animals (P = 0.01).

Recrudescence of herpes simplex virus type 1 in latently infected rats after trauma to oral tissues

Tooth extraction in rats was used to trigger a latent HSV-1 infection. HSV-1 was inoculated unilaterally in the rat palates. Eight weeks later two molars were removed bilaterally. The trigeminal ganglia were co-cultivated and HSV-1 was isolated from 63% of the ganglia on the infected sides but from only 11% on control sides. The immune response pattern was analysed by immunoblotting of rat serum, and strong reactivity to HSV-1 specific cell polypeptides and glycoproteins (ICP6, gC, pgC, gD) was seen after reactivation. The extraction sockets were histopathologically evaluated and showed healing on the infected side in 26% compared to 63% in contralateral control sockets. The effect of acyclovir (ACV) treatment was elucidated and was found to influence the subsequent development of antibodies and to promote healing of the sockets. Vesiculation in intra- and subepithelial tissue was present on the infected side in 58% but in only 12% of ACV-treated animals. The present study in rats has shown that a latent HSV-1 infection can be established and reactivated by tooth extraction. Reactivation resulted in delayed healing of sockets on the latently infected side but not on the contralateral control side. HSV-1 reactivation was demonstrated serologically by immunoblotting. Healing was significantly promoted by administration of ACV, which also supports the contention that HSV-1 interferes with the healing process.

Primary herpes simplex virus (type 1) infection delays healing of oral excisional and extraction wounds in the rat

The effect of acute herpes simplex virus type 1 (HSV-1) infection on the healing process of intraoral wounds and tooth extraction sockets in the rat was studied. A standardized size of the buccal mucosa was excised and molars were extracted and a HSV-1 suspension was topically applied. The virus infected wounds were clinically characterized by erythema and swelling and histologically by heavy inflammation cell infiltrate and abscesses during the first week. The acute HSV-1 infection was found to significantly delay healing of both types of wounds by 3 days. Antiviral treatment with acyclovir (ACV) decreased the degree of inflammation and improved healing of the infected wounds. The present results indicate a delayed and disturbed healing of wounds in the oral cavity in the presence of HSV-1. The findings may have a clinical significance for primary or latent HSV-1 infections in conjunction with surgical intervention in the oral cavity.

Evaluation of antiviral treatments for recurrent herpes simplex labialis in the dorsal cutaneous guinea pig model

Recurrent herpes simplex labialis has proved to be a difficult disease to treat. Despite 25 years of clinical research with established antiviral substances, only small benefits from experimental therapies have been demonstrated. Progress has been slow, in part, because of the time-consuming nature of large, patient-initiated clinical trials. The dorsal cutaneous guinea pig model is a rapid and efficient means to identify topical antiviral formulations with clinical promise. The cumulative results of our studies with 19 different test treatments show that 8 were equal in efficacy to 5% acyclovir ointment, one was worse and ten were better. Two of the treatments found to be better than 5% acyclovir ointment have been studied clinically, with limited but encouraging results. Differences between the guinea pig model and the human illness mandate caution in predicting the degree of clinical efficacy from experimental outcomes. An effective and conservative use of the model is to optimize the topical formulation of a single antiviral substance.

Effects of combined use of acyclovir and antibody in athymic nude mice inoculated intracutaneously with herpes simplex virus

Antiviral effects of acyclovir (ACV) and antibody were studied in athymic nude mice inoculated intracutaneously in the midflank with herpes simplex virus type 1. Three hours after virus inoculation, treatment was initiated. In ACV-treated mice, the development of skin lesions was inhibited and the mean survival time was prolonged as compared with controls. Treatment with ACV markedly reduced the viral titers both at the inoculation site and in the neural tissues (dorsal root ganglia, spinal cord and brain). Transfer of antibody was also effective in controlling infection as described previously. The use of ACV plus antibody was more effective than the use of ACV alone and in 5 of 17 mice the disease was completely inhibited. Furthermore, in the mice that survived, latent infections in the ganglia were also prevented. These results indicate that treatment with ACV plus antibody is highly effective against herpes simplex virus infection in the immunocompromised host.

Experimental development of herpes simplex virus infection in hamster buccal pouch

In the present study, we have developed an intraoral herpes simplex virus type 1 (HSV-1) infection model in the hamster buccal pouch. This animal model could be used for further oral cancer research related to herpes simplex virus infection.

Virus chemotherapy: antiviral drugs and interferon

Early antiviral drugs, such as idoxuridine and vidarabine, are less effective than newer drugs, such as trifluorothymidine and acyclovir. However, trifluorothymidine is less subject to the development of drug-resistant strains and can be administered topically as a clear drop, which increases patient compliance. Acyclovir has low toxicity and is selective for virus-infected cells because it must be phosphorylated by the viral thymidine kinase to become active. However, drug-resistant strains are produced relatively easily in vitro and may also develop in man with long-term use. To date, no antiviral drug alone has been shown to be effective in the treatment of stromal disease, and no antiviral drug is able to eradicate virus latent in the ganglia and thereby prevent recurrent herpetic infections. Combinations of antiviral drugs and antiviral drugs and interferon are being tested for enhanced efficacy in the treatment of ocular herpetic disease, and for prophylactic effects. The development of recombinant interferons has reduced cost and increased availability, but the effects of the 'manufactured' interferon are not identical to those of natural human leukocyte interferon in all experimental situations.

Recurrences after first episodes of genital herpes in patients treated with topical acyclovir cream

The effect of topical acyclovir treatment of first episode genital herpes on the time to first recurrence in a group of 42 patients receiving either acyclovir or placebo was investigated. Topical acyclovir treatment had no effect on time to first recurrence in patients with either first episode HSV-1 or HSV-2 infections. There was no significant difference in the time to first recurrence in patients with either true primary or initial genital infections. However, the time to first recurrence in patients with first episode HSV-2 was significantly shorter than in patients with first episode HSV-1. Acyclovir treatment appeared to have no effect on the development of neutralising antibody in patients with either virus type.

Antiherpes drugs: promises and pitfalls

In recent years several selective antiherpes drugs have been developed which all show great promise for the systemic and topical treatment of herpes simplex virus and varicella-zoster virus infections. These new antiherpes agents include acyclovir, bromovinyldeoxyuridine, fluoroiodoaracytosine and phosphonoformate. Acyclovir has already been licensed for both topical and systemic use, and it is expected that other compounds will follow soon. Although this new generation of antiherpes drugs suffer from some drawbacks, i.e. narrow spectrum of activity, inefficacy during virus latency, and the possible emergence of drug-resistant virus strains, these limitations by no means outweigh the potentials of these drugs in the therapy and prophylaxis of herpesvirus infections in humans.

In vitro effect of (E)-5-(2-bromovinyl)-2'-deoxyuridine, 5'-amino-5-iodo-2',5'-dideoxyuridine and 2-deoxy-D-glucose on latent ganglionic herpes simplex virus infection

(E)-5-(2-Bromovinyl)-2'-deoxyuridine (BVDU) and 5'-amino-5-iodo-2',5'-dideoxy-uridine AIdUrd, blocked the reactivation of latent ganglionic herpes simplex virus in vitro. Furthermore, BVDU, but not AIdUrd, blocked the multiplication of reactivated latent virus and transiently suppressed emergence of reactivated virus from the sensory ganglia after removal of drug from the medium. 2-Deoxy-D-glucose (2-DG) neither prevented the in vitro reactivation of latent virus nor blocked the further multiplication of reactivated latent virus.

Penetration of guinea pig skin by acyclovir in different vehicles and correlation with the efficacy of topical therapy of experimental cutaneous herpes simplex virus infection

Inadequate penetration of antiviral agents through the stratum corneum of the skin may be one of the limiting factors in the topical therapy of recurrent cutaneous herpes simplex virus infections in humans. In vitro studies of the penetration of the nucleoside analog acyclovir (ACV) through guinea pig skin demonstrated a marked increase in drug flux when ACV was formulated in dimethyl sulfoxide (DMSO), compared with water or polyethylene glycol (PEG) as the vehicle. To examine whether the increased transcutaneous flux of ACV effected by DMSO was meaningful in vivo, topical 5% ACV in DMSO was evaluated for the treatment of cutaneous herpes simplex virus infection in guinea pigs and compared with topical 5% ACV in PEG. When compared with infection sites treated with the vehicle alone, ACV in DMSO produced a greater percent reduction than did ACV in PEG in median lesion number (8 versus 58%; P less than 0.001), median lesion area (35 versus 73%; P = 0.001), and median lesion virus titer (21 versus 84%; P = 0.08). We conclude that DMSO is a highly effective vehicle for topical administration of ACV and is superior to PEG in our model. Careful choice of vehicle and consideration of transcutaneous penetration may be important for realization of the full potential of topical antiviral therapy in humans.

Acyclovir. A review of its pharmacodynamic properties and therapeutic efficacy

Acyclovir (aciclovir) is a nucleoside analogue antiviral drug related to cytarabine, idoxuridine, trifluridine and vidarabine. In common with these earlier antivirals, acyclovir is active against some members of the herpesvirus group of DNA viruses. The efficacy of topical acyclovir has been convincingly demonstrated in ocular herpetic keratitis, and in initial and primary initial genital herpes infection, but little or no clinical benefit was seen when non-primary initial genital infections were assessed separately. Acyclovir ointment demonstrated little benefit in recurrent genital herpes but topical acyclovir cream decreased the course of the infection by 1 to 2 days. Orally and intravenously administered acyclovir were beneficial in initial genital herpes infections, and oral therapy shortened the duration of recurrent infections by 1 to 2 days but did not ameliorate pain. In non-immunocompromised patients with recurrent herpes simplex labialis, generally little clinical benefit was seen with the use of topical acyclovir ointment even when therapy was initiated during the prodromal phase, while topical acyclovir cream effected small but significant improvements in the clinical but not the symptomological course of the disease. However, in immunocompromised patients, both intravenous and topical acyclovir shortened the clinical course of herpes simplex virus infections occurring mainly on the lips, oral mucosa and face, and prophylaxis with either oral or intravenous acyclovir suppressed the appearance of recurrent lesions from latent virus for the period of drug administration, but acyclovir did not eradicate latent herpesviruses. In non-immunocompromised patients, intravenous acyclovir was shown to decrease the acute pain of zoster, especially in the elderly, but postherpetic neuralgia was not ameliorated. When immunocompromised patients were studied, intravenous acyclovir inhibited the progression of zoster infections and shortened the healing time and duration of viral shedding in patients with cutaneous disseminated zoster. However, acute and post-herpetic pain were not significantly affected. Well designed controlled studies are underway to establish the efficacy of acyclovir in herpes simplex encephalitis and cytomegalovirus infections in immunocompromised patients, infections due to Epstein-Barr virus, and neonatal herpesvirus infections. Despite some aspects of the drug's use which require further clarification, acyclovir will make a major impact on the treatment of herpesviral infections. Barring unexpected findings with wider clinical use, it will become the agent of choice in several conditions.

Acyclovir treatment of experimental genital herpes simplex virus infections. I. Topical therapy of type 2 and type 1 infections of mice

Intravaginal inoculation of mice with herpes simplex virus (HSV) provides a model infection of genital herpes to determine the effectiveness of potential antiviral agents. topical (intravaginal) treatment with 1% or 5% acyclovir (ACV) in an ointment of gel vehicle initiated 3, 6 or 24 h after inoculation with HSV type 2, significantly inhibited viral replication in the genital tract and usually reduced final mortality. Treatment with 5% ACV initiated 48 or 72 h after infection also reduced vaginal virus titers but did not alter final mortality. When mice were inoculated with HSV type 1 treatment with 5% ACV significantly reduced viral replication in the genital tract when begun as late as 72 h. In HSV-2 infected mice, treatment initiated 3 h but not 24 h after infection prevented the establishment of latent infection in sacral ganglie. These results suggest that topical ACV may be effective antiviral agent for primary genital herpes in humans.

Mode of action of acyclovir triphosphate on herpesviral and cellular DNA polymerases

The effect of 5'-triphosphate of acyclovir (ACV) on DNA polymerases of two human herpes-viruses, herpes simplex virus type-1 (HSV-1) and Epstein-Barr virus (EBV) as well as human cellular DNA polymerases alpha and beta has been examined. Of the enzymes tested, HSV-1 DNA polymerase was the most sensitive to inhibition by acyclovir triphosphate (ACVTP). The EBV DNA polymerase and DNA polymerase beta were less sensitive. ACVTP inhibition was competitive with dGTP with Ki values of 0.03, 0.15, 9.8 and 11.9 microM for HSV-1 DNA polymerase, DNA polymerase alpha, EBV DNA polymerase and DNA polymerase beta, respectively. Substituting a synthetic primer template (dG) approximately 15 x (dC)n for activated DNA template did not alter the pattern of inhibition. In a time course experiment, addition of ACVTP instead of dGTP did not increase DNA synthesis and it appeared to act as a chain terminator in DNA replication catalyzed by either HSV-1 DNA polymerase or DNA polymerase alpha. Although EBV DNA polymerase was less sensitive to ACVTP inhibition, the nucleoside analog itself was inhibitory to EB virus production by P3HR1 cell line as determined by a reduction in the percentage of cells expressing virus capsid antigen (VCA). On day 4, ACV at 10 and 25 micrograms/ml reduced the cell growth by 10% and 32%, respectively, while it reduced the VCA-positive cells by 80% and 84%, respectively. These results indicate that inhibition of EBV DNA polymerase activity by ACVTP may not be the primary mechanism responsible for ACV inhibition of EBV replication.

Acyclovir treatment of experimental genital herpes simplex virus infections

Genital herpes simplex virus type 2 (HSV-2) infections in mice and guinea pigs were used to determine the effectiveness of acyclovir administered topically, orally, or parenterally. Topical treatment with 1 percent or 5 percent acyclovir begun six or 24 hours and 5 percent acyclovir begun 48 or 72 hours after intravaginal inoculation of mice with HSV-2 significantly inhibited viral replication in the genital tract. Oral administration of acyclovir resulted in a significant reduction in vaginal virus titers when therapy was begun as late as 72 hours after infection. Topical treatment with 5 percent acyclovir initiated 24, 48, or 96 hours after intravaginal inoculation of guinea pigs with HSV-2 significantly altered lesion severity and virus titers but not vaginal HSV titers. Oral acyclovir therapy begun 24 or 48 hours after infection also significantly reduced the mean lesion score and prevented their development in some animals. Lesion and vaginal virus titers were only partially reduced. Intramuscular administration of acyclovir begun on day 2 or day 4 of infection significantly reduced the mean lesion scores but failed to alter lesion or vaginal virus titers.

Acyclovir and vidarabine monophosphate: comparison of iontophoretic and intravenous administration for the treatment of HSV-1 stromal keratitis

We determined the therapeutic efficacy of iontophoretic application of acyclovir and vidarabine monophosphate (ara-AMP) for the treatment of herpes simplex virus (HSV) type 1-induced stromal keratitis in rabbits. The therapeutic efficacy of intravenous administration of acyclovir was assessed in the same model. Stromal keratitis was produced by intrastromal injection of 10 microliters purified HSV-1, McKrae strain. Treatment began the first day after intrastromal injection. Iontophoresis (0.5 mAmp for four minutes) of 3.4 percent (0.1 M) ara-AMP and 5.0 percent (0.22 M) acyclovir was performed once daily for five consecutive days in two treatment groups. Intravenous administration of 50 mg acyclovir/kg was performed twice daily for eight consecutive days. Intravenous administration of NaCl (0.14 M) and ocular iontophoresis of NaCl (0.14 M) were performed as controls in the two treatment groups. At least two scorers performed a single masked evaluation of the disease severity (lesion scoring) of the conjunctiva, corneal epithelium, stroma, and iris by still lamp examination. The eyes were scored daily for 12 consecutive days, and then every other day up to day 22. Iontophoresis of acyclovir or ara-AMP significantly reduced the course of the disease compared with iontophoresis of NaCl. Intravenous administration of acyclovir significantly reduced the disease compared with intravenous NaCl. This suggests that iontophoresis of acyclovir or ara-AMP either alone or in combination with intravenous administration of acyclovir may be of value in the treatment of HSV-1 stromal keratitis.

Effect of acyclovir on genital infection with herpes simplex virus types 1 and 2 in the guinea pig

The pathogenesis of genital infection with three different strains of herpes simplex virus type 1 (HSV-1) and three strains of herpes simplex virus type 2 (HSV-2) was compared in the guinea pig. Strain differences in severity of clinical disease and mortality were noted. HSV-1 strains generally produced milder disease than HSV-2. Both HSV-1 and HSV-2 infections resulted in acute and chronic changes in the cervix. Virus recovery during latent infection was more frequently obtained from the spinal cord in HSV-1-infected animals and from lumbosacral ganglia in HSV-2-infected animals. Systemic treatment with acyclovir, after the onset of clinical disease, had minimal, if any, effect on genital infection with HSV-1 (NYU-78), but similar treatment of HSV-2 (WT-186) infection resulted in decreased lesion scores, paralysis, and mortality during acute infection. A reduction in virus isolations from lumbosacral ganglia was noted during both acute and latent infection with HSV-2 (WT-186) in the acyclovir-treated groups.

Effect of acyclovir, bromovinyldeoxyuridine, vidarabine, and L-lysine on latent ganglionic herpes simplex virus in vitro

Vidarabine and L-lysine did not prevent the in vitro reactivation of latent herpes simplex virus or block the further multiplication of reactivated latent virus. Acyclovir and bromovinyldeoxyuridine both blocked the reaction and the multiplication of reactivated latent virus, and transiently suppressed but did not eliminate latent virus from the sensory ganglia.

Development of oral HSV-1 infection model in mice. Evaluation of efficacy of 5'-amino-5-iodo-2',5'-dideoxyuridine

We developed a new model of oral HSV-1 infection in mice. After oral inoculation, 100 percent of mice developed the clinical lesions at the inoculated area and latent HVS infection in their trigeminal ganglia without mortality. The antiherpetic efficacy of AIdUrd, an agent specifically activated by herpesvirus-encoded enzyme, has been evaluated in this animal model. Early topical or systemic treatment of AIdUrd notably reduced the development of clinical lesions and the virus content in the inoculated lips. However, the establishment of latent HSV infection in the sensory ganglia was not influenced by AIdUrd treatment.

Effect of acyclovir and interferon on human hematopoietic progenitor cells

Continuous in vitro exposure of human bone marrow cells to acyclovir (approximately 200 microM) or human leukocyte interferon (approximately 250 U/ml) caused 50% inhibition of granulocyte colony-forming cell differentiation. Colonies expressed in the presence of either agent were reduced both in size and number. Erythroid progenitors were more resistant than granulocyte progenitors to the antiproliferative effects of acyclovir. Progenitor cells of patients recovering from cytotoxic chemotherapy were no more sensitive to the effects of acyclovir or interferon than were cells obtained from patients before chemotherapy.

Acyclovir and vidarabine in the treatment of ulcerative herpes simplex keratitis

In a masked controlled study, we treated 41 patients who had active herpes simplex corneal ulcers with either 3% acyclovir of 3% vidarabine ointment five times daily for 14 days. There was no statistically significant difference between the two drugs with reference to mean healing time, efficacy of healing, development of stromal keratitis or iritis, post-treatment visual acuity, or adverse reaction.

Acyclovir therapy of neonatal herpes simplex virus type 2 infections in rabbits

New Zealand white rabbits less than 30 h old were inoculated subcutaneously with 10(3) 50% tissue culture infectious doses of type 2 herpes simplex virus. The animals were randomly assigned to a treatment schedule of daily intraperitoneal injections of acyclovir, beginning on the day of virus inoculation for 6 or 12 days, on post-inoculation day 1 for 6 days, or on post-inoculation day 2 for 6 days. The acyclovir was given in doses of 50 mg/kg of body weight per day. Similarly infected animals receiving daily intraperitoneal injection of Eagle minimum essential medium served as controls. All of the control animals died on day 4 or 5 after inoculation. At death they exhibited severe skin lesions, viremia, and dissemination of virus in various visceral organs and spinal as well as trigeminal ganglia. In contrast, animals treated with acyclovir failed to develop significant skin lesions, and death did not occur while treatment continued. Termination of treatment after 6 days resulted in late-onset fatal disease and virus isolation from the brain in many rabbits regardless of the treatment schedule. No such late fatality was observed and no virus could be detected from the brain when treatment was initiated on the day of virus inoculation and continued for 12 consecutive days. With respect to all of the variables studied, treatment for 12 days beginning on the day of virus inoculation was most effective.

Acyclovir treatment of experimental simian varicella infection of monkeys

Replication of simian varicella virus (SVV) in Vero cell cultures was inhibited by acyclovir, 9-(2-hydroxyethoxymethyl)guanine (ACV), at a concentration of 10 micrograms/ml in culture medium. Intravenous administration of ACV at 10 mg/kg twice a day for 10 days or 15 mg/kg three times a day for 5 days to patas monkeys (Erythrocebus patas) beginning 48 h after SVV inoculation blocked the appearance of rash and other clinical symptoms but did not affect viremia. ACV treatment of African green monkeys (Cercopithecus aethiops) at 10 mg/kg twice a day by intravenous injection beginning 24 or 72 h after SVV inoculation and continuing for 10 days had no effect on clinical symptoms, including the development of rash, or on the appearance of viremia. The minimal therapeutic results could be due to the observation that doses of 10 or 15 mg/kg produced plasma levels of ACV which were lower than 5 micrograms/ml, the concentration that inhibited SVV multiplication in vitro, and decayed rapidly.

Acyclovir prophylaxis of herpes-simplex-virus infections

We conducted a double-blind, placebo-controlled study of acyclovir prophylaxis against infection with herpes simplex virus (HSV) in 20 seropositive recipients of bone-marrow transplants. Acyclovir or placebo was administered for 18 days, starting three days before transplantation. Culture-positive HSV lesions developed during the study in seven of the 10 patients who received placebo. In contrast, no such lesions appeared in the 10 patients who received acyclovir (P congruent to 0.003). None of the patients had evidence of drug toxicity. Five of the patients treated with acyclovir had mild culture-positive HSV infections after cessation of the drug, and two additional patients shed virus without having lesions. Acyclovir appears to be a potent inhibitor of HSV replication. Although acyclovir does no appear to eradicate latent infection, it can provide effective prophylaxis against reactivated infections.

The influence of different modes of immunization on the experimental genital herpes simplex virus infection of mice

Previous investigations, which simulated the usual sequence of the human Herpes simplex virus (HSV) infections, had shown that the oral infection of mice with HSV-1 caused only weak protection from genital infection with HSV-2, although the course of infection was attenuated and lethality diminished. This heterologous, heterotopic model was compared with a homologous, heterotopic and a heterologous, homotopic model. The results did not differ very much, although the homologous immunization protected best from lethal outcome, the homotopic immunization best from local infection. Three different preparations of a killed vaccine from purified HSV-1 virion had little effect on the course of the local infection, although protection from lethal outcome was as good as with live virus. In contrast, a crude UV-inactivated vaccine protected nearly completely from local infection. Latent infection in the lumbosacral ganglia was significantly inhibited by immunization with live virus, but only slightly prevented by killed vaccine. The prevalence of latent infection correlated with the extent of vaginal infection. The results show that neither the viral type nor the inoculation site used for immunization with live virus are very critical. Moreover, they allow the conclusion that generalized type-dependent immune factors seem to be engaged in protection against lethal disease; these may be circulating humoral antibodies. On the other hand, locally induced immune factors (probably cellular) are apparently of prime importance for the protection from acute local and latent ganglionic infection.

Immune responses to labial infection of BALB/c mice with herpes simplex virus type 1

The kinetics of appearance of five humoral antibody responses (micro-neutralization assay [NT], complement fixation [CF], enzyme-linked immunosorbent assay [ELISA], radioimmunoassay [RIA], antibody-dependent cell-mediated cytotoxicity [ADCC]), were compared during labial infection of BALB/c mice with herpes simplex virus type 1 strain Patton. The ELISA/RIA antibody responses were present in most mice by day 5 after infection, at the beginning of the herpetic lip lesions; antibody effective in ADCC showed identical early kinetics. In contrast, NT/CF antibodies were not detected in most mice until day 10, at the time of resolution of the herpetic lip lesions. The humoral immune responses persisted for at least 6 months after infection. The NT and CF responses were closely correlated in time of appearance and titers (r = 0.9), as were the ELISA and RIA responses (r = 0.99). However, there was little correlation between NT/CF and ELISA/RIA responses (r = 0.02). The kinetics of the delayed type hypersensitivity response showed similar kinetics of appearance to the ELISA/RIA/ADCC humoral responses, and peaked similarly, but waned gradually over 2 months. The importance of antibody in protection against labial herpes simplex virus type 1 infection was demonstrated by the ability of passively transferred convalescent serum (that produced a minimum NT titer of 10 in recipient mice) to protect against development of herpetic lesions and death.

Combined antiviral effect of interferon and acyclovir on herpes simplex virus types 1 and 2

Acyclovir and human interferon displayed an additive to synergistic effect in reducing the number of herpes simplex viral plaque-forming units in Vero cells, suggesting a therapeutic potential for such combination therapy.