Earl R. Kern

The natural history of recurrent herpes simplex labialis. Implications for antiviral therapy.

We performed daily examination of 80 patients with recurrent herpes simplex labialis to define the course of the disease and to identify quantitative and objective measurements for use in monitoring the efficacy of antiviral chemotherapy. Pain, lesion size, mean virus titers from lesion swabs (10(5) plaque-forming units [PFU]) and frequency of virus-positive lesions (89 per cent) were maximal during the first 24 hours and decreased thereafter. Lesion punch-biopsy virus titers increased from a mean of less than 10(1) PFU in the prodromal and erythema stages to a mean of 10(4.7) in the vesicle stage. MEasurements potentially useful in monitoring antiviral efficacy include: time to loss of crust, time to complete healing, intensity and duration of lesion pain, area defined by lesion virus titer and duration of lesion virus excretion, and maximum lesion virus titer after the first visit. Early application of topical antiviral therapy should theoretically be able to alter the course of this disease.

Comparison of antiviral and antitumor activity of activated macrophages

Abstract The antiviral and antitumor activity in vitro of normal, stimulated, vaccinia virus “immune”, and activated peritoneal macrophages were compared. Activated (pyran or corynebacteria induced) PEC exhibited both antitumor and antiviral activity. Stimulated (thioglyocollate) and vaccinia virus “immune” PEC inhibited virus growth but did not possess antitumor activity. Normal (unstimulated) PEC were relatively ineffective in either activity. The antiviral activity was nonspecific, being expressed against herpes simplex and EMC viruses in addition to vaccinia. Although a possible role for interferon was suggested by the lack of activity of mouse PEC on vaccinia virus growth in heterologous FLK cells, definitive proof was not obtained. The activity was most pronounced against multiple cycles of viral infection initiated at a low multiplicity of infection. Single cycle virus growth was not affected, suggesting that the major inhibition was on subsequent cycles of virus growth.

Antiviral Activity of Extracts from Marine Algae

Extracts of two species of marine algae, Constantinea simplex and Farlowia mollis, were tested for antiviral activity in tissue culture and in experimental infections of mice. Treatment of confluent mouse embryo fibroblast cell monolayers with either compound before viral inoculation was effective in inhibiting the replication of herpes simplex virus type 1 and type 2, vaccinia virus, and vesicular stomatitis virus, but not encephalomyocarditis virus, Semliki Forest virus, or murine cytomegalovirus. Prophylactic administration of these extracts was effective in reducing final mortality or prolonging the mean day of death of animals inoculated by the intraperitoneal, intracerebral, or intranasal routes with herpes simplex virus type 2. When therapy was initiated after viral inoculation or at a site other than that of viral inoculation, no significant effect on mortality or on mean day of death was observed. Neither preparation was effective in mice inoculated intraperitoneally with encephalomyocarditis virus, Semliki Forest virus, or murine cytomegalovirus or in animals infected intravaginally with herpes simplex virus type 2. The prophylactic but not therapeutic antiviral activity of these preparations seriously limits their potential use in human herpes simplex virus infections.

Alteration of Mortality and Pathogenesis of Three Experimental Herpesvirus hominis Infections of Mice with Adenine Arabinoside 5′-Monophosphate, Adenine Arabinoside, and Phosphonoacetic Acid

The therapeutic effectiveness of adenine arabinoside 5′-monophosphate (ara-AMP), adenine arabinoside (ara-A), and phosphonoacetic acid (PAA) was compared in three experimental Herpesvirus hominis type 2 infections of mice. In animals inoculated with H. hominis by the intracerebral or intraperitoneal route, both ara-AMP and ara-A were highly effective in reducing mortality even when treatment was begun 48 to 96 h after viral inoculation. ara-AMP was the most effective in both models in that treatment could be initiated 24 to 48 h later in the course of infection than with ara-A and still confer significant protection. In mice inoculated intraperitoneally, protection due to ara-AMP therapy was associated with reduced replication of virus in visceral organs and complete inhibition of transmission of virus to the brain. PAA treatment of mice inoculated intraperitoneally was effective in reducing mortality only if initiated shortly after infection. Treatment with PAA did not reduce mortality of mice inoculated intracerebrally but did prolong the mean day of death. When mice were inoculated intranasally with H. hominis, none of the three drugs altered final mortality; however, treatment with ara-AMP did prolong the mean day of death. Treatment with ara-AMP effectively reduced viral replication in the lung and liver in this model infection, but failed to prevent transmission of virus through the trigeminal nerves from the nasopharynx to the brain.

Controlled (trans)dermal delivery of an antiviral agent (acyclovir). I, An in vivo animal model for efficacy evaluation in cutaneous HSV-1 infections

Abstract An in vivo animal model using hairless mice was developed for the study of the dose/flux-efficacy relationship of antiviral agents in cutaneous herpes simplex virus-1 infections. After cutaneous virus inoculation of the mice, acyelovir (ACV), a widely used antiviral agent, was transdermally delivered in a quantitatively controlled fashion. Virus was inoculated into the skin of the mice at a site distant from the dermal patch area and the pattern of the induced lesion development was evaluated in a novel way which enabled the distinction between topical and systemic antiviral drug efficacy. Plots of the antiviral efficacy vs. the drug delivery rate gave typical sigmoidal curves of relatively high reproducibility, thus demonstrating a unique example of a dose/flux-response relationship in local antiviral treatment.

Treatment of a murine cytomegalovirus infection with exogenous interferon, polyinosinic-polycytidylic acid, and polyinosinic-polycytidylic acid-poly-L-lysine complex.

Treatment of a cytomegalovirus infection of mice with exogenous murine interferon did not alter final mortality or mean day of death. Pretreatment with two interferon inducers significantly reduced mortality, but treatment initiated after infection was not effective.

Transmission of cytomegalovirus infection in mice by skin graft

Transmission of infectious disease, including virus, by allogeneic tissue transplants is a major clinical concern. The present study provided evidence for the transfer of murine cytomegalovirus (MCMV) by syngeneic and allogeneic skin grafts transplanted immediately after harvest from acutely infected donor mice. Transfer of MCMV also occurred following skin grafting with cryopreserved syngeneic skin. Recipients of infected skin were first positive for MCMV between 9 and 15 days post transplant, and MCMV was continually detectable through day 30. These results suggest that fresh or banked skin may serve as a source for transmission of cytomegalovirus infections.

A comparison of phosphonoacetic acid and phosphonoformic acid activity in genital herpes simplex virus type 1 and type 2 infections of mice

The activity of phosphonoacetic acid (PAA) and phosphonoformic acid (PFA) against four strains of herpes simplex virus type 1 (HSV-1) and four strains of HSV-2 were compared in tissue culture and in a murine model of genital herpes. In mouse embryo fibroblast cells, both drugs were three-fold more active against the HSV-1 strains than against the HSV-2 strains. In contrast, in the animal model infections, PAA appeared to be more active against the HSV-2 strains, while PFA was equally effective against both HSV types. In mice infected intravaginally with HSV-2 and treated with intravaginal 5% PAA, none of the treated mice became infected, replication of virus in the genital tract was completely inhibited, none of the infected mice died from encephalitis, and latent infection in lumbosacral ganglia of surviving animals was completely prevented. In HSV-1 genital infection treated with PAA, 20-60% of mice became infected, replication of virus in the genital tract was strikingly reduced, none of the infected mice died, and latent infection was completely prevented. In both HSV-2 and HSV-1 genital infections, 20-70% of animals treated with 8% PFA became infected, growth of virus in the genital tract was reduced significantly but not completely suppressed, mortality was variably altered, and there was a trend towards reduction in the frequently of latent infection. These results indicate that HSV-1 strains are more sensitive to PAA and PFA in tissue culture, but the HSV-2 strains are generally more amenable to therapy in the murine model of genital herpes. Although PAA appeared to be more active that PFA in the genital infection, both drugs significantly altered the course of the infection. Since dermal toxicity associated with PAA precludes its use in humans and since PFA is already undergoing trials in patients with recurrent herpes labialis, the current results suggest that topical PFA deserved further evaluation in the treatment of mucocutaneous HSV infections, including genital herpes.

Topical butylated hydroxytoluene treatment of genital herpes simplex virus infections of guinea pigs

The effect of topical treatment with butylated hydroxytoluene (BHT) was evaluated in primary and recurrent genital herpes simplex virus type 2 (HSV-2) infection of guinea pigs. In the first experiment, treatment with placebo, 5%, 10%, or 15% BHT was initiated 48 h after viral inoculation and continued 4 times daily for 15 days. During primary infection no differences in maximum lesion severity or titers of virus in lesions were observed, however, lesion duration was reduced in BHT-treated animals resulting in a significantly smaller lesion score-day area under the curve. In a second experiment using U.S.P. mineral oil as an additional placebo, BHT placebo and 15% BHT in a double blind trial, similar results were obtained. Treatment of the recurrent infection in either experiment failed to alter the number of recurrent episodes or days with lesions.

Animal Models as Assay Systems for the Development of Antivirals

The importance of experimental viral infections in animal models for development and testing of new antiviral agents prior to their use in man should not be understated. While tissue culture systems are of great value in determining if a new drug has activity against a particular virus, these systems should not be used as indicators or predictors of activity in humans. Only where suitable animal models are not available, should a compound be taken from tissue culture directly into human trials. Although one can legitimately argue that most, if not all, animal model infections are not identical to the human disease, it can be demonstrated that a compound does in fact have activity in an in vivo system and early indications of its antiviral activity, tissue distribution, metabolic disposition, pharmacokinetics, and acute toxicity can be realized. Importantly, all of these parameters of drug pharmacodynamics can be correlated with inhibition of viral replication in target organs. Additionally, our understanding of the pathogenesis of many viral infections, the response of the host to infection and interaction between the infection, the host’s response, and a therapeutic agent has been enhanced greatly through the use of animal model systems.