Cutaneous infections of mice with vaccinia or cowpox viruses and efficacy of cidofovir

Orthopoxviruses, including smallpox, monkeypox and molluscipox, pose risks to human health through bioterrorist acts or natural transmission. There is no approved therapy for orthopoxvirus infections; however, cidofovir (CDV) has been approved as an investigational new drug for emergency treatment of adverse effects following smallpox vaccination. For evaluation of new therapies directed against orthopoxvirus infections, we have utilized immunocompetent, hairless mice (SKH-1) inoculated by a cutaneous route with cowpox virus (CV) or vaccinia virus (VV). Mice subsequently developed skin lesions and virus was recovered from the site of inoculation and quantified. Skin biopsies were evaluated microscopically, revealing brick-like eosinophilic, intracytoplasmic inclusion bodies characteristic of orthopoxvirus infection. SKH-1 mice fully recovered from either CV or VV infection. Immunodeficient Athymic or Rhino mice inoculated with CV or VV had more lesions and severe disease than SKH-1 mice. CV-infected SKH-1 mice were treated either with systemic or topical CDV. Although some protection was achieved with systemic treatment, 5% topical CDV was most effective at reducing virus titers in skin, lung, kidney, and spleen. These models may provide a means for evaluating efficacy of new therapies directed against orthopoxvirus diseases and further confirm the topical activity of CDV against cutaneous infections.     

Effects of cidofovir on the pathogenesis of a lethal vaccinia virus respiratory infection in mice

Intranasal infection of BALB/c mice with the WR strain of vaccinia virus leads to pneumonia, profound weight loss, and death. Although the major sites of virus replication are in the lungs and nasal tissue, dissemination of the virus to other visceral organs and brain occurs via the blood. In this report the effects of cidofovir on the pathogenesis of the infection was studied. Mice were infected intranasally with virus followed 1 day later by a single intraperitoneal treatment with cidofovir (100 mg/kg) or placebo. Placebo-treated mice were dead by day 8, whereas all cidofovir-treated animals survived through 21 days. Cidofovir treatment did not prevent profound weight loss from occurring during the acute phase of the infection, but the mice gained weight quickly after the 8th day. Significantly higher arterial oxygen saturation levels, as determined by pulse oximetry, were seen in cidofovir-treated animals compared to placebos on days 4-7. Cidofovir treatment markedly improved lung consolidation scores and prevented lung weights from increasing during the infection. Virus titers in lungs and nasal tissue were high starting from the first day of the infection, whereas the titers in liver, spleen, brain, and blood was low for 3 days then markedly rose between days 4 and 6. Lung and nasal virus titers were reduced 10-30-fold by cidofovir treatment on days 2, 4 and 6. Virus titers in the other tissues and blood at their peak (day 6) were 30- to >1000-fold less than in tissues of placebos. These results illustrate the ability of a single cidofovir treatment to control the pathogenesis of an acute lethal infection in various tissues during the vaccinia virus infection in mice.     

Efficacy of N-methanocarbathymidine in treating mice infected intranasally with the IHD and WR strains of vaccinia virus

N-Methanocarbathymidine [(N)-MCT] is a newly identified inhibitor of orthopoxvirus replication in cell culture and in mice. Limited published animal studies indicated the compound is effective by intraperitoneal (i.p.) route at 10-100 mg/(kg day). More extensive studies using different treatment regimens in intranasally infected mice were conducted in order to further explore the potential of this compound compared to cidofovir in treating vaccinia virus infections. (N)-MCT was given twice a day for 7 days, whereas cidofovir was administered once a day for 2 days, each starting 24h after virus exposure for most experiments. (N)-MCT was not toxic up to 1000 mg/(kg day) by the i.p. treatment route. Oral and i.p. treatment regimens with (N)-MCT were directly compared during a vaccinia virus (IHD strain) infection, indicating that the nucleoside has good oral bioavailability in mice. Treatments by i.p. route with (N)-MCT (100 mg/(kg day)) reduced lung, nasal, and brain virus titers during an IHD virus infection, but not nearly to the same extent as i.p. cidofovir (100 mg/(kg day)). Treatment with both compounds decreased liver, spleen, and kidney virus titers, as well as reduced lung consolidation scores and lung weights. Onset of treatment could be delayed by 2 days with (N)-MCT and by 3 days with cidofovir, providing significant survival benefit during the IHD virus infection. Against a vaccinia virus (WR strain) infection in mice, i.p. (N)-MCT treatment prevented death at 500 mg/(kg day), which was comparable in activity to i.p. cidofovir (100 mg/(kg day)). Significant reductions in tissue virus titers occurred with both treatment regimens. (N)-MCT could be further pursued for its potential to treat orthopoxvirus infections in humans.     

Preclinical assessment of topical treatments of herpes simplex virus infection: 5% (E)-5-(2-bromovinyl)-2'-deoxyuridine cream

The potential efficacy of topical therapy with (E)-5-w-bromovinyl)-2'-deoxyuridine (BVDU) for cutaneous herpesvirus infection was evaluated in vitro and in guinea pigs. Drug sensitivity testing against herpes simplex virus type 1 strain E115 revealed an ID50 of 0.008 microgram/ml for BVDU and 0.19 microgram/ml for acyclovir (ACV). In vitro drug diffusion studies showed poor penetration of guinea pig skin by BVDU from the cream compared to BVDU from dimethylsulfoxide (DMSO) (0.04 vs. 1.5 microgram/cm2 per h). 5% BVDU cream, 5% BVDU/DMSO, and 5% ACV in polyethylene glycol (PEG) were then compared in the treatment of experimental dorsal cutaneous HSV-1 infection in guinea pigs. Lesion number, total lesion area and virus titer were reduced by all three formulations compared to control sites treated with the corresponding drug vehicles (P less than or equal to 0.01). BVDU cream effected a greater reduction in lesion number (20+ vs. 13%) and total lesion area (40% vs. 28%) than did ACV/PEG and a significantly greater decrease in virus titer (990% vs. 55%, P less than 0.002). BVDU/DMSO was clinically twice as effective as BVDU cream (P less than or equal to 0.01) and reduced lesion virus titers to a similar degree. The results of these studies show that BVDU is a more potent virus-inhibitory agent than ACV in vitro and is superior to topical ACV in vivo when formulated in a simple aqueous cream. The marked efficacy of BVDU/DMSO in the animal model demonstrates the potential of this antiviral if drug delivery is improved.     

Novel Animal Model for Evaluating Topical Efficacy of Antiviral Agents: Flux Versus Efficacy Correlations in the Acyclovir Treatment of Cutaneous Herpes Simplex Virus Type 1 (HSV-1) Infections in Hairless Mice

This report describes the study of a novel animal model for the topical treatment of cutaneous herpes virus infections, with a focus upon the relationship between the dermal flux of the antiviral agent and the effectiveness of the topical therapy. A recently developed (trans)dermal delivery system (TDS) for controlling acyclovir (ACV) fluxes was employed in the treatment of cutaneous herpes simplex virus type 1 (HSV-1) infections in hairless mice. The TDS's were fabricated with rate-controlling membranes to provide nearly constant fluxes of ACV for up to 3 to 4 days. At the end of each experiment an extraction procedure was used to determine the residual ACV, validating the drug delivery performance of the TDS. Virus was inoculated into the skin of the mice at a site distant from the TDS area, and the induced lesion development was evaluated to distinguish between topical and systemic effectiveness of the therapy. In the main protocol, ACV therapy was initiated 0, 1,2, and 3 days after virus inoculation and the lesion development scored on Day 5. The topical efficacies of 1- and 2-day-delayed treatments were essentially the same as that of a 0-day-delayed treatment, while the topical efficacy of a 3-day-delayed treatment was much poorer. Also, in the cases of 0-, 1-, and 2-day-delayed treatments, topical efficacy increased with increasing flux in the range of 10 to 100 µg/cm²-day. When the ACV flux was 100 µg/cm²-day or greater, a maximum 100% topical efficacy was obtained. The results for systemic efficacy were shifted to higher fluxes: approximately 10-fold greater ACV fluxes were necessary to provide efficacy equal to the topical efficacy results. The animals treated with a high ACV flux (350–500 µg/cm²-day) lived significantly longer than those treated with a low ACV flux (10–125 µg/cm²-day) and those of untreated (placebo) animals. Further, their mean survival time decreased with an increase in the time delay for ACV treatment. In contrast, the mean survival time for the animals which received a low ACV flux was similar to that of the control animals and remained unaltered with an increase in the time delay for ACV treatment. The approach developed in this study should be valuable in (a) the screening of new antiviral agents for the topical treatment of cutaneous herpes virus infections and (b) in the optimization of drug delivery systems (i.e., topical formulations).     

Cell line dependency for antiviral activity and in vivo efficacy of N-methanocarbathymidine against orthopoxvirus infections in mice

A novel carbocyclic thymidine analog, N-methanocarbathymidine [(N)-MCT], was evaluated for inhibition of orthopoxvirus infections. Efficacy in vitro was assessed by plaque reduction assays against wild-type and cidofovir-resistant strains of cowpox and vaccinia viruses in nine different cell lines. Minimal differences were seen in antiviral activity against wild-type and cidofovir-resistant viruses. (N)-MCT's efficacy was affected by the cell line used for assay, with 50% poxvirus-inhibitory concentrations in cells as follows: mouse=0.6-2.2 microM, rabbit=52-90 microM, monkey=87 to >1000 microM, and human=39-220 microM. Limited studies performed with carbocyclic thymidine indicated a similar cell line dependency for antiviral activity. (N)-MCT did not inhibit actively dividing uninfected cells at 1000 microM. The potency of (N)-MCT against an S-variant thymidine kinase-deficient vaccinia virus was similar to that seen against S-variant and wild-type viruses in mouse, monkey, and human cells, implicating a cellular enzyme in the phosphorylation of the compound. Mice were intranasally infected with cowpox and vaccinia viruses followed 24h later by intraperitoneal treatment with (N)-MCT (twice a day for 7 days) or cidofovir (once a day for 2 days). (N)-MCT treatment at 100 and 30 mg/kg/day resulted in 90 and 20% survival from cowpox virus infection, respectively, compared to 0% survival in the placebo group. Statistically significant reductions in lung virus titers on day 5 occurred in 10, 30, and 100mg/kg/day treated mice. These same doses were also active against a lethal vaccinia virus (WR strain) challenge, and protection was seen down to 10mg/kg/day against a lethal vaccinia virus (IHD strain) infection. Cidofovir (100mg/kg/day) protected animals from death in all three infections.     

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.     

Treatment of lethal cowpox virus respiratory infections in mice with 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine and its orally active diacetate ester prodrug

The acyclic purine nucleoside analog, 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (S2242) and its orally active diacetate ester prodrug (HOE961) were reported to be potent inhibitors of vaccinia virus replication in cell culture and in infected mice. These compounds were evaluated further, using infections with the related cowpox virus. Against a wild-type (WT) cowpox virus strain in mouse C127I cell culture, 50% effective concentrations (EC(50), determined by plaque reduction assays) of S2242 and cidofovir (a positive control) were 3.5 and 1.0 microM, respectively. EC(50) values obtained against a cidofovir-resistant strain of the virus were 33 and 230 microM, respectively. Compounds were at least ten-fold less potent against WT virus in Vero cells than C127I cells. S2242 and cidofovir were 50% inhibitory to the proliferation of uninfected C127I cells at 340 and 180 microM, respectively, but neither compound inhibited Vero cell growth at 1000 microM. Mice were lethally infected with cowpox virus by intranasal inoculation, followed 24 h later by antiviral treatment for 5 consecutive days. Once or twice daily intraperitoneal (i.p.) treatments with either S2242 or HOE961 at 100 mg/kg per day resulted in > or = 70 survival compared with no survivors in the placebo group. Lower doses of these compounds (10 and 30 mg/kg per day) were not protective, however. Cidofovir was 100% protective at 30 mg/kg per day. A 10-day course of treatment gave comparable survival results and demonstrated the oral efficacy of HOE961. Treatments with S2242 (100 mg/kg per day) and cidofovir (30 mg/kg per day) each reduced lung and nasal virus titers by approximately ten-fold, whereas, HOE961 (100 mg/kg per day) was less active. Overall, S2242 and HOE961 were found to be effective against cowpox virus infections in mice but were less potent than cidofovir. Since, HOE961 was orally active, it may have advantages over the other parenterally administered compounds for treating orthopoxvirus infections.     

Pilot study using topical imiquimod 5% cream in the treatment of nodular basal cell carcinoma after initial treatment with curettage

BACKGROUND: Nodular basal cell carcinoma (nBCC) is the most common cutaneous malignancy and studies assessing the use of topical imiquimod 5% cream as a monotherapy in the treatment of nBCC have resulted in less than optimal clearance rates. OBJECTIVE: This pilot study was designed to evaluate the efficacy of imiquimod 5% cream on nodular basal cell carcinoma lesions after initial treatment with curettage. METHODS: After obtaining informed consent, 17 nBCCs on 15 patients were included in this institutional review board-approved, open-label study with initial treatment using curettage without electrodesiccation followed by once-daily application of imiquimod 5% cream 5 times per week for 6 weeks. The area was excised and examined histologically 6 weeks after cessation of imiquimod cream. RESULTS: All 17 lesions (100%) showed no histologic evidence of residual tumor on the post-treatment excision. Local site reactions necessitating a rest period from medication application were experienced by most patients (67%), but the majority of patients stated that they would choose this treatment modality over excision if they developed a subsequent tumor. CONCLUSION: Imiquimod 5% cream appears to be an effective treatment method for nodular basal cell carcinoma if combined with curettage prior to application.     

Bowen's disease of the penis treated with topical imiquimod 5% cream

Bowen's disease of the penis is relatively uncommon, but the prevalence has increased in recent years. Risk factors for penile squamous cell cancer include smoking, infection with human papilloma virus (HPV), immunosuppression, and a history of conditions such as balanitis, phimosis, and lichen sclerosis et atrophicus. Bowen's disease of the penis is often managed by local excision of the lesion. Less invasive methods are now employed more frequently and include laser ablation, electrodessication and curettage, cryosurgery, application of5-fluorouracil, and topical imiquimod 5% cream. This case report describes the successful treatment of Bowen's disease of the penis with topical imiquimod 5% cream in a 42-year-old African American male with human immunodeficiency virus (HIV) disease.     

Safety studies of topical imiquimod 5% cream on normal skin exposed to ultraviolet radiation

BACKGROUND: Imiquimod 5% topical cream is an immune response modifier that induces interferon alpha and interleukin-12, and exhibits antiviral and tumor-inhibiting properties. It is currently available for treatment of genital and perianal warts. Three randomized, open-label or assessor-blinded, placebo-controlled studies were carried out to assess its safety on normal white skin exposed to ultraviolet radiation (UVR). METHODS: Healthy white volunteer adult subjects between the ages of 18 and 60 years with skin types I, II or III (Fitzpatrick Scale, US Federal Register 43:38260, 1978) were invited to participate. Imiquimod 5% cream (each dose approximately 0.1-0.2 ml) was compared with placebo cream. Two preliminary studies assessed the potential photosensitizing properties of the drug, and the third study added measurement of sunburn cell counts (SBC) and deoxyribonucleic acid (DNA) pyrimidine dimer (PD) formation. The three studies were: a 6-week standard photocontact allergenicity bioassay; a 4-day standard phototoxicity bioassay; and a 4-week photodamage study using biopsy sample analyses to determine SBC or PD frequency. RESULTS: Imiquimod had no detectable potential for inducing either photocontact allergy (n=115) or phototoxicity (n=20). The final study further assessing photodamage potential of imiquimod included 44 subjects. There were no significant differences between imiquimod vs. the control (no drug+UVB) for SBC counts (mean 0.88 vs. 0.93), or PD frequency (mean 60.86 vs. 70.03). CONCLUSIONS: Results from the two preliminary safety studies suggest that imiquimod 5% cream does not possess a detectable photosensitizing potential in humans. Furthermore, topical imiquimod did not enhance UVR-induced damage to epidermal cells or DNA.     

Topical imiquimod: a review of its use in the management of anogenital warts, actinic keratoses, basal cell carcinoma and other skin lesions

Topical imiquimod 5% cream (Aldara) is an immune response modulator that is indicated for the treatment of external anogenital warts, superficial basal cell carcinoma and actinic keratoses. The cream is applied two to five times per week for varying periods, depending on the indication. Topical imiquimod cream has also been evaluated in the treatment of several other skin conditions.Immunomodulatory therapy with topical imiquimod 5% is an effective option for the approved indications. The drug appears to be relatively well tolerated, with the option of breaks from treatment as required for local skin reactions (which are common). Systemic reactions have been reported. Treatment of human papillomavirus- and UV-associated skin lesions with topical imiquimod offers a noninvasive, tissue-sparing alternative to ablative treatment options. However, well designed trials of the sustained, long-term efficacy and tolerability of topical imiquimod versus those of common treatment approaches including surgery and other topical alternatives are required before the place of the drug in the management of these lesions can be finalised. Nonetheless, while other treatments for anogenital warts, superficial basal cell carcinoma or actinic keratoses are available, the advantages of self treatment linked with the demonstrated efficacy of topical imiquimod offer an attractive alternative for many patients.     

Antiviral activity of HPMPC (cidofovir) against orf virus infected lambs

(S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]cytosine [corrected] (HPMPC, cidofovir, CDV, Vistide) is an acyclic nucleoside analogue with a potent and selective activity against a broad spectrum of DNA viruses including the poxviruses. In this study we present the results of different treatment regimens in lambs experimentally infected with orf virus with different cidofovir formulations prepared in Beeler basis and Unguentum M. Our results show that choice of excipient, concentration of codofovir [corrected] and treatment regimen were all important to the clinical outcome of the therapy. Whilst one particular regimen appeared to exacerbate the lesion, treatment with 1% (w/v) cidofovir cream, prepared in Beeler basis, for 4 consecutive days did result in milder lesions that resolved in milder lesions that resolved [corrected] more quickly than untreated lesions. Furthermore the scabs of the treated animals contained significantly lower amounts of viable virus meaning there should be less contamination of the environment with virus than would normally occur.     

咪喹莫特在尖锐湿疣治疗中的应用

咪喹莫特是一种局部应用的免疫调节剂 ,可刺激皮肤粘膜产生干扰素、肿瘤坏死因子和白介素 1,6,8,提高细胞免疫应答 ,产生抗病毒效果。5 %咪喹莫特霜治疗尖锐湿疣 ,疣体完全清除率为37%～ 5 0 % ,不良反应为局部轻、中度的瘙痒、红斑、烧灼感、触痛、溃疡、糜烂、疼痛等 ,具有较好临床应用价值。     

Antiviral activity and inhibition of topoisomerase by ofloxacin, a new quinolone derivative

The antiviral activity of ofloxacin, a new quinolone derivative, against vaccinia virus (VV), herpes simplex virus (HSV) and influenza virus (InfV) was evaluated in both in vitro and in vivo experiments. As a result, ofloxacin showed inhibitory activity against VV in cultured mammalian cells, and prevented formation of pox tail lesions in VV-infected mice. However, it was less effective against HSV and InfV than VV. The antiviral activity of ofloxacin assessed by VV tail-lesion test was strongest when administered to mice through the oral route daily for five consecutive days post-infection. Nalidixic acid and novobiocin, well-known gyrase inhibitors, showed only weak antiviral activity in both in vitro and in vivo tests against VV. It was also demonstrated that ofloxacin inhibited virus-specific DNA and RNA syntheses. It was more inhibitory to VV topoisomerase than cellular topoisomerases. Thus, ofloxacin has selectivity for VV.     

Cidofovir in the treatment of poxvirus infections

Cidofovir [(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine, HPMPC] has since 1996 been licensed for clinical use in the treatment of cytomegalovirus (CMV) retinitis in AIDS patients. Cidofovir has broad-spectrum activity against virtually all DNA viruses, including herpes-, adeno-, polyoma-, papilloma- and poxviruses. Among the poxviruses, vaccinia, variola (smallpox), cowpox, monkeypox, camelpox, molluscum contagiosum and orf have proven sensitive to the inhibitory effects of cidofovir. In vivo, cidofovir has shown high efficacy, even after administration of a single systemic (intraperitoneal) or intranasal (aerosolized) dose, in protecting mice from a lethal respiratory infection with either vaccinia or cowpox. Cidofovir has also demonstrated high effectiveness in the treatment of vaccinia virus infection in severe combined immune deficiency mice. In humans, cidofovir has been used successfully in the treatment, by both the topical and intravenous route, of recalcitrant molluscum contagiosum and orf in immunocompromised patients. Taken together, these data indicate that cidofovir should be effective in the therapy and short-term prophylaxis of smallpox and related poxvirus infections in humans, as well as the treatment of the complications of vaccinia that may arise in immunocompromised patients inadvertently inoculated with the smallpox vaccine (vaccinia).     

Treatment of primary herpes simplex virus infection in guinea pigs by imiquimod

Imiquimod (also known as R-837 and S-26308) is an imidazoquinoline immune response modifier and is available in the US and several other countries for the treatment of external genital warts. Imiquimod has no direct antiviral activity but demonstrates efficacy in several animal models of virus infection. The drug is recognized by antigen presenting cells including monocytes, macrophages, B-cells and dendritic cells and induces these cells to produce cytokines including interferon-alpha (IFN-alpha) and others. Imiquimod's ability to inhibit primary lesion development in the guinea pig model of Herpes simplex virus (HSV) intravaginal infection was studied. Imiquimod given intravaginally reduced primary lesions, reduced virus shedding and reduced virus content of spinal cords from HSV infected guinea pigs. A single drug application of 0.5 mg/kg reduced lesion frequency when given between 24 h before inoculation to 16 h after inoculation. A single drug application of 5 mg/kg reduced lesion frequency and severity when administered between 72 h before inoculation to 24 h after inoculation. The antiviral effect resulting from interferon induction in the animal lasts much longer than the drug itself, thus imiquimod is different than drugs having direct antiviral activity. Twice daily drug application for 4 days was effective when initiated up to 72 h after inoculation, however, once lesions began to appear, imiquimod treatment was not able to stop lesion development. Imiquimod treatment inhibited lesion development and/or virus shedding in guinea pigs inoculated with HSV-1, HSV-2 or virus isolates resistant to acyclovir. Imiquimod is currently in clinical trials for treating human HSV infections.     

Treatment of genital herpes in males with imiquimod 1% cream: a randomised, double-blind, placebo-controlled study

OBJECTIVE: The aim of this randomised, double-blind, placebo-controlled study was to examine the clinical significance, efficacy and tolerability of imiquimod 1% cream to manage patients exposed to first episodes of genital herpes. PATIENTS: Male patients (n = 60), ranging in age between 18 and 50 years (mean 25.7 years), presenting for <6 days (mean 4.4 days) with culture-confirmed diagnosis of genital herpes, and bearing a total of 696 lesions (mean 11.6 lesions/ patient), entered the study and were randomised to receive a precoded 40g tube and instructions on how to apply the trial medication to their lesions twice for 5 consecutive days per week. RESULTS: A marked clinical benefit from self-application of imiquimod 1% cream was demonstrated, resulting in both significantly shorter mean duration of healing than with the placebo (5.2 vs 14 days; p < 0.001) and more healed patients [23 of 30 (76.7%) vs 2 of 30 (6.7%); p < 0.0001]. Of the 60 patients, 54 (90%) reported no drug-related adverse effects. Two patients in the imiquimod group reported non-objective mild burning sensation and four experienced a transitory increase in their body temperature (>38 degrees C) accompanied by mild headache and malaise; however, such indications were not severe enough to cause discontinuation of the treatment, and resolved within 24 hours. Treatment was well tolerated by all the patients, with no dropouts. Among 25 healed patients, four had a relapse after 9 months. CONCLUSION: Although the analogue of imiquimod 1% cream demonstrated mild to moderate subjective adverse effects, it was significantly more effective than placebo in treating patients with a first episode of genital herpes. Further clinical studies appear warranted.     

Effects of four antiviral substances on lethal vaccinia virus (IHD strain) respiratory infections in mice

Intranasal infection of BALB/c mice with the IHD strain of vaccinia virus was found to cause pneumonia, profound weight loss and death. Cidofovir, hexadecyloxypropyl-cidofovir (HDP-CDV), the diacetate ester prodrug of 2-amino-7-[(1,3-dihydroxy-2-propoxy)methyl]purine (HOE961), and ribavirin were used to treat the infections starting 24h after virus exposure. Single intraperitoneal (i.p.) cidofovir treatments of 100 and 30 mg/kg led to 90-100% survival compared with no survivors in the placebo group, whereas a 10 mg/kg dose was ineffective. The 100 mg/kg treatment reduced lung and snout virus titres on day 3 of the infection by 20- and 8-fold, respectively. Mean arterial oxygen saturation levels in these two cidofovir treatment groups were significantly higher than placebo on days 4 through 6 of the infection, indicating an improvement in lung function. Effects of cidofovir on viral pathogenesis were studied on days 1, 3 and 5 of the infection, and demonstrated statistically significant reductions in lung consolidation scores, lung weights, lung virus titre and snout virus titres on days 3 and 5. Cidofovir treatment also reduced virus titres in other tissues and body fluid, including blood, brain, heart, liver, salivary gland and spleen. HDP-CDV was given by oral gavage at 100, 50 and 25mg/kg doses one time only, resulting in 80-100% survival. Lower daily oral doses of 10 and 5mg/kg per day given for 5 days protected only 30% of animals from death. Oral doses (100, 50 and 25 mg/kg per day) of HOE961 for 5 days protected all animals, whereas equivalent oral doses of ribavirin were completely ineffective. The rapidity of recovery from weight loss during the infection was a function of dose of compound administered. These data indicate the utility of parenteral cidofovir, oral HDP-CDV and oral HOE961 in treating severe respiratory infections caused by this virus.     

Intranasal treatment of cowpox virus respiratory infections in mice with cidofovir

Orthopoxvirus infections in mice have been effectively treated with cidofovir, a clinically approved drug given by intravenous infusion to treat cytomegalovirus infections. In a bioterrorist scenario it would be technically difficult to give this drug to a large number of exposed individuals. New treatment approaches are being sought, which include giving cidofovir by alternative routes or designing oral prodrugs of cidofovir. In this report, intranasal cidofovir was investigated as a treatment of pulmonary cowpox virus infections in BALB/c mice. Ninety to 100% of animals given a single intranasal drug treatment (10, 20 or 40 mg/kg) 24 h after virus challenge survived the infection, whereas all placebo-treated mice died. Doses of 2.5 and 5 mg/kg resulted in 60 and 80% survival, respectively. Single treatments of 20 and 40 mg/kg could be given up to 3 days after virus inoculation and still be 80-90% protective. A single 40 mg/kg treatment of infected mice given 1 or 2 days after infection also resulted in statistically significant decreases in virus titer in lungs and nose/sinus compared to the placebo group. Drug efficacy was found to be contingent upon treatment volume. A 10 mg/kg intranasal dose given 24 h after virus challenge was 100 and 50% effective in volumes of 40 and 20 microl, respectively. The same dose in 5 and 10 microl volumes caused no decrease in mortality. The results of these studies establish the utility of cidofovir treatment of poxvirus infections in mice by intranasal route. The data suggest the possibility that aerosol delivery of cidofovir to human lungs may be a viable alternative to intravenous dosing.