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The genus Orthobunyavirus are a group of viruses within arbovirus, with a zoonotic cycle, some of which could lead to human infection. A characteristic of these viruses is their lack of antiviral treatment or vaccine for its prevention. The objective of this work was to study the in vitro antiviral activity of nordihydroguaiaretic acid (NDGA), the most important active compound of Larrea divaricata Cav. (Zigophyllaceae), against Fort Sherman virus (FSV) as a model of Orthobunyavirus genus. At the same time, the effect of NDGA as a lipolytic agent on the cell cycle of this viral model was assessed. The method of reducing plaque forming units on LLC-MK2 cells was used to detect the action of NDGA on CbaAr426 and SFCrEq231 isolates of FSV. NDGA did not show virucidal effect, but it had antiviral activity with a similar inhibition in both isolates, which was dose dependent. It was established that the NDGA has a better inhibition 1-h post-internalization (p.i.), showing a different behavior in each isolate, which was dependent upon the time p.i. Since virus multiplication is dependent on host cell lipid metabolism, the antiviral effect of NDGA has been previously related to its ability to disturb the lipid metabolism, probably by interfering with the 5-lipoxigenase (5-LOX) and the sterol regulatory element-binding proteins (SREBP) pathway. We determined by using caffeic acid, a 5-LOX inhibitor, that the inhibition of this enzyme negatively affected the FSV replication; and by means of resveratrol, a SREBP1 inhibitor, it was showed that the negative regulation of this pathway only had action on the SFCrEq231 reduction. In addition, it was proved that the NDGA acts intracellularly, since it showed the ability to incorporate into LLC-MK2 cells. The information provided in this work converts the NDGA into a compound with antiviral activity in vitro against FSV (Orthobunyavirus), which can be subjected to structural modifications in the future to improve the activity.

The added benefit of combining valacyclovir (VACV), an antiviral agent, with etanercept (ETA), an anti-tumor necrosis factor alpha (TNF-α) antibody, for the treatment of herpes simplex virus type 1 (HSV-1) encephalitis (HSE) was evaluated in a mouse model. BALB/c mice were infected intranasally with 1.85 × 104 plaque forming units of HSV-1. Groups of mice received a single intraperitoneal injection of vehicle or ETA (400 μg/mouse) on day 3 post-infection combined or not with VACV (1 mg/ml of drinking water) from days 3 to 21 post-infection. On day 5 post-infection, groups of mice were sacrificed for determination of viral DNA load, detection of ETA in brain homogenates and for in situ hybridization. The survival rate of mice was significantly increased when VACV was administered in combination with ETA (38.5% for VACV vs 78.6% for combined treatment; P = 0.04) although VACV or ETA alone had no significant effect compared to the vehicle. The benefit of combined therapy was still present when treatment was delayed until day 4 post-infection. The viral DNA load was significantly reduced in mice treated with VACV alone (P < 0.01) or combined with ETA (P < 0.05) compared to the uninfected group whereas ETA alone had no effect. These results reinforce the notion that both virus-induced and immune-related mechanisms participate in the pathogenesis of HSE and suggest that potent antiviral agent could be combined with immune-based therapy, such as a TNF-α inhibitor, to improve prognosis of HSE.

The pathogenicity and immunogenicity in mice of WR.cl and WR.c3, two mutants of the Western Reserve (WR) strain of vaccinia virus, mutated in the A33R and B5R proteins of the outer envelope of the virus, respectively, were studied. WR.c1 was the most attenuated virus, WR.c3 was somewhat more pathogenic, while WR was the most virulent of the three. While the WR and the WR.c3 viruses, intranasally inoculated into mice, spread efficiently to the different internal organs of the animal, including the brain, WR.c1 was restricted to the lungs only. Mice, intranasally infected with 500 plaque forming units of the WR, WR.c1, or WR.c3 viruses, were protected against infection with a lethal dose of the WR strain.

The purpose of these studies was to investigate the use of non-invasive electroretinography for the evaluation of retinal disease and its treatment in an ocular murine cytomegalovirus (MCMV) disease model. While under anesthesia, 10(2.6)plaque forming units (pfu) of salivary gland passaged, Smith strain MCMV was injected in the anterior chamber of 6- to 8-week-old severe combined immunodeficiency (SCID) mice. At various times post-inoculation, bright-flash scotopic electroretinogram, viral titer, and histology were obtained from the injected eye. Antiviral therapy was tested using 0.1 and 5mg/kg/day subcutaneous injections of HPMPC (Cidofovir) once daily for 5 consecutive days. In infected animals, the a- and b-waves of the electroretinographic (ERG) signal were significantly reduced as of 10 days post-inoculation when compared to control animals. Therapy with HPMPC 0.1mg/kg/day subcutaneously (s.c.) once daily for 5 consecutive days was able to delay the decrease in ERG wave amplitude and inhibit viral replication, whereas 5mg/kg/day s.c. significantly protected the ERG, completely inhibited viral replication, and maintained ocular viral titer below the limit of detection for up to 17 days post-infection. The reduction of ERG activity during progression of retinal disease correlated well with reduction of disease pathology. ERG recording represents a valuable non-invasive technique to measure the progression of the retinal disease induced by MCMV and the efficacy of antiviral treatment in the ocular MCMV disease model.

N -Methanocarbathymidine (( N )-MCT), a thymidine analog incorporating a pseudosugar with a fixed Northern conformation, exhibits potent antiherpetic activity against herpes simplex virus types 1 (HSV-1) and 2 (HSV-2). This study contrasts the metabolic pathway of ( N )-MCT and the well-known antiherpetic agent ganciclovir (GCV) in HSV-1-infected and uninfected Vero cells. Treatment of HSV-1 infected Vero cells immediately after viral infection with ( N )-MCT profoundly inhibited the development of HSV-1 infection. Using standard plaque reduction assay to measure viral infection, ( N )-MCT showed a potency greater than that of ganciclovir (GCV), the IC 50 s were 0.02 and 0.25 μM for ( N )-MCT and GCV, respectively. ( N )-MCT showed no cytotoxic effect on uninfected Vero cells (CC 50 >100 μM). Dose and time dependence studies showed high levels of ( N )-MCT-triphosphate (( N )-MCT-TP), and GCV-triphosphate (GCV-TP) in HSV-1-infected cells incubated with ( N )-MCT or GCV, respectively. In contrast, uninfected cells incubated with ( N )-MCT showed elevated levels of ( N )-MCT-monophosphate only, while low levels of mono, di- and triphosphates of GCV were found following incubation with GCV. Although the accumulation rate of ( N )-MCT and GCV phosphates in HSV-1-infected cells were similar, the decay rate of ( N )-MCT-TP was slower than that of GCV-TP. These results suggest that: (1) the antiviral activity of ( N )-MCT against herpes viruses is mediated through its triphosphate metabolite; (2) in contrast to GCV, the diphosphorylation of ( N )-MCT in HSV-1- infected cells is the rate limiting step; (3) ( N )-MCT-TP accumulates rapidly and has a long half-life in HSV-1-infected cells; and (4) HSV-tk catalyzed the mono, and diphosphorylation of ( N )-MCT while monophosphorylating GCV only. These results provide a biochemical rational for the highly selective and effective inhibition of HSV-1 by ( N )-MCT.

Persistent infections with a cardiotropic enterovirus, e.g. coxsackievirus B2 (CVB2), cause chronic myocarditis and eventually congestive heart failure. Therefore, the antiviral activity of WIN 54954, a capsid binding antiviral agent that inhibits enterovirus uncoating, was studied in persistently CVB2-infected cultures of human myocardial fibroblasts. Cultures displayed a typical carrier state infection with virus titers of 3.9 +/- 1.6 x 10(5) plaque forming units (PFU)/ml and 0.99% infected cells. WIN 54954 (0.025-1 microg/ml) application was started 7 days after infection of the cultures. Compared to the WIN 54954 concentration resulting in a 90% plaque number reduction (EC90 = 0.197 microg/ml) in acutely infected Vero cells, WIN 54954 reduced virus yields of myocardial fibroblast cultures more efficiently, e.g. more than 100 fold (99%) with 0.025 microg/ml after 4 days of application. Antiviral effects of WIN 54954 increased with application time and at 0.025 microg/ml Win 54954 completely inhibited infectious virus progeny after 16 days. Increasing the WIN 54954 concentration up to 1 microg/ml did not cause a greater inhibition of virus replication. In situ hybridization demonstrated that at 0.1 microg/ml WIN 54954 reduced the number of infected cells from 0.99 to 0.18%, although a complete eradication of CVB2-infected cells was not achieved at concentrations as high as 1 microg/ml. In conclusion, the results indicate that low concentrations of WIN 54954 are effective in treating persistent enterovirus infections of myocardial fibroblasts, although a complete eradication of the infection is not achieved with WIN 54954 as a single antiviral agent.

A genital HSV-2 infection of guinea pigs and a cutaneous HSV-1 infection in mice were used to examine the ability of antioxidant components CRT1 to reduce lesion development, duration, and severity. CRT is a patented antioxidant formulation developed by Warner-Lambert Worldwide Consumer Healthcare R. and D. CRT contains three components that work synergistically: vitamin E, sodium pyruvate and membrane stabilizing fatty acids. The MS strain of HSV-2 was utilized for intravaginal inoculation of guinea pigs with approximately 1.2 x 10(5) plaque forming units. The guinea pigs were treated on the external genital skin four times daily for 10 days beginning 48 h post viral inoculation. This study was designed to optimize the CRT formulations that would be used to quantify the synergistic effect of the CRT components. SKH-1 male hairless mice were inoculated with 1 x 10(7) HSV-1 (McIntyre strain) on the dorsal surface of the mouse and treated with CRT formulations starting on the afternoon of the day of infection, and treated for the following 14 days. In the guinea pig model, the CRT formula that contained all three CRT components, worked synergistically to reduce lesion development, duration and severity scores significantly compared to vehicle control or acyclovir. Acyclovir was the only compound that reduced viral titers, but in contrast to CRT, acyclovir did not reduce lesion development, duration or severity. The quantitative effect of the three CRT components was demonstrated in the mouse model.

Laninamivir, a potent neuraminidase (NA) inhibitor, is an active metabolite of laninamivir octanoate (code name: CS-8958) which is a long acting NA inhibitor and is commercially available under the brand name Inavir in Japan to complete the treatment of influenza by a single inhalation. It is supposed that the long acting character is provided by the long retention of laninamivir in the respiratory tract after intranasal administration of laninamivir octanoate in mice and with stable binding of laninamivir to NA of various influenza viruses such as N1, N2 subtypes and NA of B virus. Peramivir, another NA inhibitor, is also approved in Japan as a single intravenous infusion. In spite of the quick disappearance of peramivir from the blood after injection, the reason treatment can be completed by a single administration is thought to be that peramivir showed stable binding to NA with N9 subtype. Therefore, the stable binder, laninamivir is possibly effective by a single intravenous administration in the mouse model infected with influenza viruses. A single intravenous administration of laninamivir and peramivir at 30mg/kg significantly prolonged mice survival at a comparable level in the mouse lethal model infected with the A/PR/8/34 (H1N1) virus. Also, a single intravenous administration of laninamivir and peramivir significantly suppressed virus proliferation in the lungs of mice infected with influenza B virus. Thus, laninamivir may be effective by a single intravenous infusion in treating influenza, the same as peramivir.

Radiation inactivation of viral pathogens has potential application in sterilization and in the manufacture of biological reagents, including the production of non-infectious viral antigens. Viral inactivation by gamma radiation has been extensively investigated, but few direct comparisons to other qualities of radiation have been explored. Experiments were designed to examine direct radiation damage by both gamma photons (gamma) and neutrons (n) while minimizing methodological differences. Frozen samples of influenza A X31/H3N2 and PR8/H1N1 were exposed to gamma and n at doses between 0 and 15.6 kGy. Other experimental parameters, including dose-rate, were not varied. Virus titers were determined by tissue culture infectious dose (TCID(50)) and plaque forming unit (PFU) assays. D(10) values, kGy per log reduction, were calculated from these assays. PR8 D(10) values based on PFU assays were approximately 2 and 5 kGy for gamma and n exposures, respectively, and those based on TCID(50) were approximately 6 and 14 kGy. Similar results were obtained for the A/X31 strain. The data demonstrate that gamma was 2-3-fold more effective than n, with a relative biological effectiveness (RBE) range of 0.43-0.65. These neutron results are likely the first reported for a medically relevant virus. PAGE analysis of viral proteins and RNAs failed to show macromolecular damage. D(10) values were found to be similar to a broad summary of previously reported gamma inactivation values for other virus types. The dependence of the magnitudes of D(10) on titer assay in this study suggests that more than one titer method should be used to determine if complete inactivation has occurred.

A number of new nucleoside analogues with a Z- or E-methylenecyclopropane structure exhibited significant activity against human and murine cytomegaloviruses (HCMV, MCMV) in tissue culture that was generally comparable to, or greater than, 9-[(1-3-dihydroxy-2-propoxy)methyl]guanine (ganciclovir, GCV). Several of these analogues were chosen for further evaluation of therapeutic efficacy utilizing a MCMV infection. Intraperitoneal (i.p.) inoculation of 3-week-old Balb/c mice with 2.0 x 10(5) plaque forming units (pfu) of MCMV results in an acute, lethal infection with rapid virus replication in visceral and glandular tissue, thus, making it an ideal model for identifying compounds that have potential for use in humans. Synadenol (QYL-284A) and synguanol (QYL-438) were administered i.p. once daily for 5 days initiated 6, 24, or 48 h post-viral infection. Significant protection was demonstrated at 50 and 16.7 mg/kg compared to placebo, with efficacy comparable to GCV. When delivered orally once or twice daily at 100 mg/kg per day, QYL-438 was active, but less effective than GCV. In addition, 2-amino-6-methoxypurine analogue (QYL-941) was active at 60 mg/kg administered orally twice daily, comparable to GCV, while it's prodrug (QYL-972) was as effective as GCV at 40 mg/kg when delivered twice daily for 5 days. Additionally, analogue 2-amino-6-cyclopropylaminopurine (QYL-769) was found to be highly efficacious when given orally twice daily for 5 days. Mortality of 0% and 13% was observed at 60 and 20 mg/kg, respectively, which was similar to GCV. Oral treatment with QYL-769 or GCV reduced virus replication in target organs, but neither resulted in complete clearance of MCMV. These data indicate that these new analogues have activity comparable to GCV when given orally to mice and should be evaluated further to assess their potential for use in humans.

Enterovirus 71 (EV71) is the main causative agent of hand, foot, and mouth disease (HFMD) in young children. It has been associated with severe neurological complications and has caused significant mortalities in large-scale outbreaks in Asia. In this study, we demonstrated an enhanced silencing of EV71 through the use of chemically synthesized 29-mer shRNAs. The 29-mer shRNAs were designed to target three highly conserved regions of EV71 genome. Transfection of rhabdomyosarcoma (RD) cells with the 29-mer shRNAs significantly inhibited EV71 replication in a dose-dependent manner as demonstrated by reduction of viral RNA, VP1 protein and plaque forming units. The inhibitory effects were more potent and were achieved at 10-fold lower concentrations when compared to 19-mer siRNAs reported previously [Sim, A.C.N., Luhur, A., Tan, T.M.C., Chow, V.T.K., Poh, C.L., 2005. RNA interference against Enterovirus 71 infection. Virology 341, 72-79]. The viral inhibitory effects lasted 72 h post-infection and there was no adverse off-target silencing effect. Gene silencing by 29-mer shRNAs targeted at the 3D(pol) region (sh-3D) was the most effective, achieving 91% viral inhibition. Further evaluation found that no enhanced inhibitory effects were observed when sh-3D was cotransfected with each of the other two candidates. This study showed an improvement in triggering RNAi using the more potent 29-mer shRNAs, indicating its therapeutic potential against EV71.

N-methylisatin-beta 4':4'-diethylthiosemicarbazone(M-IBDET) and N-allylisatin-beta-4':4'-diallylthiosemicarbazone(A-IBDAT ) inhibit the production of Human Immunodeficiency virus (HIV). Virus inhibition was related to the thiosemicarbazone derivative (TSCD) concentrations and time of treatment. Inhibition of HIV production was confirmed by various parameters of virus assay employing reverse transcriptase activity, plaque forming units (PFU) and levels of viral structural proteins. Effective antiviral TSCD concentrations ranged from 0.17 microM to 2.04 microM for M-IBDET, and from 1.45 microM to 17.4 microM for A-IBDAT. Treatment of the chronic HIV-infected cells for 48 h with 0.34 microM M-IBDET or 2.9 microM A-IBDAT caused about 50% inhibition in as virus yield ED50 as assayed by the PFU method. Almost 2 logs of virus infectivity (PFU) was suppressed after 48 h of treatment with 17.4 microM A-IBDAT. Therapeutic index values of 20 and 30 were found for M-IBDET and A-IBDAT, respectively. A significant selective inhibition of HIV structural protein synthesis was shown by both M-IBDET and A-IBDAT.

Human CMV causes a number of diseases that cause considerable morbidity and that can be life-threatening in immunocompromised patients, particularly those with AIDS. Ganciclovir (GCV) and Foscarnet (PFA) are currently the drugs of choice for management of CMV disease. Both are not without side effects and have a relatively narrow margin of safety. In this report the effects of a human IgG1 neutralizing monoclonal antibody MSL-109 (MSL, Sandoz Pharmaceuticals) on CMV replication was examined both alone or in combination with either GCV or PFA. Human embryonic lung fibroblasts were infected with CMV strain AD169 with a multiplicity of infection of 3 plaque forming units/cell for 1 h. Prior to infection the virus was incubated for 30 min at 37 degrees C with serial concentrations of the MSL Ab (0.1-3.0 micrograms/ml). Concentrations of GCV (0.3 to 30 microM) or PFA (50-400 microM) were added to CMV-infected cells that had been either previously incubated with MSL or not. Four days after infection CMV replication was measured by DNA/DNA probe hybridization using the Hybriwix system. MSL in combination with GCV had an additive effect that was observed at concentrations of GCV of 3-10 microM and MSL of 1-10 micrograms/ml. On the other hand, MSL (3-10 micrograms/ml) together with PFA (100-400 microM) produced a synergistic effect on CMV replication. The data suggest that MSL at doses achievable in humans, enhanced GCV- and PFA-induced antiviral effect in a dose-dependent manner and that the combination might be clinically useful in the treatment of CMV disease.

Using an in vitro system we measured the corneal epithelial cytotoxicity and the antiviral activity of the antiviral agents idoxuridine (IDU), trifluridine (TFT), ethyldeoxyuridine (EDU), and (E)-5-(2-Bromovinyl)-2'-deoxyuridine (BVDU). Confluent rabbit corneal epithelial cell cultures were established, and the antiviral agents were added for 5, 30, or 60 min at a range of concentrations including that used clinically (IDU 0.1%, TFT 1.0%, BVDU 0.1%, EDU 2.0%). Twelve hour [3H]thymidine incorporation then was measured and expressed as % inhibition of control cultures. In separate experiments confluent corneal epithelial cell monolayers were inoculated with 10(4) plaque forming units (PFU) of HSV type 1 (McKrae strain) for 1 h, and IDU 0.1%, TFT 1.0%, and BVDU 0.1% were added to the culture for determination of PFU inhibition. Significant dose-, but not time-dependent, toxicity was observed at the clinical concentrations of IDU, TFT, and EDU. Toxicity was absent for BVDU. TFT and IDU were the most toxic, and EDU was of intermediate toxicity. IDU, TFT, and BVDU showed significant antiviral activity in this corneal epithelial cell culture system (TFT greater than BVDU greater than IDU). The results of this in vitro study paralleled the findings of previous in vivo corneal epithelial toxicity studies of IDU, TFT, and BVDU. Our data, however, suggest that EDU has a potential for clinical toxicity and further studies are recommended. Our model may be useful in the future toxicologic study of new antiviral agents.