Day Of Virus Inoculation Research Articles

Isolation and genetic characterization of waterfowl parvovirus in ducks in Northern Vietnam.

Short beak and dwarfism syndrome (SBDS), a highly contagious disease, has been reported in duck farms in Vietnam since 2019. In this study, we evaluated the virulence and characterized the virus obtained from SBDS cases in North Vietnam. Polymerase chain reaction was used to detect waterfowl parvovirus in ducks, and the virus from positive samples was inoculated into 10-day-old duck-embryonated eggs to reproduce the disease in young ducklings to determine the virulence and subjected to phylogenetic analysis of non-structural (NS) and VP1 gene sequences. Goose parvovirus (GPV) was isolated from ducks associated with SDBS in Vietnam. The virus Han-GPV2001 is highly virulent when inoculated into 10-day-old duck embryos and 3-day-old ducklings. The mortality rate of duck embryos was 94.35% within 6 days of virus inoculation. Inoculating 3-day-old ducks with the virus stock with 104.03 EID50 through intramuscular and neck intravenous administration resulted in 80% and 66.67% of clinical signs of SDBS, respectively, were shown. Phylogenetic analysis based on the partial NS and VP1 gene sequences revealed that the viral isolate obtained in this study belonged to novel GPV (NGPV) and was closely related to previous Vietnamese and Chinese strains. A GPV strain, Han-GPV2001, has been successfully isolated and has virulence in duck-embryonated eggs as well as caused clinical signs of SBDS in ducks. Phylogenetic analyses of partial genes encoding NS and capsid proteins indicated that the obtained GPV isolate belongs to the NGPV group.

Investigating the Safety and Efficacy of the Synthetic Drug Herbix on Immune Responses Involved in the Treatment of a Mouse Model of Herpes Simplex Virus.

Herpes simplex virus-1 (HSV-1) infections can cause significant harm to individuals, including blindness, congenital defects, genital herpes, and even cancer, with no definitive cure .so, finding new treatment strategies is crucial. In this study, 25 male BALB/c mice were used to conduct a mouse model of herpes by subcutaneously injecting an HSV-1 suspension (100 µL of 1× PFU/mL). The mice were divided into 5 groups with groups 1 to 3 designated as intervention groups, and groups 4 and 5 serving as positive and negative control groups, respectively. After 2 days of virus inoculation, the mice were treated with different concentrations of Herbix (100, 200, and 300 mg/mL) via subcutaneous injection. Mice Blood samples (0.5 to 1 mL) were taken from the mice before and after the experiments, and after three-week follow-up period, the mice were sacrificed and the spleens were removed for lymphocyte analysis. we found that administration of Herbix at a dose of 300 mg/mL showed the greatest efficacy, characterized by a delay in skin lesion formation, an increment in survival rate and lymphocyte proliferation, upregulation of the gene expression of interferon alpha (IFN-α) and tumor necrosis factor alpha (TNF-α), and an increase in the polarization of cytotoxic and helper T lymphocytes compared to the control group. These results suggest that Herbix at a dose of 300 mg/mL is effective in treating murine herpes and stimulating immune responses, making it a potential candidate for further investigation as an antiherpetic drug.

High impact of Clerodendrum paniculatum leaf extract to suppress zucchini yellow mosaic virus infection in zucchini plants

Abstract. Pandawani NP, Listihani L, Widnyana IK, Ariati PEP, Selangga DGW. 2022. High impact of Clerodendrum paniculatum leaf extract to suppress zucchini yellow mosaic virus infection in zucchini plants. Biodiversitas 23: 2914-2919. Zucchini yellow mosaic virus (ZYMV) is an important virus in zucchini plants (Cucurbita pepo L.). ZYMV infection is prevalent in C. pepo in Bali and is extremely difficult to eradicate. This study aimed to determine the efficacy of pagoda leaf extract (Clerodendrum paniculatum L.) in reducing yield loss in C. pepo. A factorial randomized block design with two variables was employed in this study. The application time of the C. paniculatum extract was the first variable, and concentration was the second. Plant extract was applied during seed immersion, one day before and after inoculation, and on the same day of virus inoculation. The concentrations of C. paniculatum extract employed were 10%, 30%, and 50%. The crude extract was sprayed onto the C. pepo leaves. Plants treated with extract one day after virus inoculation at 10%, 30%, and 50% concentrations exhibited yellowing, yellowing with cupping, mosaic, mosaic with cupping, and stunting. While application of extract one day before virus inoculation at 30% and 50% concentrations resulted in yellowing and yellowing with cupping signs. Plants infected with ZYMV first showed flowering at 37 DAP, whereas plants treated with C. paniculatum leaf extract one day before virus inoculation started flowering at 32 DAP. Application of C. paniculatum leaf extract one day before ZYMV inoculation on C. pepo effectively suppressed 40% yield loss. The findings of present investigation revealed information about the potential of C. paniculatum leaf extract as a plant virus control agent through the mechanism of induction in C. pepo.

Evaluation of an in vitro virus culture system of anti-virus study of the Chinese herb

Influenza A virus was selected for anti-virus study with a garlic extract and a Chinese herb, Anoectochilus formosanus Hay. The virus was inoculated into the human promonocyte cell line, HL-CZ, which had been estabished in this laboratory. The infected cells have shown viral antigens detected by immunofluorescence staining with both monoclonal antibodies against virus nucleoprotein (NP) and hemagglutinin (HA) after 1-3 days of virus inoculation. This in vitro virus culture system was used as a tentative model for evaluating anti-virus activity of Chinese herbs. The relative minimum concentration of cytotoxicity (MCC) of the herb preparation to the HL-CZ cells was observed and determined during 7 days of cultivation. The MCCs tested for garlic and A. formosanus Hay extracts were 1:10 dilution (from the original package of garlic essence) (10% w/v) and 4.0 mg/ml, respectively. In several experiments, the average number of cells infected with the influenza A virus was 59.7%; those of the cells simultaneously treated with sub-MCC of garlic A. formosanus Hay and amantadine solutions were 19.4%, 33.6%, and 30.6%, respectively. These results suggest that the expression of influenza viral antigens in cells was partially inhibited by the component in these herb extracts. In addition, the replication of viral RNA was measured by polymerase chain reaction (PCR) after the HA1 region of viral hemagglutinin gene was converted into cDNA with reverse transcription. It was shown that viral HA gene could be detected 12 hours post-inoculation even in the presence of Chinese herbs. This method could be applied to detect the replication of viral RNA when the virus-infected cells were treated with the extracts of Chinese herbs.

Induced of Systemic Resistance in Tomato Plant Against Tomato Bushy Stunt Virus by Bion and Riboflavin

The aim of this study was to evaluate the efficiency of abiotic agents Bion and Riboflavin in inducing resistance in tomato plant Geesy cultivar against Tomato bushy stunt virus (TBSV), under plastic house conditions. The experiment was included two application with induce resistance agents: Bion & Riboflavin used by two concentration for foliar spray before and after 3,6 and 2,4 days artificial inoculation with virus. The treatment was evaluated by using several parameters such as estimation of percentage and severity of disease infection, serological evaluation by DAS-ELISA, estimation of peroxidase absorbance change and some of the plant growth parameters. The best treatment was foliar spray with Bion 1 mg/ml before 6 days of virus inoculation showed reduction in the percentage of disease infection which was 37.1% compare with control treatment, on the other hand above treatment was caused high inhibition activity of virus (TBSV) multiplication which was 70% as demonstrated by ELISA absorbance values 0.296 nm compare with control treatment which inoculated with virus only was 0.972 nm. Results also indicated that the treatment by spray Riboflavin concentration 10 mM before (4 days) the inoculation of virus was inhibition of percentage of disease was 35%. On the other hand the treatment was used of Riboflavin 10 mM spray gave significant increase in the activity of peroxidase after 14 days of virus inoculation which was give 71.172 absorbance compare with control treatment which was 28.193.).

Induce resistance in tomato plants against Tomato Mosaic Virus (ToMV) by Pseudomonas fluorescens

s fluorescens This study was conducted to evaluate the ability of Pseudomona to induce systemic resistance in tomato plants against Tomato mosaic virus (ToMV) infection.Tomato seeds were surface sterilized by sodium hypochlorite (1%).Twenty seeds were soaked in Pseudomonas fluorescens suspension at 5 × 109 CFU/ml for 24 hrs anthor 20 seeds were soaked in( KB)broth for 24 hrs.The treated seeds were sown in plastic pots with 15× 10cm dimension (sterilized with ethanol )containing steril mix soil (2seeds /pot).Also non treated seeds were sown in the same soil for foliage spraying with bacterial suspension. The pots were maintained in muslin protected cages under green house condition.The plants were ToMV- inoculated at 2 primary leaves. The virus multiplication was followed by formation of local lesions on Nicotiana glutinosa .Reuslts showed that treated seeds with bacterial suspension at 5× 109 CFU/ml inhibited ToMVmultiplication by 90.30 %after 15 day of virus inoculation,2 spots were appeared on half leaf Nicotiana glutinosa inoculated by extract from treated plants compared with 26 spots on the half leaf inoculated by extract from infected plants.Similar results were obtained when the plants foliage was sprayed by the bacterial suspension (88.8%inhibition)at 5× 108CFU/ml.

Protection of melon plants against Cucumber mosaic virus infection using Pseudomonas fluorescens biofertilizer

This study was carried out to characterize a virus causing severe mosaic, yellowing, stunting and leaf deformation on melon ( Cucumis melo L.), and evaluate the capacity of Pseudomonas fluorescens as biofertilizer to improve plant growth and restrict the accumulation of the virus in the plant. The virus was identified as an isolate of Cucumber mosaic virus (CMV) by means of symptoms on indicator plants, serological characteristics using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) and immunochromatography, and molecular weight of coat protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The source of the virus infection was also determined by the same means. P. fluorescens was used as seed treatment and soil applications. The seedling grown from bacterial treated seeds in non-treated soil and those grown from non-treated seeds in bacterial treated soil were mechanically inoculated with CMV extract at the primary leaf stage. Two proteins representing CMV coat protein appeared on 10% SDS-PAGE of 24 and 26 kD. It has been found that 9 of 35 weed plants harbor CMV. Treatment seeds and soil with P. fluorescens suspension induced significant reduction in virus accumulation in the plants as proved by absorbance values of ELISA- reactions. Minimum absorbance values of ELISA reactions at 405 nm were found to be 0.160 and 0.298 for seed and soil treatments, respectively when compared with 1.190 for samples from CMV-inoculated plants (control). The inhibition activity of P. fluorescens against CMV continued to be significant up to 20 days of virus inoculation with absorbance values of ELISA-reactions (0.460 and 0.930) for seed and soil treatment, respectively. The results indicate that P. fluorescens is able to induce systemic resistance against CMV in the plants. Key words : Cucumber mosaic virus (CMV), Cucumis melo , melon, plant growth promoting microorganisms (PGPM), Pseudomonas fluorescens , viral diseases management.

The heart-protective mechanism of Qishaowuwei formula on murine viral myocarditis induced by CVB3

Aim of study The heart-protective effect and mechanism of Qishaowuwei formula (QSW), a Traditional Chinese Medicine formula composed of Radix Astragali, Radix Paeoniae Rubra and Fructus Schisandrae was investigated on murine model of viral myocarditis (VMC) induced by Coxsackievirus B3 (CVB3). Materials and methods Mice were randomly divided into infected control group, QSW high dose group, QSW medium dose group, QSW low dose group and Vitamin C plus Ribavirin treatment group. 50 mice were included in each group. The day of virus inoculation was defined as day 0 and the drug treatment continued once a day for 14 days. Mice were sacrificed on days 3, 7, 14, 21 postinoculation (p.i.). The histopathological changes of myocardium, CVB3 RNA copies in the myocardium, cardiomycytic apoptosis, the serum level of superoxide dismutase (SOD) and maleic dialdehyde (MDA) and the phenotype of T lymphocytes subsets in peripheral blood was analyzed. Results QSW treatment significantly increase the survival rate ( p < 0.05) in VMC model. Histopathology and flow cytometry inspection revealed low ratio of cardiomyocytes necrosis and apoptosis in QSW treated mice with dose dependent manner. The cardiomyocytic ultra-structure observed by transmission electron microscope also supported the above results. The ameliorated tissue damage was consistent with reduced CVB3 copy numbers detected by real-time PCR in the myocardium of QSW treated mice. The antioxidant effect of QSW was proved by elevated activity of SOD and reduced level of MDA in the serum. Furthermore, the disturbed balance of CD4+ and CD8+ subsets in peripheral blood was restored. Conclusion These results demonstrated QSW had potent protective effect against CVB3-induced heart injury and this effect might be mediated by its inhibition on viral replication, antioxidant activity and immunoregulation mechanism.

Effect of Azone upon the in vivo antiviral efficacy of cidofovir or acyclovir topical formulations in treatment/prevention of cutaneous HSV-1 infections and its correlation with skin target site free drug concentration in hairless mice

The purpose of this study is to examine the influence of Azone upon the skin target site free drug concentration ( C ∗) and its correlation with the in vivo antiviral efficacies of cidofovir (HPMPC) and acyclovir (ACV) against HSV-1 infections. Formulations of HPMPC and ACV with or without Azone were used. The in vitro skin flux experiments were performed and the C ∗ values were calculated. For the in vivo efficacy studies, hairless mice cutaneously infected with HSV-1 were used and three different treatment protocols were carried out. The protocols were chosen based upon when therapy is initiated and terminated in such a way to assess the efficacy of the test drug to cure and/or prevent HSV-1 infections. A finite dose of the formulation was topically applied twice a day for the predetermined time course for each protocol and the lesions were scored on the fifth day. For ACV formulation with Azone, the C ∗ values and hence the in vivo efficacy were much higher than those for that without Azone. In protocol #1, however, early treatment did not increase the in vivo efficacy of ACV when compared with the standard treatment protocol #3. In protocol #2 where the treatment was terminated on the day of virus inoculation, the efficacies for both ACV formulations were completely absent. Although the estimated C ∗ values for HPMPC formulations with and without Azone were comparable, formulation with Azone was much more effective than that without Azone in all treatment protocols. HPMPC formulations with Azone at similar flux values were much more effective in “treating and preventing” HSV-1 infections than those without Azone. For ACV formulations, in contrast, addition of Azone has failed to show any effect on the preventive in vivo antiviral efficacy and the enhancement of ACV in vivo antiviral efficacy was merely the skin permeation enhancement effect of Azone.

The inhibitory effect of the imidazoquinolinamine S-28828 on the pathogenesis of a type II adenovirus in turkeys

In this study we show that a type I-IFN inducing compound, S-28828, modulated the pathogenesis of an avian type II adenovirus in turkeys. By itself, S-28828 induced a strong reaction in the spleen characterized by hyperplasia of the red and white pulps as well as an increase in lymphoid cell aggregations. Oral administration of S-28828 before the time of virus inoculation suppressed significantly ( P<0.05) the replication of hemorrhagic enteritis virus (HEV) in turkeys. Two doses of 5 or 50 mg of S-28828 administered at 2 days before and at the day of virus inoculation inhibited HEV-induced pathological and histopathological lesions. Virus-induced apoptosis and reduced IgM-surface expression of B cells were suppressed by low dose S-28828 treatment. These results are of interest because mammalian adenoviruses were shown to be resistant to antiviral effects of type I IFN, the major effector cytokine induced by S-28828.

Influence of the treatment protocol upon the in vivo efficacy of cidofovir (HPMPC) and of acyclovir (ACV) formulations in topical treatment of cutaneous HSV‐1 infection in hairless mice

In recent studies we found that the topical effectiveness of acyclovir (ACV) formulations was a single‐valued function of C*— the target site free drug concentration. The topical efficacy was the same when the therapy was initiated 0, 1, or 2 days after intracutaneous herpes simplex virus type‐1 (HSV‐1) inoculation in hairless mice. The purpose of the present study was to examine the hypothesis that the topical effectiveness of cidofovir (HPMPC) would not be a single valued function of C* and that it would be dependent upon when the therapy was initiated relative to the time of viral infection. Formulations of HPMPC and ACV in 95% DMSO as a vehicle were used. Hairless mice intracutaneously infected with HSV‐1 were used, and 20 µL of the test formulation was topically applied twice a day. In protocol A, the treatment was continued until the fourth day after virus inoculation, whereas in protocol B the treatment was terminated on the day of virus inoculation. Treatment was initiated on various days ranging from day −6 to day 4, and the lesions were scored on day 5. Treatment of ACV according to protocol A proved efficacious whether started as early as 6 days before virus inoculation or later, whereas the efficacy of ACV was annihilated if applied following protocol B. For HPMPC, on the other hand, the in vivo efficacies were found to be strongly dependent on how early the therapy was initiated, and significant efficacy was observed even when the treatment was terminated on the day of virus inoculation. This difference was attributed to the virus‐independent intracellular phos‐phorylation of HPMPC and slow clearance of its metabolites from the cell. It was also noted that, similar to ACV, for HPMPC the topical efficacy is likely to be a function of C* for a fixed protocol. However, unlike for ACV, for HPMPC the efficacy was not a single‐valued function of C*.

Pimobendan inhibits the production of proinflammatory cytokines and gene expression of inducible nitric oxide synthase in a murine model of viral myocarditis

OBJECTIVESThis study was designed to examine the effects of pimobendan in a murine model of viral myocarditis in relation to proinflammatory cytokine production and nitric oxide (NO) synthesis by inducible NO synthase (iNOS) in the heart.BACKGROUNDPimobendan has been recently confirmed to improve both acute and chronic heart failure. Since the modulation of myocardial necrosis and contractile dysfunction by various proinflammatory cytokines may be partially mediated by the production of nitric oxide, the effects of pimobendan on the production of proinflammatory cytokines and NO were investigated in an animal model of viral myocarditis involving heart failure.METHODSDBA/2 mice were inoculated with the encephalomyocarditis virus. To observe its effect on survival up to 14 days, pimobendan (0.1 mg/kg or 1 mg/kg) or vehicles were given from the day of virus inoculation (day 0) orally once daily. The effects of pimobendan on histological changes, cytokine production, NO production and iNOS gene expression in the heart were studied in mice treated either with pimobendan, 1 mg/kg or with vehicles only, and sacrificed seven days after virus inoculation.RESULTSThe survival of mice improved in a dose-dependent fashion such that a significant difference (p < 0.02) was found between the higher-dose pimobendan group (20 of 30 [66.7%]) and the control group (11 of 30 [36.7%]). Histological scores for cellular infiltration (1.1 ± 0.1 vs. 2.0 ± 0.0, p < 0.001), intracardiac tumor necrosis factor (TNF)-α (18.2 ± 1.8 vs. 35.8 ± 4.2 pg/mg heart, p < 0.001) and interleukin (IL)-1β (9.3 ± 1.2 vs. 26.6 ± 7.1 pg/mg heart, p < 0.01) were significantly lower in the mice given pimobendan versus those of the control mice. Interleukin-6 levels (7.1 ± 0.8 vs. 9.2 ± 1.9 pg/mg heart) were also lower in the mice treated with pimobendan. Furthermore, intracardiac NO production was significantly (p < 0.001) less in the pimobendan group (0.165 ± 0.004 nmol/mg heart) than in the control group (0.291 ± 0.051 nmol/mg heart), and intracardiac iNOS gene expression in the mice given pimobendan was 74% lower than it was in the control animals (p < 0.01).CONCLUSIONSThese findings suggest that the beneficial effects of pimobendan in viral myocarditis are partially mediated by the inhibition of both proinflammatory cytokine production and NO synthesis by iNOS.

Evaluation of immune globulin and recombinant interferon-alpha2b for treatment of experimental Ebola virus infections.

A passive immunization strategy for treating Ebola virus infections was evaluated using BALB/ c mice, strain 13 guinea pigs, and cynomolgus monkeys. Guinea pigs were completely protected by injection of hyperimmune equine IgG when treatment was initiated early but not after viremia had developed. In contrast, mice were incompletely protected even when treatment was initiated on day 0, the day of virus inoculation. In monkeys treated with one dose of IgG on day 0, onset of illness and viremia was delayed, but all treated animals died. A second dose of IgG on day 5 had no additional beneficial effect. Pretreatment of monkeys delayed onset of viremia and delayed death several additional days. Interferon-alpha2b (2 x 10(7) IU/kg/day) had a similar effect in monkeys, delaying viremia and death by only several days. Effective treatment of Ebola infections may require a combination of drugs that inhibit viral replication in monocyte/macrophage-like cells while reversing the pathologic effects (e.g., coagulopathy) consequent to this replication.

High doses of digitalis increase the myocardial production of proinflammatory cytokines and worsen myocardial injury in viral myocarditis: a possible mechanism of digitalis toxicity.

Results of recent studies suggest that proinflammatory cytokines cause myocardial contractile dysfunction, and that the drugs used to treat heart failure modulate the production of cytokines. This study was designed to examine the effects of digoxin in a murine model of heart failure induced by viral myocarditis. Four-week-old inbred DBA/2 mice were inoculated intraperitoneally with encephalomyocarditis virus (EMCV). Digoxin was given orally in doses of 0.1, 1 or 10 mg/kg daily from the day of virus inoculation. Interleukin (IL)-1beta, IL-6 and tumor necrosis factor (TNF)-alpha production in the heart were measured on day 5 after EMCV inoculation by enzyme-linked immunosorbent assay. The 14-day mortality tended to be increased in mice treated with 1 mg/kg, and was significantly increased in the group treated with 10 mg/kg per day. Myocardial necrosis and cellular infiltration on day 6 were significantly more severe in the high-dose digoxin group than in the control group. In the animals treated with 1 mg/kg digoxin, IL-1beta was significantly higher than in the control group. Intracardiac TNF-alpha levels were increased in a dose-dependent manner. These results suggest that digoxin worsens viral myocarditis, and that its use in high doses should be avoided in patients suffering from heart failure due to viral myocarditis.

Inhibitory effect of 9-(2-phosphonylmethoxyethyl)adenine on visna virus infection in lambs: a model for in vivo testing of candidate anti-human immunodeficiency virus drugs.

The acyclic nucleoside phosphonate analog 9-(2-phosphonylmethoxyethyl)adenine (PMEA) was recently found to be effective as an inhibitor of visna virus replication and cytopathic effect in sheep choroid plexus cultures. To study whether PMEA also affects visna virus infection in sheep, two groups of four lambs each were inoculated intracerebrally with 10(6.3) TCID50 of visna virus strain KV1772 and treated subcutaneously three times a week with PMEA at 10 and 25 mg/kg, respectively. The treatment was begun on the day of virus inoculation and continued for 6 weeks. A group of four lambs were infected in the same way but were not treated. The lambs were bled weekly or biweekly and the leukocytes were tested for virus. At 7 weeks after infection, the animals were sacrificed, and cerebrospinal fluid (CSF) and samples of tissue from various areas of the brain and from lungs, spleen, and lymph nodes were collected for isolation of virus and for histopathologic examination. The PMEA treatment had a striking effect on visna virus infection, which was similar for both doses of the drug. Thus, the frequency of virus isolations was much lower in PMEA-treated than in untreated lambs. The difference was particularly pronounced in the blood, CSF, and brain tissue. Furthermore, CSF cell counts were much lower and inflammatory lesions in the brain were much less severe in the treated lambs than in the untreated controls. The results indicate that PMEA inhibits the propagation and spread of visna virus in infected lambs and prevents brain lesions, at least during early infection. The drug caused no noticeable side effects during the 6 weeks of treatment.

Outbred mice infected by an encephalomyocarditis virus variant: a model for studying chronic viral heart disease.

Male 8 to 20-week-old NMRI mice (an outbred strain) infected with the encephalomyocarditis virus (EMCV) plaque variant (PV) 7 consistently develop a distinct myocarditis with a relatively low mortality (21%). Myocarditis occurs in essence independent of the virus dose applied, and other internal organs are not affected. Nevertheless, 3.5-week-old NMRI mice perished within 5 days of virus inoculation and exhibited disseminated myofibrillar degeneration (MFD); this obviously virus-induced myocardial damage was accompanied by scanty inflammatory infiltrates. EMCV PV7 infection of adult male C57Bl/6 and DBA/2 mice causes myocarditis comparable to that seen in NMRI mice. In DBA/2 mice, however, the virus-induced myocardial necrosis is complicated by subtotal calcification. This strain has a genetically determined "spontaneous" calcification of the myocardium, as shown by the study of uninfected controls. EMCV PV7-infected NMRI mice appear a promising model for study of long-term effects of viral myocarditis, possibly including cardiomyopathy. Furthermore, this outbred mouse strain offers the possibility of examining the pathogenesis of direct viral cytolysis and its relation to MFD as well as immunologically mediated cell damage.

Attenuation phenotype of a cell culture-adapted variant of hepatitis A virus (HM175/p16) in susceptible New World owl monkeys.

The virulence of a clonally isolated, cell culture-adapted hepatitis A virus (HM175/p16) was assessed in 4 seronegative owl monkeys inoculated intravenously with 2.8 x 10(4) radioimmunofocus-forming units of virus. The virus was highly attenuated, even though its complete nucleotide sequence contains only 19 mutations from the wild-type genome. Only 3 monkeys developed antibodies to hepatitis A virus (only 2 within 96 days of virus inoculation). One monkey had viremia and significantly elevated serum aminotransferase levels. In this animal, maximum viremia and fecal shedding of virus occurred 30-33 days after inoculation. In contrast, in earlier studies of a related cell culture-adapted but still hepatovirulent virus (HM175/S18), viremia was documented in 6 of 6 animals and peak viremia and fecal shedding of virus occurred 18 or 19 days after intravenous inoculation of about one-tenth as much virus.

Dose response and timing effects in the therapy of the LP-BM5 murine retrovirus-induced lymphoproliferative immunodeficiency disease with diethyldithiocarbamate

Diethyldithiocarbamate (DTC) was used to treat the murine, retrovirus-induced, immunodeficiency disease (MAIDS). Once-weekly treatment was not effective and 800 mg/kg was toxic. When 200, 400 and 600 mg/kg were given i.p., 5 days per week, starting either on the day of virus inoculation or 14 days later, a dose- response and time- response relationship was noted. Higher doses and a 2-week delayed onset of treatment were generally more effective in reducing the development of lymphadenopathy, hypergammaglobulinemia and in prolonging survival than treatment started on the day of virus inoculation. When treatment was delayed until 10 weeks after virus inoculation existing lymphadenopathy was abrogated (treated node area 0 mm 2 compared to control 175 mm 2, P<0.0001) and survival was improved (treated 100% compared to control 12.5%, P<0.0001). However, when therapy was stopped animals died at the same rate as the untreated controls. These data indicate that DTC is active in MAIDS in a dose-responsive and time-dependent manner.

Effective therapy of the LP-BM5 murine retrovirus-induced lymphoproliferative immunodeficiency disease with diethyldithiocarbamate.

The effects of therapy with the immunomodulator diethyldithiocarbamate (DTC) on the manifestation and natural history of LP-BM5 murine retrovirus infection in adult C57 Black 6 mice was investigated. DTC itself, had limited effects on the spleen weight, serum IgM, or mitogen responses of the non-virus-infected control mice when evaluated over a 9-week period. The virus inoculum administered was such that there was approximately a twofold increase in serum IgM and a halving of phytohemagglutinin (PHA) and lipopolysaccharide (LPS) responses in about two weeks and death of all animals by about 26 weeks postinfection. Doses of DTC of 20 and 200 mg/kg weekly or 5 days per week (intraperitoneally) in mice with LP-BM5 infection did not alter the manifestations or course of the disease. Doses of 400 or 600 mg/kg given 5 days per week, starting either 2 weeks before or the day of virus inoculation significantly reduced hypergammaglobulinemia, spleen weight, lymphadenopathy, and also prolonged survival. A dose of 400 mg/kg started 2 weeks after virus inoculation resulted in partial prevention of hypergammaglobulinemia, splenomegaly, and lymphadenopathy as well as 100% survival compared with 12.5% in non-drug-treated controls at 23 weeks after virus inoculation. The 9 surviving animals in the treated group were then allocated to continue treatment or stop treatment. In the animals without further treatment, lymphadenopathy and mortality occurred starting within 6 weeks after cessation of therapy while the animals with continued treatment remained in good condition for 40 weeks. There was only a very limited and transient effect of DTC therapy on the decline of the proliferative responses to phytohemagglutinin or lipopolysaccharide in any of the treated groups in the above described experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of Rift Valley Fever in Rhesus Monkeys with Interferon-α

Prophylactic and therapeutic efficacy of recombinant leukocyte A interferon (rIFN-alpha A) and Sendai virus-induced human leukocyte interferon (HuIFN-alpha) administered intramuscularly to Rift Valley fever virus (RVFV)-infected rhesus monkeys was studied. Clinical, virologic, immunologic, and hemostatic parameters were monitored. Five daily inoculations of 5 X 10(5) units of either interferon product per kilogram of body weight, initiated 24 hours before or 6 hours after RVFV infection, prevented or greatly suppressed viremia. No clinical signs of disease or laboratory evidence of impaired hemostasis was observed. Serum neutralizing antibody to RVFV was detected within 6 days of virus inoculation. Prophylactic administration of 5 X 10(4) or 5 X 10(3) units of rIFN-alpha A per kilogram also limited viremia, hepatocellular damage, and hemostatic derangement. Untreated, RVFV-infected, control monkeys developed high-titered viremia, clinical disease, and impaired hemostasis. These data suggest that rIFN-alpha A and HuIFN-alpha are effective in protecting RVFV-infected rhesus monkeys from viremia and hepatocellular damage and may be beneficial in human RVF infection.