Efficacy of 1-β- d -Ribofuranosyl-1,2,4-Triazole-3-carboxamide Against Influenza Virus Infections in Mice

A novel nucleoside analog, 4(5H)-oxo-l1-,-D-ribofuranosylpyrazolo [3,4-d]pyrimidine-3-thiocarboxamide (N10169), was evaluated in cell culture and in animals for antiviral activity against DNA and RNA viruses. The compound was highly active against strains of adeno-, vaccinia, influenza B, paramyxo-, picorna-, and reoviruses, with 50% inhibition of virus-induced cytopathology at 1 to 10 ,uM. Lesser or no antiviral effects were observed against herpes simplex, cytomegalo-, corona-, influenza A, vesicular stomatitis, and visna viruses. Drug potency against certain viruses was highly cell line dependent (N10169 was highly active in HeLa cells but was much less potent in Vero cells). This was correlated, in part, to differences in levels of adenosine kinase activity in these cell lines, since adenosine kinase appears to phosphorylate N10169 to its active form.N10169 was inhibitory to proliferating cells at antiviral concentrations, whereas stationary-phase monolayers tolerated higher concentrations (5100 ,uM). Exogenous uridine was able to reverse the virus-inhibitory effects of the compound, leading to the discovery that N10169 5'-monophosphate is a potent inhibitor of cellular orotidylate decarboxylase. N10169 was evaluated in mice that were infected intraperitoneally with banzi virus or inoculated intranasally with influenza B virus, and in hamsters that were infected intranasally with vaccinia virus. In each model, intraperitoneal injection of N10169 (100 to 300 mg/kg per day for 7 days) twice daily was ineffective, whereas intraperitoneal injection of ribavirin showed some benefit in the influenza B and banzi virus infection models.In a recent report (3) a series of pyrazolo [3,4-d]pyrimidine nucleoside analogs possessing antiviral and antitumor properties was described. Additional studies of these compounds were undertaken to determine the spectrum of viruses which would be inhibited and to ascertain any therapeutic potential in animals. One compound, 4(5H)-oxo-1-P-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-3-thiocarboxamide (N10169; Fig. 1), although similar in structure to the broad-spectrum antiviral agent ribavirin (18), was found to have an unusual spectrum of antiviral activity, degree of potency, and mode of action. Although the compound is related to purine nucleosides, it was found to be a potent inhibitor of pyrimidine biosynthesis. As the work proceeded it was determined that the properties of N10169 were remarkably similar to those of 6-azauridine (23). The compounds related to N10169 (3) did not exhibit the same degree of potency and spectrum of activity that N10169 did in vitro. In this report we summarize the results of cell culture studies and evaluate the antiviral activity of this novel compound in appropriate animal infection models.

Section: Materials Ani) Methodsmentioning

confidence: 99%

Novel pyrazolo[3,4-d]pyrimidine nucleoside analog with broad-spectrum antiviral activity

Smee¹,

McKernan²,

Nord³

et al. 1987

“…It has been suggested that this inhibition would be lethal to replicating virus but would have little effect on resting cells. Some evidence for this is provided by cytotoxicity studies on uninfected cells, wherein it has been reported that even at high concentrations (1,000 ,ug/ml), little visible cytotoxicity in terms of degenerating cells or destruction of cell monolayers was seen, although the rate of cell proliferation was effectively reduced (2,6).…”

mentioning

confidence: 99%

“…Ribavirin (1-fl-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a synthetic nucleoside which has both in vitro (2,6,10) and in vivo (1,3,5,7) antiviral activity against a variety of ribonucleic acid and deoxyribonucleic acid viruses. The compound acts by interfering with guanidine monophosphate formation and subsequent nucleic acid synthesis (9).…”

mentioning

confidence: 99%

Effects of Ribavirin on BHK-21 Cells Acutely or Persistently Infected With Mumps Virus

McCammon

Riesser

1979

The effects of ribavirin on BHK-21 cells acutely infected with mumps virus were compared to the effects of the drug on the same cell line persistently infected with mumps virus. Visible cytotoxicity was minimal for both cell types; however, there was an inhibition of cell replication with increasing drug concentrations. Ribavirin had marked antiviral activity against both the acute and persistent infections as determined by an inhibition of hemadsorption plaque formation, decreased immunofluorescence, and a reduction in the release of infectious virus. Even after the drug had been on the persistently infected cells for 72 h, there was still antigen production detectable by immunofluorescence, although the cells no longer hemadsorbed chicken erythrocytes. Ribavirin removal from both types of infection resulted in the renewed synthesis of virus.

“…Recently, ribavirin (1-3-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was found to be effective for the treatment of type A influenza virus infections in mice (1,(3)(4)(5). These experiments indicated that small-particle aerosols (mass median diameter, 1.4 gm) of ribavirin were more effective in reducing mortality, lesions in the lung, and virus concentrations in the lungs than approximately equivalent doses of drug given intraperitoneally (i.p.)…”

mentioning

confidence: 99%

“…A virus control group received no treatment. The degree of gross pathology in the lungs (lung lesion score) was evaluated in three mice on day 4 and in five mice on day 7 by 1 Present address: Plum Island Animal Disease Center, P.O. Box 848, Greenport, NY 11944. methods that have been described previously (4).…”

mentioning

confidence: 99%

Response of Influenza Virus-Infected Mice to Selected Doses of Ribavirin Administered Intraperitoneally or by Aerosol

Berendt

Walker

Dominik

et al. 1977

The effects of graded doses of ribavirin administered either by aerosol or intraperitoneally were compared in influenza virus-infected mice. The median effective dose values (based upon percent survival) were 3.3 and 15.8 mg/kg per day for the aerosol and intraperitoneal routes, respectively. Lung lesion scores and titer of virus were lower after aerosol than intraperitoneal therapy.Recently, ribavirin (1-3-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was found to be effective for the treatment of type A influenza virus infections in mice (1, 3-5). These experiments indicated that small-particle aerosols (mass median diameter, 1.4 gm) of ribavirin were more effective in reducing mortality, lesions in the lung, and virus concentrations in the lungs than approximately equivalent doses of drug given intraperitoneally (i.p.) (4). However, the data did not indicate how much better aerosol administration was than i.p. in terms of dosage required to achieve the same effect, i.e., how much ribavirin was required to achieve an effective dose that would allow >50% of the mice to survive (ED50). This information would be helpful when considering the possible administration of ribavirin by aerosol for the treatment of humans, especially if a significant therapeutic advantage was gained by using the aerosol route.The objective of this research was to determine the response of influenza virus-infected mice to selected doses of ribavirin given either by aerosol or i.p.The procedures employed for housing, infecting, and treating mice [Tac:(SW)fBR] have been described by Stephen et al. (4). Four selected doses of ribavirin were administered by each route. Doses ranged from 2.5 to 20 mg/kg per day by aerosol and from 5.0 to 40.0 mg/kg per day by the i.p. route. Treatment was initiated at 6 h after exposure to the virus and was repeated daily for a total of 5 days. i.p. injections were given once daily at the same time as the aerosols. A virus control group received no treatment. The degree of gross pathology in the lungs (lung lesion score) was evaluated in three mice on day 4 and in five mice on day 7 by 1 Present address: Plum Island Animal Disease Center, P.O. Box 848, Greenport, NY 11944. methods that have been described previously (4). The concentration of virus in the lungs was also determined on day 4 by previously described methods (5). Survival was recorded daily for 21 days in 25 mice that were randomly allocated for this purpose from each treatment group. Survival data from five replicate experiments were analyzed by probit analysis (2), and the dose of ribavirin yielding 50% survival (ED50) was calculated together with 95% confidence limits. Lung lesion scores and lung virus concentration data were evaluated by analysis of variance.The results are shown graphically in Fig. 1. The ED50 values after aerosol and i.p. administration of ribavirin were 3.3 mg/kg per day (95% confidence limits, 2.5 to 4.3) and 15.8 mg/ kg per day (95% confidence limits, 12.7 and 19.5), respectively. The slopes (data not shown) for the regre...