title: In vitro and in vivo efficacy of fluorodeoxycytidine analogs against highly pathogenic avian influenza H5N1, seasonal, and pandemic H1N1 virus infections.
abstract: Various fluorodeoxyribonucleosides were evaluated for their antiviral activities against influenza virus infections in vitro and in vivo. Among the most potent inhibitors was 2'-deoxy-2'-fluorocytidine (2'-FdC). It inhibited various strains of low and highly pathogenic avian influenza H5N1 viruses, pandemic H1N1 viruses, an oseltamivir-resistant pandemic H1N1 virus, and seasonal influenza viruses (H3N2, H1N1, influenza B) in MDCK cells, with the 90% inhibitory concentrations ranging from 0.13 to 4.6 μM, as determined by a virus yield reduction assay. 2'-FdC was then tested for efficacy in BALB/c mice infected with a lethal dose of highly pathogenic influenza A/Vietnam/1203/2004 H5N1 virus. 2'FdC (60 mg/kg/d) administered intraperitoneally (i.p.) twice a day beginning 24 h after virus exposure significantly promoted survival (80% survival) of infected mice (p=0.0001). Equally efficacious were the treatment regimens in which mice were treated with 2'-FdC at 30 or 60 mg/kg/day (bid X 8) beginning 24 h before virus exposure. At these doses, 70-80% of the mice were protected from death due to virus infection (p=0.0005, p=0.0001; respectively). The lungs harvested from treated mice at day four of the infection displayed little surface pathology or histopathology, lung weights were lower, and the 60 mg/kg dose reduced lung virus titers, although not significantly compared to the placebo controls. All doses were well tolerated in uninfected mice. 2'-FdC could also be administered as late as 72 h post virus exposure and still significantly protect 60% mice from the lethal effects of the H5N1 virus infection (p=0.019). Other fluorodeoxyribonucleosides tested in the H5N1 mouse model, 2'-deoxy-5-fluorocytidine and 2'-deoxy-2',2'-difluorocytidine, were very toxic at higher doses and not inhibitory at lower doses. Finally, 2'-FdC, which was active in the H5N1 mouse model, was also active in a pandemic H1N1 influenza A infection model in mice. When given at 30 mg/kg/d (bid X 5) beginning 24h before virus exposure), 2'-FdC also significantly enhanced survival of H1N1-infected mice (50%, p=0.038) similar to the results obtained in the H5N1 infection model using a similar dosing regimen (50%, p<0.05). Given the demonstrated in vitro and in vivo inhibition of avian influenza virus replication, 2'FdC may qualify as a lead compound for the development of agents treating influenza virus infections.
authors.affiliation: Institute for Antiviral Research, Department of Animal, Dairy and Veterinary Science, 5600 Old Main Hill, Logan, Utah State University, Logan, UT 84322, USA.
authors.forename: Yohichi
authors.initials: Y
authors.lastname: Kumaki
authors.forename: Craig W
authors.initials: CW
authors.lastname: Day
authors.forename: Donald F
authors.initials: DF
authors.lastname: Smee
authors.forename: John D
authors.initials: JD
authors.lastname: Morrey
authors.forename: Dale L
authors.initials: DL
authors.lastname: Barnard
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000008:administration & dosage* / Q000494:pharmacology; D002460:Cell Line; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D004285:Dogs; D005260:Female; D006651:Histocytochemistry; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects*; D053122:Influenza A Virus, H3N2 Subtype / Q000187:drug effects*; D053124:Influenza A Virus, H5N1 Subtype / Q000187:drug effects*; D007274:Injections, Intraperitoneal; D008168:Lung / Q000473:pathology / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D009976:Orthomyxoviridae Infections / Q000188:drug therapy* / Q000517:prevention & control* / Q000821:virology; D016019:Survival Analysis; D019562:Viral Load
chemical_list: D000998:Antiviral Agents; D003841:Deoxycytidine; C007251:2'-fluoro-2'-deoxycytidine