In vitro and in vivo activities of anti-influenza virus compound T-705

Antimicrob Agents Chemother. 2002 Apr;46(4):977-81. doi: 10.1128/aac.46.4.977-981.2002.


T-705 (6-fluoro-3-hydroxy-2-pyrazinecarboxamide) has been found to have potent and selective inhibitory activity against influenza virus. In an in vitro plaque reduction assay, T-705 showed potent inhibitory activity against influenza A, B, and C viruses, with 50% inhibitory concentrations (IC(50)s) of 0.013 to 0.48 microg/ml, while it showed no cytotoxicity at concentrations up to 1,000 microg/ml in Madin-Darby canine kidney cells. The selectivity index for influenza virus was more than 2,000. It was also active against a neuraminidase inhibitor-resistant virus and some amantadine-resistant viruses. T-705 showed weak activity against non-influenza virus RNA viruses, with the IC(50)s being higher for non-influenza virus RNA viruses than for influenza virus, and it had no activity against DNA viruses. Orally administered T-705 at 100 mg/kg of body weight/day (four times a day) for 5 days significantly reduced the mean pulmonary virus yields and the rate of mortality in mice infected with influenza virus A/PR/8/34 (3 x 10(2) PFU). These results suggest that T-705 may be a compound that is useful and highly selective against influenza virus infections and that has a mode of action different from those of commercially available drugs, such as amantadine, rimantadine, and neuraminidase inhibitors.

MeSH terms

  • Amides / pharmacology*
  • Amides / therapeutic use*
  • Animals
  • Antiviral Agents / pharmacology*
  • Antiviral Agents / therapeutic use*
  • Cell Line
  • Drug Screening Assays, Antitumor
  • Humans
  • Influenza, Human / drug therapy*
  • Influenza, Human / virology
  • Lung / virology
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Microbial Sensitivity Tests
  • Orthomyxoviridae / drug effects*
  • Pyrazines / pharmacology*
  • Pyrazines / therapeutic use*
  • Viruses / drug effects


  • Amides
  • Antiviral Agents
  • Pyrazines
  • favipiravir