title: T-705 (favipiravir) induces lethal mutagenesis in influenza A H1N1 viruses in vitro.
abstract: Several novel anti-influenza compounds are in various phases of clinical development. One of these, T-705 (favipiravir), has a mechanism of action that is not fully understood but is suggested to target influenza virus RNA-dependent RNA polymerase. We investigated the mechanism of T-705 activity against influenza A (H1N1) viruses by applying selective drug pressure over multiple sequential passages in MDCK cells. We found that T-705 treatment did not select specific mutations in potential target proteins, including PB1, PB2, PA, and NP. Phenotypic assays based on cell viability confirmed that no T-705-resistant variants were selected. In the presence of T-705, titers of infectious virus decreased significantly (P < 0.0001) during serial passage in MDCK cells inoculated with seasonal influenza A (H1N1) viruses at a low multiplicity of infection (MOI; 0.0001 PFU/cell) or with 2009 pandemic H1N1 viruses at a high MOI (10 PFU/cell). There was no corresponding decrease in the number of viral RNA copies; therefore, specific virus infectivity (the ratio of infectious virus yield to viral RNA copy number) was reduced. Sequence analysis showed enrichment of G→A and C→T transversion mutations, increased mutation frequency, and a shift of the nucleotide profiles of individual NP gene clones under drug selection pressure. Our results demonstrate that T-705 induces a high rate of mutation that generates a nonviable viral phenotype and that lethal mutagenesis is a key antiviral mechanism of T-705. Our findings also explain the broad spectrum of activity of T-705 against viruses of multiple families.
authors: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors: Tatiana
authors: T
authors: Baranovich
authors: Sook-San
authors: SS
authors: Wong
authors: Jianling
authors: J
authors: Armstrong
authors: Henju
authors: H
authors: Marjuki
authors: Richard J
authors: RJ
authors: Webby
authors: Robert G
authors: RG
authors: Webster
authors: Elena A
authors: EA
authors: Govorkova
mesh_terms: D000577:Amides / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D004285:Dogs; D055808:Drug Discovery / Q000379:methods; D066298:In Vitro Techniques; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics* / Q000472:pathogenicity; D061985:Madin Darby Canine Kidney Cells; D016296:Mutagenesis / Q000187:drug effects* / Q000235:genetics; D009976:Orthomyxoviridae Infections / Q000188:drug therapy*; D011719:Pyrazines / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000577:Amides; D000998:Antiviral Agents; D011719:Pyrazines; C462182:favipiravir