title: In vitro selection and characterization of influenza A (A/N9) virus variants resistant to a novel neuraminidase inhibitor, A-315675.
abstract: With the recent introduction of neuraminidase (NA) inhibitors into clinical practice for the treatment of influenza virus infections, considerable attention has been focused on the potential for resistance development and cross-resistance between different agents from this class. A-315675 is a novel influenza virus NA inhibitor that has potent enzyme activity and is highly active in cell culture against a variety of strains of influenza A and B viruses. To further assess the therapeutic potential of this compound, in vitro resistance studies have been conducted and a comparative assessment has been made relative to oseltamivir carboxylate. The development of viral resistance to A-315675 was studied by in vitro serial passage of influenza A/N9 virus strains grown in MDCK cells in the presence of increasing concentrations of A-315675. Parallel passaging experiments were conducted with oseltamivir carboxylate, the active form of a currently marketed oral agent for the treatment of influenza virus infections. Passage experiments with A-315675 identified a variant at passage 8 that was 60-fold less susceptible to the compound. Sequencing of the viral population identified an E119D mutation in the NA gene, but no mutations were observed in the hemagglutinin (HA) gene. However, by passage 10 (2.56 microM A-315675), two mutations (R233K, S339P) in the HA gene appeared in addition to the E119D mutation in the NA gene, resulting in a 310-fold-lower susceptibility to A-315675. Further passaging at higher drug concentrations had no effect on the generation of further NA or HA mutations (20.5 microM A-315675). This P15 virus displayed 355-fold-lower susceptibility to A-315675 and >175-fold-lower susceptibility to zanamivir than did wild-type virus, but it retained a high degree of susceptibility to oseltamivir carboxylate. By comparison, virus variants recovered from passaging against oseltamivir carboxylate (passage 14) harbored an E119V mutation and displayed a 6,000-fold-lower susceptibility to oseltamivir carboxylate and a 175-fold-lower susceptibility to zanamivir than did wild-type virus. Interestingly, this mutant still retained susceptibility to A-315675 (42-fold loss). This suggests that cross-resistance between A-315675- and oseltamivir carboxylate-selected variants in vitro is minimal.
authors: Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, Illinois 60064, USA. m.molla@abbott.com
authors: Akhteruzzaman
authors: A
authors: Molla
authors: Warren
authors: W
authors: Kati
authors: Robert
authors: R
authors: Carrick
authors: Kevin
authors: K
authors: Steffy
authors: Yan
authors: Y
authors: Shi
authors: Debra
authors: D
authors: Montgomery
authors: Nanette
authors: N
authors: Gusick
authors: Vincent S
authors: VS
authors: Stoll
authors: Kent D
authors: KD
authors: Stewart
authors: Teresa I
authors: TI
authors: Ng
authors: Clarence
authors: C
authors: Maring
authors: Dale J
authors: DJ
authors: Kempf
authors: William
authors: W
authors: Kohlbrenner
mesh_terms: D000081:Acetamides / Q000494:pharmacology; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D004285:Dogs; D024882:Drug Resistance, Viral / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D014644:Genetic Variation; D006146:Guanidines; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects* / Q000235:genetics; D016296:Mutagenesis; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000235:genetics; D053139:Oseltamivir; D010641:Phenotype; D011714:Pyrans; D011759:Pyrrolidines / Q000494:pharmacology*; D012794:Sialic Acids / Q000494:pharmacology; D053243:Zanamivir
chemical_list: C456059:A 315675; D000081:Acetamides; D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D006146:Guanidines; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011714:Pyrans; D011759:Pyrrolidines; D012794:Sialic Acids; D053139:Oseltamivir; D009439:Neuraminidase; D053243:Zanamivir