title: Mutations at the monomer-monomer interface away from the active site of influenza B virus neuraminidase reduces susceptibility to neuraminidase inhibitor drugs.
abstract: Amino acid changes in or near the active site of neuraminidase (NA) in influenza viruses reduce the susceptibility to NA inhibitor drugs. Here, we report the recovery of three influenza B viruses with reduced susceptibilities to NA inhibitors from human patients with no history of antiviral drug treatment. The three viruses were isolated by inoculating Madin-Darby canine kidney (MDCK) cells with respiratory specimens from the patients. NA inhibition assays demonstrated that two of the three isolates showed a highly reduced susceptibility to peramivir and moderately reduced susceptibility to oseltamivir, zanamivir, and laninamivir. The remaining one isolate exhibited moderately reduced sensitivity to peramivir, zanamivir, and laninamivir but was susceptible to oseltamivir. A sequence analysis of viruses propagated in MDCK cells revealed that all three isolates contained a single mutation (Q138R, P139S, or G140R) in NA not previously associated with reduced susceptibility to NA inhibitors. However, pyrosequencing analyses showed that the Q138R and G140R mutations were below a detectable level in the original clinical specimens; the P139S mutation was detected at a very low level, suggesting that the mutant viruses may be preferably selected during propagation in MDCK cells. The NA crystallographic structure showed that these mutations were located at the interface between the two monomers of the NA tetramer, away from the NA active site. In addition to amino acid substitutions around the active site of NA, these observations suggest that alterations in the monomer-monomer interface region of NA may contribute to reduced sensitivity to NA inhibitors.
authors.affiliation: Laboratory of Influenza Virus Surveillance, Influenza Virus Research Center, National Institute of Infectious Diseases, Tokyo, 208-0011, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Fujisaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Imai
authors.forename: Emi
authors.initials: E
authors.lastname: Takashita
authors.forename: Tae
authors.initials: T
authors.lastname: Taniwaki
authors.forename: Hong
authors.initials: H
authors.lastname: Xu
authors.forename: Noriko
authors.initials: N
authors.lastname: Kishida
authors.forename: Masaru
authors.initials: M
authors.lastname: Yokoyama
authors.forename: Hironori
authors.initials: H
authors.lastname: Sato
authors.forename: Masato
authors.initials: M
authors.lastname: Tashiro
authors.forename: Takato
authors.initials: T
authors.lastname: Odagiri
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D020134:Catalytic Domain; D004285:Dogs; D024882:Drug Resistance, Viral / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006146:Guanidines; D006801:Humans; D009981:Influenza B virus / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D007251:Influenza, Human / Q000821:virology*; D007564:Japan; D061985:Madin Darby Canine Kidney Cells; D008958:Models, Molecular; D009154:Mutation; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics*; D053139:Oseltamivir / Q000494:pharmacology; D011714:Pyrans; D012794:Sialic Acids; D014764:Viral Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D053243:Zanamivir / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D006146:Guanidines; D011714:Pyrans; D012794:Sialic Acids; D014764:Viral Proteins; D053139:Oseltamivir; C546918:laninamivir; D009439:Neuraminidase; D053243:Zanamivir