title: A conformational restriction in the influenza A virus neuraminidase binding site by R152 results in a combinational effect of I222T and H274Y on oseltamivir resistance.
abstract: The I222K, I222R, and I222T substitutions in neuraminidase (NA) have been found in clinically derived 2009 pandemic influenza A/H1N1 viruses with altered susceptibilities to NA inhibitors (NAIs). The effects of these substitutions, together with the most frequently observed resistance-related substitution, H274Y, on viral fitness and resistance mechanisms were further investigated in this study. Reduced sensitivities to oseltamivir were observed in all three mutants (I222K, I222R, and I222T). Furthermore, the I222K and I222T substitutions had a combinational effect of further increasing resistance in the presence of H274Y, which might result from a conformational restriction in the NA binding site. Of note, by using molecular dynamics simulations, R152, the neighbor of T222, was observed to translate to a position closer to T222, resulting in the narrowing of the binding pocket, which otherwise only subtends the residue substitution of H274Y. Moreover, significantly attenuated NA function and viral growth abilities were found in the I222K+H274Y double mutant, while the I222T+H274Y double mutant exhibited slightly delayed growth but had a peak viral titer similar to that of the wild-type virus in MDCK cells. The relative growth advantage of the I222T mutant versus the I222K mutant and the higher frequency of I222T emerging in N1 subtype influenza viruses raise concerns necessitating close monitoring of the dual substitutions I222T and H274Y.
authors.affiliation: Chinese National Influenza Center, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, People's Republic of China.
authors.forename: Lan
authors.initials: L
authors.lastname: Huang
authors.forename: Yang
authors.initials: Y
authors.lastname: Cao
authors.forename: Jianfang
authors.initials: J
authors.lastname: Zhou
authors.forename: Kun
authors.initials: K
authors.lastname: Qin
authors.forename: Wenfei
authors.initials: W
authors.lastname: Zhu
authors.forename: Yun
authors.initials: Y
authors.lastname: Zhu
authors.forename: Lei
authors.initials: L
authors.lastname: Yang
authors.forename: Dayan
authors.initials: D
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Wei
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Shu
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D001665:Binding Sites / Q000235:genetics; D004285:Dogs; D024882:Drug Resistance, Viral / Q000235:genetics; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects / Q000235:genetics; D009980:Influenza A virus / Q000187:drug effects* / Q000235:genetics; D007668:Kidney / Q000166:cytology / Q000821:virology; D061985:Madin Darby Canine Kidney Cells / Q000821:virology; D009439:Neuraminidase / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D053139:Oseltamivir / Q000494:pharmacology*; D011487:Protein Conformation; D014779:Virus Replication / Q000235:genetics
chemical_list: D000998:Antiviral Agents; D053139:Oseltamivir; D009439:Neuraminidase