Impact of mutations at residue I223 of the neuraminidase protein on the resistance profile, replication level, and virulence of the 2009 pandemic influenza virus.
Amino acid substitutions at residue I223 of the neuraminidase (NA) protein have been identified in 2009 pandemic influenza (pH1N1) variants with altered susceptibilities to NA inhibitors (NAIs). We used reverse genetics and site-directed mutagenesis to generate the recombinant A/Québec/144147/09 pH1N1 wild-type virus (WT) and five (I223R, I223V, H275Y, I223V-H275Y, and I223R-H275Y) NA mutants. A fluorimetry-based assay was used to determine 50% inhibitory concentrations (IC(50)s) of oseltamivir, zanamivir, and peramivir. Replicative capacity was analyzed by viral yield assays in ST6GalI-MDCK cells. Infectivity and transmission of the WT, H275Y, and I223V-H275Y recombinant viruses were evaluated in ferrets. As expected, the H275Y mutation conferred resistance to oseltamivir (982-fold) and peramivir (661-fold) compared to the drug-susceptible recombinant WT. The single I223R mutant was associated with reduced susceptibility to oseltamivir (53-fold), zanamivir (7-fold) and peramivir (10-fold), whereas the I223V virus had reduced susceptibility to oseltamivir (6-fold) only. Interestingly, enhanced levels of resistance to oseltamivir and peramivir and reduced susceptibility to zanamivir (1,647-, 17,347-, and 16-fold increases in IC(50)s, respectively) were observed for the I223R-H275Y recombinant, while the I223V-H275Y mutant exhibited 1,733-, 2,707-, and 2-fold increases in respective IC(50)s. The I223R and I223V changes were associated with equivalent or higher viral titers in vitro compared to the recombinant WT. Infectivity and transmissibility in ferrets were comparable between the recombinant WT and the H275Y or I223V-H275Y recombinants. In conclusion, amino acid changes at residue I223 may alter the NAI susceptibilities of pH1N1 variants without compromising fitness. Consequently, I223R and I223V mutations, alone or with H275Y, need to be thoroughly monitored.
Research Center in Infectious Diseases of the CHUQ-CHUL and Laval University, Québec City, Québec, Canada.
Andrés
A
Pizzorno
Yacine
Y
Abed
Xavier
X
Bouhy
Edith
E
Beaulieu
Corey
C
Mallett
Rupert
R
Russell
Guy
G
Boivin
D000146:Acids, Carbocyclic; D019943:Amino Acid Substitution; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D002460:Cell Line; D003517:Cyclopentanes / Q000494:pharmacology; D004285:Dogs; D024882:Drug Resistance, Viral / Q000235:genetics*; D005289:Ferrets; D006146:Guanidines / Q000494:pharmacology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000187:drug effects* / Q000235:genetics; D007251:Influenza, Human / Q000821:virology; D020128:Inhibitory Concentration 50; D008297:Male; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009439:Neuraminidase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009976:Orthomyxoviridae Infections / Q000635:transmission / Q000821:virology*; D053139:Oseltamivir / Q000494:pharmacology; D058873:Pandemics; D059386:Reverse Genetics; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects; D053243:Zanamivir / Q000494:pharmacology
D000146:Acids, Carbocyclic; D000998:Antiviral Agents; D003517:Cyclopentanes; D006146:Guanidines; D014764:Viral Proteins; D053139:Oseltamivir; D009439:Neuraminidase; D053243:Zanamivir; C414210:peramivir