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Volume 25, Number 4—April 2019
Research Letter

Reduced Susceptibility to Neuraminidase Inhibitors in Influenza B Isolate, Canada

Yacine Abed1, Clément Fage1, Patrick Lagüe, Julie Carbonneau, Jesse Papenburg, Donald C. Vinh, and Guy BoivinComments to Author 
Author affiliations: Laval University, Québec City, Québec, Canada (Y. Abed, C. Fage, P. Lagüe, J. Carbonneau, G. Boivin); Montreal Children’s Hospital, Montreal, Québec (J. Papenburg); McGill University Health Center, Montreal (D.C. Vinh)

Main Article


Susceptibility profiles and NA activity of influenza B virus isolates and susceptibility profiles of recombinant influenza B NAs determined by assays using the fluorescent MUNANA substrate, Canada*

Sample type
IC50 in nM + SD (fold increase) [phenotype]†
NA activity, Vmax
Clinical isolate
B/Phuket/3073/2013, vaccine 18.98 + 3.89 0.70 + 0.17 0.74 + 0.02 ND
B/Québec/88855/2018, WT 17.47 ± 1.43 (1) [NI] 0.85 ± 0.09 (1) [NI] 0.92 ± 0.09 (1) [NI] 2.24 ± 0.3
B/Québec/1182C/2018, Gly407Ser
104 + 14.62 (5.97) [RI]
27.58 + 2.56 (32.44) [RI]
26.08 + 0.1 (38.34) [RI]
2.18 + 0.47
Recombinant neuraminidase
B/Quebec/88855/2018, WT 11.16 + 5.25 (1) [NI] 0.97 + 0.27 (1) [NI] 0.76 + 0.19 (1) [NI] ND
B/Quebec/88855/2018, Gly407Ser 46.52 + 12.58 (4.16) [NI] 9.77 + 0.90 (10.07) [RI] 12.44 + 5.47 (16.36) [RI] ND

*Values are from a representative experiment performed in duplicate. IC50, 50% inhibitory concentration; MUNANA, 2 '-(4-methylumbelliferyl)-α-D-N-acteylneuraminic acid; NA, neuraminidase; NAI, neuraminidase inhibitor; ND, not done; NI, normal inhibition (<5-fold increase in IC50 over WT); RI, reduced inhibition (5- to 50-fold increase in IC50 over WT); Vmax, maximum velocity of substrate conversion; WT, wild type.
†The phenotype of susceptibility to NAI following the World Health Organization guidelines.
‡Numbers indicate mean Vmax values (U/sec) ± SD of a kinetics experiment performed in triplicate.

Main Article

1These authors contributed equally to this article.

Page created: March 18, 2019
Page updated: March 18, 2019
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