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Volume 27, Number 7—July 2021

Cluster of Oseltamivir-Resistant and Hemagglutinin Antigenically Drifted Influenza A(H1N1)pdm09 Viruses, Texas, USA, January 2020

Teena Mohan1, Ha T. Nguyen1, Krista Kniss, Vasiliy P. Mishin, Angiezel A. Merced-Morales, Jennifer Laplante, Kirsten St. George, Patricia Blevins, Anton Chesnokov, Juan A. De La Cruz, Rebecca Kondor, David E. Wentworth, and Larisa V. GubarevaComments to Author 
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (T. Mohan, H.T. Nguyen, K. Kniss, V.P. Mishin, A.A. Merced-Morales, A. Chesnokov, J.A. De La Cruz, R. Kondor, D.E. Wentworth, L.V. Gubareva); General Dynamics Information Technology, Atlanta (T. Mohan, H.T. Nguyen); New York State Department of Health, Albany, New York, USA (J. Laplante, K. St. George); San Antonio Metropolitan Health District, San Antonio, Texas, USA (P. Blevins)

Main Article

Table 1

Susceptibility to NA inhibitors of influenza A(H1N1)pdm09 virus isolates from border detention center inhabitants, Texas, USA, January 2020*

Virus NA resistance marker Mean IC50 ± SD, nM (fold difference)
Zanamivir Oseltamivir Peramivir Laninamivir
A/Texas/26/2020 H275Y 0.29 + 0.01 (2) 200.99 + 21.56 (1,182) 23.34 + 6.18 (333) 0.53 + 0.04 (2)
A/Texas/136/2020 H275Y 0.32 + 0.00 (2) 247.44 + 20.52 (1,456) 25.09 + 1.08 (358) 0.59 + 0.04 (3)
A/Texas/137/2020 H275Y 0.33 + 0.04 (2) 229.50 + 35.77 (1,350) 23.32 + 0.29 (333) 0.56 + 0.03 (3)
0.31 + 0.02 (2)
228.41 + 27.05 (1,344)
24.15 + 1.10 (345)
0.51 + 0.02 (2)
A/Illinois/45/2019 Wildtype 0.19 0.17 0.07 0.22
A/Alabama/03/2020 H275Y 0.27 (1) 139.71 (822) 12.43 (178) 0.47 (2)

*The drug susceptibility of MDCK-grown viruses was determined using a NA inhibition assay. Reference viruses are from the Centers for Disease Control and Prevention Neuraminidase Inhibitor Susceptibility Reference Virus Panel version 3.0 (Atlanta, GA, USA). IC50 fold increase was determined by comparing to wild-type reference virus IC50. According to the World Health Organization Antiviral Working Group criteria, an increase below 10-fold constitutes normal inhibition, an increase of 10–100-fold is considered as reduced inhibition and an increase >100-fold is classified as highly reduced inhibition. IC50, concentration of drug needed to inhibit NA by 50%; NA, neuraminidase.

Main Article

1These authors contributed equally to this article.

Page created: May 03, 2021
Page updated: June 17, 2021
Page reviewed: June 17, 2021
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