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Volume 19, Number 12—December 2013

Research

Antiviral Susceptibility of Highly Pathogenic Avian Influenza A(H5N1) Viruses Isolated from Poultry, Vietnam, 2009–2011

Ha T. Nguyen, Tung Nguyen, Vasiliy P. Mishin, Katrina Sleeman, Amanda Balish, Joyce Jones, Adrian Creanga, Henju Marjuki, Timothy M. Uyeki, Dang H. Nguyen, Diep T. Nguyen, Hoa T. Do, Alexander I. Klimov, Charles T. Davis, and Larisa V. GubarevaComments to Author 
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (H.T. Nguyen, V.P. Mishin, K. Sleeman, A. Balish, J. Jones, H. Marjuki, T.M. Uyeki, A.I. Klimov, C.T. Davis, L.V. Gubareva); Battelle Memorial Institute, Atlanta (H.T. Nguyen, A. Creanga); National Center for Veterinary Diagnostics, Hanoi, Vietnam (T. Nguyen, D.H. Nguyen, D.T. Nguyen); Atlanta Research and Education Foundation, Atlanta (J. Jones)

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Table 2

Characterization of statistical outliers identified in neuraminidase inhibition assay*

Clade Virus name Neuraminidase gene change† IC50, nmol/L; mean±SD (fold)‡
Oseltamivir Zanamivir Peramivir Laninamivir
1.1
A/ck/VN/NCVD-780/2011 R430W 0.69 ± 0.25 (12) 18.89 ± 2.18 (73) 0.29 ± 0.03 (2) 2.62 ± 0.02 (29)
A/ck/VN/NCVD-878/2011 V149A 0.16 (3) 1.33 (5) 0.13 (1) NT
A/ck/VN/NCVD-776/2011 H253Y 0.52 ± 0.24 (9) 0.20 ± 0.03 (1) 0.10 ± 0.03 (1) 0.14 ± 0.01 (1)
Median
NA
0.06
0.26
0.13
0.09 ± 0.01§
2.3.2.1
A/dk/VN/NCVD-664/2010 H275Y 527.26 ± 201.10 (1,353) 1.11 ± 0.67 (3) 91.22 ± 44.34 (415) 1.36 ± 0.72 (6)
A/dk/VN/NCVD-712/2011 V424I 2.01 (5) 0.52 (2) 0.26 (1) NT
A/dk/VN/NCVD-714/2011 V424I 1.72 (4) 0.53 (2) 0.31(1) NT
Median
NA
0.41
0.32
0.2
0.23 ± 0.01§
2.3.4 A/ck/VN/NCVD-296/2009 I223T 10.99 ± 2.38 (7) 0.86 ± 0.33 (2) 0.52 ± 0.17 (2) 0.49 ± 0.24
A/ck/VN/NCVD-295/2009 I223T 10.37 ± 1.78 (6) 0.93 ± 0.19 (2) 0.50 ± 0.13 (2) 0.53 ± 0.18
A/ck/VN/NCVD-283/2009 I223T 11.36 ± 3.43 (7) 0.77 ± 0.28 (2) 0.49 ± 0.24 (2) 0.42 ± 0.16
A/dk/VN/NCVD-462/2010 G147R 6.76 ± 0.44 (4) 1.71 ± 0.48 (3) 0.45 ± 0.06 (2) 0.40 ± 0.17
Median
NA
1.62
0.51
0.31
0.12 ± 0.02§
1
H5N1 Reference viruses
A/VN/HN30408/2005, clone H275Y 155.18 ± 5.77 (1,552) 0.63 ± 0.12 (1) 10.88 (64) 1.13 (6)
A/VN/HN30408/2005, clone N295S 2.99 ± 0.21 (30) 0.73 (2) 0.13 (1) 0.52 (3)
A/Vietnam/1203/2004
NA
0.10 ± 0.02 (1)
0.46 ± 0.06
0.17 ± 0.03
0.18 ± 0.03
NA H1N1pdm09 Reference viruses
A/North Carolina/39/2009 H275Y 138.06 ± 26.02 (727) 0.19 ± 0.03 (1) 16.77 ± 4.47 (335) 0.26 ± 0.05 (1)
A/California/07/2009 0.19 ± 0.05 (1) 0.18 ± 0.02 0.05 ± 0.01 0.17 ± 0.04

* IC 50, 50% inhibitory concentration; NT, not tested; NA, not applicable.
†Compared with the neuraminidase gene sequence of the closest match. (See Table 1 for median IC50 for each clade.)
‡Fold increase compared with the median IC50 of the same clade virus.
§Fold increase compared with the IC50 of the closest matching virus in the same clade. Global Initiative on Sharing All Influenza Data NA accession no. shown in Technical Appendix 1.

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