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Volume 23, Number 4—April 2017


Antiviral Drug–Resistant Influenza B Viruses Carrying H134N Substitution in Neuraminidase, Laos, February 2016

Tatiana Baranovich, Phengta Vongphrachanh, Pakapak Ketmayoon, Thongchanh Sisouk, Khampheng Chomlasack, Viengphone Khanthamaly, Ha Thuy Nguyen, Vasiliy P. Mishin, Henju Marjuki, John Barnes, Rebecca J. Garten, James Stevens, David Wentworth, and Larisa GubarevaComments to Author 
Author affiliations: Carter Consulting, Inc., Atlanta, Georgia, USA (T. Baranovich); World Health Organization Collaborating Center for Surveillance, Epidemiology and Control of Influenza, Atlanta (T. Baranovich, V. Khanthamaly, H.T. Nguyen, V.P. Mishin, H. Marjuki, J.R. Barnes, R.J. Garten, J. Stevens, D.E. Wentworth, L.V. Gubareva); Centers for Disease Control and Prevention, Atlanta (T. Baranovich, V. Khanthamaly, H.T. Nguyen, V.P. Mishin, H. Marjuki, J.R. Barnes, R.J. Garten, J. Stevens, D.E. Wentworth, L.V. Gubareva); National Center for Laboratory and Epidemiology, Vientiane, Laos (P. Vongphrachanh, P. Ketmayoon, T. Sisouk, K. Chomlasack); World Health Organization Emerging Disease Surveillance and Response Unit, Vientiane, Laos (P. Ketmayoon); Battelle Memorial Institute, Atlanta (H.T. Nguyen)

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Table 2

NA-H134N substitution–containing influenza B viruses that caused confirmed infection among 3 persons, Laos, February 2016*

Virus name, passage history§
Amino acid change in virus genes†

Patient information



Age, y/sex
Clinical pres.
Location, province
Date specimen collected
B/Laos/0406/2016 22/F SARI Vientiane Feb 9
Original N D/E Q


B/Laos/0525/2016 23/M ILI Champasack Feb 15
Original N A Q



B/Laos/0654/2016 3/F ILI Champasack Feb 25
Original N Q I
C1 N Q I

HA, hemagglutinin; ILI, influenza-like illness; M1, matrix protein 1; NA, neuraminidase; NS1, nonstructural protein 1; SARI, severe acute respiratory illness; –, indicates same amino acid residue as in the consensus sequence of B-Victoria viruses that were circulating in Laos during the 2015‒16 influenza season.
†Strain-specific amino acid sequence numbering is used. Sequences for all 8 gene segments were generated using the MiSeq sequencing system (Illumina Inc., San Diego, CA, USA) (14) (Technical Appendix Table 1). Data are amino acid differences in protein-coded regions of NA, HA, M1, and NS1 genes compared with the consensus sequence. Not shown: synonymous nucleotide mutations that were common for the NA-H134N viruses: PB1-c93t, PB1-g1930a, and HA-g1520a. In addition, NA-H134N viruses differed from each other by the following synonymous nucleotide mutations: B/Laos/0406/2016 possessed NS1-g345a, B/Laos/0525/2016 possessed NA-t762a, NS1-a561g, and B/Laos/0654/2016 possessed NS2-g186a.
‡Corresponds to position 219 in NS1 protein numbering used by Ma et al. (15).
§Original indicates specimen collected from patient; C1 and C2 indicates virus propagated once or 2 times on MDCK cells.
¶Presence of the NA-H134N substitution in the original respiratory specimens was confirmed by a pyrosequencing assay (see Figure 1) (Technical Appendix Table 2).

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