Table 3 Amino acid substitutions found on the HA protein of influenza B viruses.

From: Molecular evolution of influenza B virus during 2011–2017 in Chaoyang, Beijing, suggesting the free influenza vaccine policy

Influenza virus lineages

Epitope

Surveillance seasonsa

Mutationb

B/Victoria-lineage

120-loop (116–137)

2011–2012

N129S (5/21)

2015–2017

I117V (23/29), N129D (29/29)

150-loop (141–150)

2011–2012

I146V (21/21)

B/Yamagata-lineage

120-loop (116–137)

2013–2015

N116K (43/44)

  1. aOnly amino acid substitutions shared by 50% of viruses or more in every season are reported in this table. Substitutions are compared with recommended vaccine strains in the same year. bThe frequency was the number of influenza viruses having the substitution to all the strains of influenza B virus in surveillance seasons.
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