Multiple viral introductions: molecular characterization
of inﬂuenza B virus in Wenzhou, Zhejiang, China, from 2011
to 2014 based on hemagglutinin and neuraminidase genes
Received: 1 November 2015 / Accepted: 8 December 2015 / Published online: 2 January 2016
Ó The Author(s) 2015. This article is published with open access at Springerlink.com
Abstract Inﬂuenza B virus is a major causative agent of
respiratory disease in humans. Our study of an outbreak of
inﬂuenza B virus in Wenzhou from 2011 to 2014 revealed
that 163 (5.58 %) of 2921 samples were inﬂuenza B pos-
itive. Sequencing of the hemagglutinin and neuraminidase
genes showed substitutions at the amino acid level. Phy-
logenetic analysis revealed co-circulation of the B/Victoria
and B/Yamagata lineages in the Wenzhou area from 2011
to 2014. Multiple viral introductions from both Chinese
and international sources played important roles in ende-
mic co-circulation and transmission in coastal southeastern
Keywords Inﬂuenza B virus Á Molecular epidemiology Á
Phylogenetic Á Victoria Á Yamagata
Inﬂuenza B virus has been a major pathogen in seasonal
inﬂuenza outbreaks and has caused respiratory infections in
humans globally. It was ﬁrst isolated in 1940 during an
epidemic in the USA (B/Lee/40). Inﬂuenza B virus is a
member of the family Orthomyxoviridae and is closely
related to inﬂuenza A viruses, which are similar in viral
structure, genome organization and epidemiology [1–4].
Inﬂuenza B virus differs from inﬂuenza A virus, which has
a diversity of subtypes according to surface glycoproteins,
in having no subtypes, but it has been separated into two
main antigenically distinct lineages, Victoria (B/Victoria/2/
87-like) and Yamagata (B/Yamagata/16/88-like), since
1983, based on an analysis of the hemagglutinin gene .
Many studies have reported both types to have been pre-
dominant during different periods and in different geo-
graphic regions worldwide [2, 6, 7].
Wenzhou, a city in southeastern Zhejiang Province,
China, includes four districts and 10 counties and is one of
the important economic and business centers in Zhejiang.
Infectious diseases such as pandemic H1N1 and foot-and-
mouth disease have been monitored in Wenzhou, and
several outbreaks of these pathogen-caused illnesses were
dealt with during the last decade according to surveillance
systems established by public health departments in China.
Inﬂuenza B has now become one of the major public-health
problems, as there have been many sporadic cases in recent
years. Mutations in both the hemagglutinin (HA) and
neuraminidase (NA) genes have allowed inﬂuenza B virus
to circumvent the immune response in humans, to persist in
human populations, to circulate in an endemic environ-
ment, and to cause recurrent seasonal epidemics [8–11].
Therefore, by combining the results of molecular and
phylogenetic data, we attempted to determine (1) the
D. Chen and X. Wen contributed equally.
Electronic supplementary material The online version of this
article (doi:10.1007/s00705-015-2721-7) contains supplementary
material, which is available to authorized users.
& Yi Sun
Wenzhou Center for Disease Control and Prevention,
Wenzhou, Zhejiang, China
First People’s Hospital of Huzhou, Huzhou Teachers College,
Huzhou, Zhejiang, China
Zhejiang Provincial Center for Disease Control and
Prevention, 3399 Binsheng Road,
Hangzhou 310051, Zhejiang, China
Arch Virol (2016) 161:1005–1013