Increasing Hemagglutination Inhibition Antibodies against Two Lineages
of Type B Influenza Virus in 2017-2018 Winter Season in Beijing, China
Abstract
Background Type B influenza virus circulates every year with lower
activity than that of influenza A virus in China. During 2017 to 2018
winter season, a sharp surge of influenza activity dominated by type
B/Yamagata lineage virus caused unprecedented medical burden in Beijing.
The research aimed to understand the underlying mechanism for this
circulation and be prepared for epidemics in the future. Methods Sera
samples collected from the patients in 2016-2017 and 2017-2018 flu
seasons were tested for profiling hemagglutinin inhibition (HI)
antibodies against both prevailing Victoria and Yamagata lineages of
type B influenza viruses. Results It showed that the positivity of HI
antibodies against both lineages of the virus in 2017-2018 winter was
higher than that in 2016-2017, while no difference of the positivity of
HI antibodies was observed between the two winter seasons. Meanwhile,
significant elevated geometric mean titer (GMT) against both lineages of
influenza B viruses was found in the specimens collected during
2017-2018 flu season than that from 2016-2017, suggesting the viruses
might undergo antigenic changes. These results also suggested that lower
GMT against both type B variants in 2016-2017 might serve as an
immunological niche for the dominating of B/Yamagata virus in China
during 2017-2018 winter season. Conclusions Our findings have
implication that vaccines including both lineages of influenza B virus
in formula might be a better preparation against influenza B epidemics.