Duke. Singapore: An analysis of 10 years’ worth of data on human influenza B viruses
has shed new light on the pathogen which can cause the seasonal flu.
Findings from this study could help make flu immunization programs more
effective; by better targeting vaccines or by eventually eliminating one
of the flu lineages completely.
What are Influenza B viruses?
Influenza epidemics seriously affect populations worldwide, with an
estimated three to five million cases of severe illness and 250,000 to
500,000 deaths, yearly. Four influenza virus lineages co-circulate in
the human population to cause seasonal epidemics. Of the four, two are
influenza A and two are influenza B virus lineages, named Victoria and
Yamagata. To date, most studies have focused on the influenza A virus
lineages because they are the more commonly circulating lineages in
humans which have also caused occasional pandemics.
A new study, led by Assistant Professor Vijay Dhanasekaran and
Associate Professor Gavin Smith from Duke-NUS Graduate Medical School
(Duke-NUS), has presented the largest comparative analysis of human
influenza B viruses undertaken to date. Results were achieved using
advanced computational methodologies to analyze genomic data of the
pathogen taken from human hosts. Significantly, this study is also the
first to integrate demographic information such as the host’s age.
Findings offer new insight into the evolution and epidemiology of
this highly infectious virus, and reveal how the two influenza B virus
lineages fundamentally differ from each other and from the influenza A
virus lineages.
Flu Vaccine Implications
“Our research shows that school aged children are more susceptible
than adults to influenza B virus lineages, especially the Victoria
lineage,” explained first author Asst Prof Dhanasekaran from the
Emerging Infectious Diseases Program at Duke-NUS. “This younger
population should be targeted for the use of the quadrivalent influenza
vaccines.”
Commonly administered influenza vaccines are generally composed of
two influenza A lineage viruses - but only one influenza B lineage
virus. Recently, quadrivalent influenza vaccines, which target all four
lineages, have been approved for use. However, they are significantly
more difficult to prepare, more expensive and have limited availability.
This new study shows that it may be important to use these vaccines for
a specific population.
Virus Eradication through Vaccination
The research team also ventures that a re-evaluation of influenza B
vaccination strategies may have long term benefits in controlling the
flu in the human population. Influenza B Yamagata viruses evolve at a
much slower than influenza B Victoria viruses.
If the administration of the quadrivalent influenza vaccine was
expanded sufficiently - it may be possible to eradicate the slower
Yamagata lineage from humans. This would signify a major step towards
triumph in influenza control and allow the return to an effective
trivalent influenza vaccine, sometime in the future, which would target
the remaining three flu virus lineages.
International Team Led the Breakthrough
The study was authored by a group of international scientists from
Australia, New Zealand, the United States, Switzerland and Singapore and
marked a major collaboration between Duke-NUS and the Bioinformatics
Institute (BII), Agency for Science, Technology and Research (A*STAR).
The next step for this team is to better understand the underlying cause
of differences in patient age, using laboratory experiments.
Published this past weekend in the journal eLife, the study was
supported by grants from the US National Institutes of Health, the
Australian Government Department of Health and Ageing, the Swiss
National Science Foundation, the Australian National Health and Medical
Research Council and A*STAR joint grant (12/1/06/24/5793), the Singapore
Ministry of Health’s National Medical Research Council under its
Individual Research Grant (NMRC/GMS/1251/2010), the Singapore Ministry
of Education Academic Research Fund Tier 2 grant (MOE2011-T2-2-049) and
the Duke-NUS Signature Research Program, with funding from the Singapore
Ministry of Health and A*STAR.
The full text of the study “The contrasting phylodynamics of human
influenza B viruses” can be found on the eLife website at the following
link: http://dx.doi.org/10.7554/eLife.05055.