The pandemic 2009
H1N1 vaccine can generate antibodies in vaccinated individuals not only against
the H1N1 virus, but also against other influenza virus strains including H5N1
and H3N2.
This discovery adds an important new dimension to
the finding last year that people infected with pandemic 2009 H1N1 virus
produced high levels of antibodies that were broadly cross-reactive against a
variety of flu strains.
Development of a "universal" influenza vaccine that
protects against multiple viral subtypes has long been the goal of
immunologists working to overcome the requirement for a new vaccine during
each flu season and
the need for a rapid response to potentially dangerous mutations.
The new discovery brings the researchers closer to
being able to design a pan-influenza vaccine that reliably induces broadly
cross-reactive antibodies at sufficiently high levels to protect against
different influenza subtypes.
The findings are published this week in the Proceedings
of the National Academy of Sciences (PNAS).
The researchers are from Emory University, the
University of Chicago, and the National Institute of Allergy and Infectious
Diseases (NIAID) of the National Institutes of Health (NIH).
The researchers analyzed B cell (antibody)
responses in 24 healthy adults immunized with the inactivated pandemic 2009
H1N1 vaccine. Vaccination caused a rapid increase in production of monoclonal
antibodies that were capable of neutralizing multiple flu strains.
Three of the antibody types also were able to stick
to the "stalk" region of the virus that does not change as much as
other regions and thus could provide a basis for a vaccine with broader and
more reliable protection.
Antibodies that are broadly reactive against
multiple influenza strains are rarely seen in people after infection or
vaccination with seasonal flu, the authors note. In the 24 vaccinated
individuals in the current study, the majority of flu antibodies neutralized
more than one influenza
strain and also seemed to be the result of B-cell memory resulting
from previous exposure to other flu strains.
"Since discovering last year that people
infected with the H1N1 2009 virus produced antibodies against multiple flu
strains, our goal has been to test this ability in vaccinated
individuals," says senior author Rafi Ahmed, PhD, director of the Emory
Vaccine Center and a Georgia Research Alliance Eminent Scholar.
"Our new finding is a key step in the
development of a vaccine that can produce high levels of antibodies that
protect against multiple flu strains, including challenging mutations that have
the potential for widespread illness and death."
The next step for the research team will be to
improve on their results and develop a vaccine that produces high levels of
antibodies and can reliably protect against multiple flu subtypes.
Provided by Emory University
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