A recent study suggests that the
development of vaccines that protect against multiple strains of Influenza A
Virus (IAV) on a long-term scale is possible.1
If you
have ever stayed home from school or work with a sudden fever, cough, sore
throat, and generally achiness, you probably had the flu. You may have even
gotten the flu shot, but influenza still got the best of you. Vaccination for
the flu is difficult, because the virus mutates and develops different strains
all the time.2 The flu shot or nasal mist that we use to prevent
influenza is typically trivalent, which means it has the ability to protect
against three specific flu strains.3 These strains change depending
on what scientists predict will be the most dangerous strains to the public
that year.3 Obviously, an ideal vaccine would protect against any
form of the flu. For this reason, research that shows how CD8 T cells can be
cross-protective against heterosubtypic infections is especially promising.
The goal
of the study was to better understand the effects of vaccination on the way the
immune system responds to infection with IAV. Influenza A virus is found in
both animals and humans. It is also generally responsible for seasonal flu
epidemics in humans.4 The most at risk individuals are children, the
elderly, and other people with weakened immune systems. Influenza is
responsible for between three thousand and forty-nine thousand deaths per year,
as well as up to two hundred thousand hospital visits.4
In order
to understand the methods and
results of the experiment, one must have a basic
understanding of certain components of the immune system, as well as specific
terms and phrases that are important in the study.
CD8
T cells are cytotoxic cells that specifically terminate the acute influenza
infection and contribute to long-term memory of the virus.1 Virus-like
particles (VLP) are developed from influenza virus proteins, but they do not
contain IAV genomic material.1 This means that resemble the actual
virus, but they are replication deficient. Because of this characteristic, VLPs
have a greater potential for use in the vaccination of high influenza risk
individuals.1 Lung-draining lymph nodes (dLNs) are the part of the
body in which naïve CD8 T cells are primed. The cells then leave the dLNs when
they migrate to the lungs (the site of infection with IAV).
The
study conducted by Hemann, Kang, and Legge made many comparisons between
control mice and mice that were vaccinated with VLPs prior to IAV infection.
The experiment was broken up into several different parts in order to show how
different aspects of immunity contributed to their overall determination.