Antibodies are immune molecules that have a key role in protecting against infection with influenza virus. The target of the protective antibodies is the influenza protein HA, which varies so dramatically among influenza viruses that it is used to classify them into subtypes (H1-H16).
It is thought that the antibodies generated by an individual’s immune system protect against only a few closely related influenza viruses. However, Antonio Lanzavecchia and colleagues, at the Institute for Research in Biomedicine, Switzerland, have now found that some individuals vaccinated with seasonal influenza vaccine containing H1 and H3 influenza viruses produce antibodies that can target H5 HA, the form of HA used by the deadly H5N1 avian influenza virus.
Although these antibodies protected mice from a recent swine-origin pandemic H1N1 influenza virus and several H5N1 influenza viruses, the authors note that more work needs to be done to determine whether individuals produce these antibodies at high enough levels to provide them with protection from infection by different influenza virus subtypes and how vaccination might promote their high level production.
Title: Heterosubtypic neutralizing antibodies are produced by individuals immunized with a seasonal influenza vaccine.