A universal flu vaccine?
Via a news alert on Science Daily, which reports research done at Imperial College London, some data which suggests that annual flu shots might become something of the past. Influenza viruses are notorious for their genetic flexibility, and protection afforded either by vaccination or by actually suffering through and recovering from the flu does not offer appreciable resistance to influenza strains that arise in the future.
The study reported in this news alert recruited subjects to follow over several consecutive flu seasons, to see how individual flu experiences correlated with immune system function. Blood was drawn from the subjects at the start of the 2009 “swine” flu pandemic, and they reported any flu-like symptoms through the end of the 2011 seasonal flu outbreak. What was found was that patients who reported more severe flu symptoms through the study had lower levels of T-cytotoxic (CD8) cells in their blood; these are the cells that are actively fighting a viral infection when it is underway, but they are not the immune cells that are generally activated by standard vaccination procedures. In contrast, patients with elevated levels of the CD8 cells had greatly diminished to non-existent disease.
Influenza vaccines cause the immune system to produce antibodies against the virus antigens, and this process uses a different type of immune cell (CD4 cells). Since the virus antigens change from year to year, antibodies from one year’s vaccine do not protect in the subsequent annual outbreaks. Because the CD8 cells recognize core components of the virus during an active infection, these do not change with the same regularity and therefore might offer an opportunity for developing a novel approach to prevent the disease in the first place.
The research suggests that new vaccine approaches should cause the immune system to produce more CD8 immune cells instead of the usual CD4 cells to target influenza virus infections as they begin to occur. By analyzing what allowed the patients in this study to develop these types of immune cells naturally, it can suggest approaches to promoting this via a vaccine.