Science News Review

Why Some People Beat the Flu

Apr 2 at 8:08pm by Aileen

…and other people die

If your family managed to get through this year’s flu season intact, you’re probably considering yourself very lucky. The A strains claim tens of thousands of lives every year, while hundreds of thousands of people who get infected manage to bounce right back in a week or two. Researchers at the Helmholtz Center for Infection Research in Germany has conducted experiments using 7 strains of genetically identical mice that led the somewhat surprising conclusion that very serious infection and death from influenza is primarily an autoimmune malfunction.

The research, published in the Public Library of Science [PLoS-One] on line, demonstrates that an excessive immune response to the virus is responsible for fatal outcomes of the disease in mice, and that this immune overreaction is genetically linked.

After infecting mice from the seven genetic lineages with identical strains the Influenza A virus, the researchers were surprised to discover very strong differences in the progression of the disease. In five of the seven mouse lineages the illness was quite mild, while in two the animals lost weight rapidly and died within just a few days.

“The mice die from their own immune defenses, which are actually supposed to protect them against the virus,” says Klaus Schughart, head of the Experimental Mouse Genetics research group. “The immune system produces too many messengers, which have a strong activating effect on the immune cells. These cells then kill tissue cells in the lungs that are infected with the virus. It appears that the animals have specific receptors on their cells that make them more receptive to a severe viral infection.”

If the results can be extended by further research to humans, it may be possible to identify people who are much more likely to die of influenza due to specific genetic makeup, so that protecting them during flu season can be made a priority. While certain at-risk populations are advised to get their flu shots annually – including doctors and nurses most likely to be exposed to the virus – identifying who among the at-risk populations is most likely to develop a hyperactive and potentially fatal autoimmune response could make better use of flu vaccine supplies by targeting them to the right people.

Links:

Why Some People Shake Off the Flu
Host Genetic Background Strongly Influences the Response to Influenza A Virus Infections