Yale study suggests immune response to flu causes death in older people, not the virus

http://www.eurekalert.org/pub_releases/2016-04/yu-yss041816.php

Public Release: 21-Apr-2016
Yale study suggests immune response to flu causes death in older people, not the virus
Yale University

A new Yale-led study suggests that death from influenza virus in older people may be primarily caused by a damaging immune response to flu and not by the virus itself. The insight could lead to novel strategies for combating flu in the most vulnerable patients, said the researchers.

The study, published online April 21 in Science, demonstrates that replication of the flu virus alone is not enough to drive the deaths caused by seasonal flu, the researchers noted.

Ninety percent of the deaths attributed to flu each year worldwide occur in people aged 65 and older. To understand why older adults are more susceptible, the research team first observed the effect of flu infection on immune cells derived from young and older people. They found that the secretion of key antiviral proteins, known as interferons, was significantly reduced in older adults.

"It shows that older people may be more susceptible to influenza because they cannot mount an antiviral response," said Akiko Iwasaki, professor of immunobiology, investigator at the Howard Hughes Medical Institute, and the study's senior author.

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Specifically, they blocked genes that enable the immune system to detect flu, allowing the virus to replicate unchecked. They determined that inflammation was behind the damage that leads to flu deaths.

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