Genes May Explain Who Gets Sick From Flu

In the February 25 Issue:

Genes may explain who gets sick from flu

Infection can activate two dramatically different responses

By Tina Hesman Saey

September 24th, 2011; Vol.180 #7 (p. 15)

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The difference between staying well and suffering days of misery depends on which of two contradictory ways the immune system reacts to infection by the flu. One strong reaction releases inflammatory chemicals leading to sickness, researchers report online August 25 in PLoS Genetics. An equally strong but opposite reaction produces anti-inflammatory compounds and fights off the flu without producing symptoms.

Most of what researchers know about influenza’s effect on people comes from studies of people who are already sick. But Alfred Hero and his colleagues wanted to know how some people seem to be able to avoid getting sick. The researchers infected 17 volunteers with a strain of seasonal flu called H3N2/Wisconsin.

Nine of the volunteers got sick. Some of the others reported feeling under the weather, but had no clinically discernible symptoms. The researchers drew blood before the flu inoculation and every eight hours for five days after the initial infection. The team then examined the activity of about 22,000 genes in each blood sample.

“The persistent patterns that came out of this were striking to say the least,” says Hero, a computer scientist and electrical engineer at the University of Michigan Medical School.

Gene activity patterns could predict up to 36 hours before symptoms peaked how sick people would get, the researchers found. Those who got sick activated immune chemicals that trigger inflammation and stress responses. “In asymptomatic people the immune response is just as active, but dramatically different in nature,” Hero says. People who stayed well not only repressed the stress response, but also activated anti-inflammation and antioxidant genes.

“This is really exciting data,” says Octavio Ramilo, the head of pediatric infectious diseases at Nationwide Children’s Hospital in Columbus, Ohio. The study illustrates that gene activity analysis may help doctors determine which patients are most in danger of getting seriously ill. But the current study hasn’t put the entire story together yet, he says. Researchers still need to determine whether the different patterns of responses depend upon the person’s genetic makeup, properties of the virus or other factors. Hero adds that the people in the study may react differently to other flu strains or even to the same one under different circumstances.

The technology may one day help doctors diagnose which viruses are infecting babies with fevers and predict which infants will end up in the intensive care unit and which ones can go home.

Such tests may also be important public health tools for preventing flu pandemics, Ramilo says. People who stayed well tended to spread fewer flu viruses than people who got sick, the study showed. So health care workers might be able to test people exposed to a virus and determine from gene activity patterns who needs to be quarantined to limit the spread of infectious diseases.

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Comments 6

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Tina ended: So health care workers might be able to test people exposed to a virus and determine from gene activity patterns who needs to be quarantined to limit the spread of infectious diseases.

I doubt this will be the case, since more research will likely reveal that the phenomenon occurs differentially in the various ethic or racial groups. I doubt we will see quarantine, when it means more of one racial group than another will be recommended to do so. But that is because our ethical views are 70 years behind the science. It isn't a flaw on the part of the science.

Israel Dix

Aug. 26, 2011 at 9:22am
I agree. But instead of drastic action of like putting thousands of (possibly) ethnically similar people under quarintine year after year, we should test everyone, once, early in life for the flu susceptibility discussed in the article. People who need annual flu shots will know for sure they need one, and those who don't can finally tell their spouses to stop nagging them about it.

Robert Alderman

Aug. 26, 2011 at 1:07pm
The picture of these two kinds of immune responses, apparently so different, suggests a more complex situation yet to be elucidated.

Meanwhile, I don't see how considerations of "race" or ethnicity got mixed up with this story. I suspect any mention of quarantine was nothing more than speculation about some hypothetical mega-pandemic scenario, involving such large numbers of sick people that temporary triage measures would become necessary.

Ralph Dratman

Aug. 29, 2011 at 9:26am
I had a friend, Jean Hunt, whom I met through an archaeology article she published in the "Mensa Bulletin," of October. 1989. She was my age, 56 at that time, but had a reaction to a flu shot in November, 1992. She was briefly hospitalized, but was re-admitted in February, 1993, and died of pneumonia.

Gerald Baker

Aug. 29, 2011 at 9:26am
A healthy human body is a capable of some extraordinary feats. It can maintain a continual heartbeat throughout life. It has lungs that breath without prompting. It has an amazingly complicated brain that allows for the most basic functioning, while having the potential to create breathtaking pieces of art, dissect the most complex scientific principles and imagine the unimaginable. One of the most astounding aspects of the human body is its ability to protect itself. Through a dynamic system of mechanisms, the body can defend itself against disease and illness by recognizing and destroying pathogens, viruses and toxins that invade the body. This structure of protection is called the immune system, and it works every day to keep the body healthy and functioning.

The immune system contains a network of proteins, tissues, organs and cells that work together to defend and attack organism and other invaders, called antigens, that can harm the body. The cells involved in the immune system are called leukocytes, or white blood cells. There are two types of leukocytes, phagocytes and lymphocytes, and each has a distinct role in the immune process. The phagocytes are the cells that ingest harmful substances in the body, like dead cells, bacteria or toxins. Lymphocytes, which are either T cells or B cells, are a vital part of immune functioning as they recognize any previous contact with invading antigens. B cells create antibodies, proteins that latch onto specific antigens, neutralize the antigens, while T cells destroy them. Lymphocytes have the ability to adapt to changes in the structure of these harmful invaders. there ia much more on this topic at Newsonhealthcare.com

ken lyn

Aug. 29, 2011 at 3:54pm
I had read another article that suggested older humans and archaic humans interbred in Africa. They suggested that the some of the genes are still here, today, and could have beneficial affects from disease.
--University of Arizona geneticist Michael Hammer and a team of evolutionary biologists, geneticists and mathematicians report the finding in today's Proceedings of the National Academy of Sciences.--

Dragon

Sep. 8, 2011 at 10:39am

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