Researchers may soon be able to predict whether a person will contract the flu virus before they exhibit any symptoms.
Duke specialists collaborated with researchers across the country in a study published in late August that highlighted differences in the immune system responses of seventeen paid volunteers who were exposed to a nonlethal strain of the flu, H3N2 Wisconsin. Scientists collected blood samples from the subjects and regularly monitored their response to the virus before and after exposure.
They recorded two kinds of responses, with two distinct gene expressions: nine subjects were symptomatic—those who showed symptoms and got sick after exposure to the virus–and eight asymptomatic–those who showed no symptoms at all after exposure. As a result of the research, scientists are searching for ways to tweak genes in order to strengthen resistance to the flu.
“We are the first people ever to look at which genes are actually being turned on and turned off in a timed course manner from the time of first exposure to the virus to time of getting sick,” said Dr. Micah McClain, assistant professor of medicine in the Department of Infectious Diseases.
Researchers were surprised by the high level of immune response in subjects who were asymptomatic.
“If you get sick, it’s not that your body just flushed it out or that the virus didn’t notice you. It’s that the body really mounts a very active host response,” said Dr. Alfred Hero, R. Jamison and Betty Williams Professor of Engineering at the University of Michigan. “This inflammatory response of genes stuck out like a sore thumb. We could see it just like a big stain on the image of the gene expression response in the blood.”
Hero said he believes there is a future for gene manipulation research—specifically “knock-out” experiments—in which specific genes are knocked out from the DNA of a mouse, which is then exposed to the virus in order to determine that “knocked-out” gene’s effect, or lack thereof, on the immune system’s response.
Many first-year students have already begun participating in a related flu study on the Marketplace’s second floor that looks into gene expression responses before and after a natural exposure—aided by the near constant contact of college students with each other—to the influenza virus. The researchers will compare the results of the students’ natural exposure to the virus to that of the participants in the August study.
“We ask students if they would like to be involved, they tell us when they start feeling sick, and then we go in and do a test,” McClain said. “At the same time we’re doing that, we ask their... close contacts if they would like to be in the study, because they are at a higher risk for getting sick, in the hopes that we pick up someone who gets sick naturally. It’s called an index cluster methodology. We identify the index case and then we sample people around them so that we can catch anyone who may get sick.”
Freshman Griffin Cooper, who is participating in the study, was tempted to participate due to the financial incentive as well as the opportunity to further the study.
“Well, as a college student, you’re very restricted on funds, so an opportunity to gain a few quick bucks is always good,” Cooper said. “But also it’s to help sick people out and fellow researchers out, especially at Duke, [being] the huge research facility that it is.”
McClain said people can use research on the flu in order to protect themselves from the virus.
“What people don’t understand is how common it is for people to be shedding the virus without ever showing symptoms. Half of the people in our study were asymptomatic,” he said. “Far and away, the most important thing people can do to avoid the flu is to get vaccinated.”
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