Electron micrograph of flu virus. (Credit: CDC Source)
Top Science of 2009
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Check out the whole list here
In celebration of the approaching New Year, I present a list of my most popular science stories of 2009. Taken from the vast expanse of all fields of science, they may not be everyone's top ten, but they are among the top news makers and will have repercussions well past the ending days of 2009.
For most, the flu is an annoyance: the cough, the achy muscles, the fever. But for others, the virus is deadly. When Drs. Kate Sullivan and Meredith Heltzer investigated the difference between individual flu responses, their results were surprising. A person's immune system wasn't the key to the puzzle, it was the virus itself.
“The most important find in the paper is that influenza is pretty clever virus,” says Sullivan, who works at Children’s Hospital of Philadelphia, Pennsylvania . “It essentially outwits the immune system”
It does more than outwit. Heltzer and Sullivan found that the flu virus is capable of 'paralyzing' the immune system, compromising it in such a way that it struggles to meet the threat of other infections. They believe this paralysis is why many who die of influenza often die due to the added complication of a bacterial infection such as pneumonia. This finding has finally offered some evidence for a case that has long puzzled infectious disease researchers.
“We knew that people with influenza came down with [pneumonia]. But we didn't know why,” says Sullivan. “Some people thought it was the mucus, that if have a lot of mucus you are more likely to get a bacterial infection. Some thought that the airways were damaged” so it was harder to get the bacteria clear of the body.
When a disease affects people differently, often researchers will search for a reason inside the immune system. After all, every person is being infected with the same virus, so the difference must lie in the individual being infected. Armed with that hypothesis, Helzter met patients coming into Boston's Children's Hospital with flu-like symptoms, splitting them into two groups: those who easily beat the illness and those who ended up in intensive care. She drew plasma samples from each group, and took the sample back to the lab for testing.
“[We asked] how sturdy are [the immune cells], how well can they respond to a second threat?” Sullivan says. “Are the cells still able to respond to threats? And the answer was no, they really weren't.”
Heltzer was looking for something distinctly different in the samples drawn from those who were severely ill. But the actual answer was not in the immune system—it was in the virus. When the flu enters the body, it quiets the toll-like receptors which are responsible for sending the immune system out to deal with a new threat. Regardless of if a person has perfectly healthy immune system or one that is not as strong, everyone will be affected by this flu virus trick around the body's defenses.
But what about the different responses? After all, there are still those who recover from the flu without much fuss even though the immune system has been compromised. Sullivan says that their data points towards the amount of virus a person is infected with seems to cause the difference. The more someone has in his body, the more likely the immune system will be paralyzed. However, more research is needed to validate the theory.
Regardless, Sullivan is please with the work that was done. It was not the result they were expecting, but the research did illuminate an important facet of a deadly disease.
“We're excited,” she says. “We think [this is] going to actually translate into something that is meaningful for people, and that was our goal all along.”
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