"This is the earliest version of the human immune system," says Flajnik. Sharks and humans share immune-system components like B cellswhich manufacture antibodiesand T-cells.
Baillie wondered whether sharks exposed to anthrax would produce robust anthrax-fighting antibodies. He provided Flajnik and Dooley with anthrax proteinswhich alone cannot cause diseasefrom his research in Great Britain.
Flajnik and Dooley used the proteins to immunize two nurse sharksa delicate procedure. Aquarium handlers in wet suits remove the sharks from their home tank and place them in a smaller one laced with anesthetic, which calms them. Then they are loaded onto a trolley for their injectionunder their skin near the fin.
"It's the equivalent to giving a TB shot in the arm," Dooley says. The sharks received booster shots at one-month intervals for the next three months.
Dooley and Flajnik took monthly blood samples from the sharks and found that with each successive booster the quantity of antibodies in the sharks' blood rose.
Back in the lab, the serum collected from shark blood reacts with the anthrax proteins to produce a bright yellow color.
"Ultimately, with this antibody you could see within a minute whether anthrax was present," Flajnik says.
The researchers have isolated the antibody that binds tightest to the anthrax protein and thus has the greatest potential for both diagnosis and treatment. They are currently determining its genetic sequence, which will help reveal how to mass-produce the antibody.
One day the antibody might even serve as a treatment for humans exposed to anthrax.
"The shark does all the hard work," Flajnik says. "It makes all these very specific, sturdy antibodies and all we have to do is analyze and use them."
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