December 8, 2008

DESIGNING INSECTS:

The Scientist Ending Malaria with His Army of Mosquitoes: For decades scientists have been chasing a genetically engineered vaccine that would prevent the one million deaths that occur from malaria every year. Stephen Hoffman thinks he's found a better one -- in the mosquitoes themselves. (Jason Fagone, 12/08/08, Esquire)

It turns out, though, that there is a way to disrupt the life cycle of the parasite. If a scientist zaps one of these mosquitoes with gamma radiation, the parasites inside it become weakened. If this irradiated mosquito bites you, the parasites travel to your liver, same as before. But now they just sit there. They don't cause you any harm, because they never multiply into an army or hatch into your blood. And yet the parasites--as the scientist can't help but notice--are still alive, meaning that, in theory, they're capable of priming an immune response. Which is how vaccines have worked for more than two hundred years, going all the way back to Edward Jenner's discovery that when he scraped some fluid from a cowpox blister into a cut on a little boy's arm, that boy was protected against smallpox.

But how can the scientist be sure that the things inside this live mosquito--these shocked, "attenuated" parasites--could truly provide protection against malaria?

If the scientist is Stephen Hoffman, he takes a small can and fills it with three hundred irradiated mosquitoes. He inverts the can, placing the mesh lid against his bare forearm, and a cloth over his arm to simulate night. He begins to feel a tickling sensation. Three thousand bites later, he withdraws the can. He has "vaccinated" himself. Then, two weeks later, he repeats the process, only with infectious mosquitoes instead of benign ones, and . . . waits.

In his thirty-year career in tropical medicine, twenty-one of those in crisp Navy whites, Hoffman, sixty, has always been a dreamer. He trudged through the Colombian jungle while in medical school in search of a witch doctor and indigenous salves. Years later he traveled to the remote Indonesian island of Flores, rigging up a twelve-volt battery to a field incubator so he could test the native strains of malaria for resistance to drugs. He escaped death twice: first when a bout of typhoid fever in Ecuador roasted his body for days like a self-basting turkey, then again, fifteen years later, when he and his wife walked away from a plane crash in rural Kenya, where they had been studying malaria in indigenous people. Yet he didn't put the can to his arm out of some sense of romance or dare. He did it because he had already tried to make and test a vaccine using more mainstream methods, and he had failed.

During the eighties at the Naval Medical Research Institute in Bethesda, Maryland, Hoffman's job was to make a malaria vaccine for marines deployed abroad. The era of genetic engineering was dawning, and Hoffman and his colleagues spliced and cloned loops of DNA. Once they had created a "recombinant" vaccine they liked, they shot it into their bodies, then used the can and the mesh and the cloth to give themselves a chaser full of parasites.

Two weeks later, Hoffman was speaking at a medical conference when, in midsentence, he felt a wave of coldness snap through his limbs, deep and sharp, and he lost control of his body. He staggered to a chair and sat down, his teeth chattering uncontrollably. This was a malarial "rigor," his body's vain attempt to boil away the parasite now bursting his red blood cells.

For years afterward, Hoffman kept trying to refine the recombinant vaccine.

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Posted by Orrin Judd at December 8, 2008 8:53 AM
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