Blood stains the walls of the cage where the deadly creatures are kept.
They look agitated and eager to escape, but they've just been fed, and David A. O'Brochta figures it's safe to stick his hand inside. Normally they would bite. Especially if you're a person. Put yourself in a room full of cows, and these things will single you out, O'Brochta says.
Not on this day, however, and not in this new University of Maryland biotech laboratory in Rockville. At the moment, the hundreds of captive Anopheles gambiae mosquitoes, the kind that most often infect people with deadly malaria parasites, are not hungry.
But they will be soon. And that will never change. So O'Brochta, head of the lab's new Insect Transformation Facility, is trying to change something else about Anopheles gambiae to prevent it from claiming a million lives a year.
O'Brochta creates mutant insects.
Not the kind in the horror movies that grow 30 feet tall and menace the city.
He's trying to create the kind whose genes have been tweaked just enough, in just the right way that the insect's bad habits are made benign. Just enough so that it can't harbor the parasite.
That is not easy: Anopheles gambiae is about as small as an eyelash. Hundreds of its minute, gray, banana-shaped eggs resemble a pinch of gunpowder.
But the state-of-the art lab, which made its debut last month, is designed and equipped for the microscopic tasks of gene-tweaking. Injections into mosquito eggs are done with a quartz glass needle the size of a strand of hair.
‘We’re building a bug’
"We're building a bug," in much the way inventors would design a new airplane, says O'Brochta, 51, an insect molecular geneticist. "We know we can do it."
The new lab, the only one of its kind in the world, has been designed to perfect the process.
The lab has an insectary where mosquitoes such as Anopheles gambiae and Aedes aegypti, which can carry yellow fever, are reared in warm, humid chambers that look like walk-in freezers.
There's also a vivarium, an enclosure in which technicians raise the lab mice used to feed the mosquitoes. "We used to use graduate students," O'Brochta jokes.
A mouse is first anesthetized, then laid on the mesh cover of a mosquito cage for about five minutes so the insects can dine. The technicians are careful. If the mouse is left too long, or if there are too many mosquitoes, the mouse could be "exsanguinated," or drained of blood.
Female mosquitoes — the ones that bite — require "blood meals" every few days to nourish their eggs, and it is their excretions that stain the plastic buckets in which they are kept. After the feeding, the mouse is removed, revived and "given a two-week vacation" to replenish its blood supply, O'Brochta says.
‘Flying syringe’
None of the feeding mosquitoes is infected with pathogens that cause disease, he says. And the mice don't develop mosquito "bites" as humans do. But Anopheles gambiae remains a "flying syringe," O'Brochta says, and a superb vector for Plasmodium falciparum, the deadliest form of the parasite that causes malaria.
The mosquito picks up the parasite by biting an infected person. The parasite mates and produces offspring that are deposited in the next person the insect bites. The insect's taste for people is baffling. "They smell us," O'Brochta says. "They specialize on us." It is not clear why.
But the cycle is devastating. Malaria is believed to have killed more people than all the wars and other illnesses combined.
The Washington region, now malaria-free, once harbored the disease, and George Washington and Abraham Lincoln are believed to have had it. Malaria is thought to have killed Dante, Saint Augustine and Genghis Khan and to have sickened Mother Teresa, Ho Chi Minh and Christopher Columbus.
"Nothing really tops malaria in terms of an insect-borne disease, in terms of deaths," O'Brochta says, sitting in a conference room near his lab. Nowadays, those it kills are "mostly kids in Africa, under the age of 5."
‘It’s getting worse’
"The magnitude of the problem really hasn't changed in decades," he says. "In fact, it's getting worse. The number of deaths from malaria is actually going up worldwide, not going down, which is kind of a startling statistic in this day and age."
Although drugs to combat the disease exist, economics and politics, along with drug and insecticide resistance, have hampered the fight, O'Brochta says. There is no malaria vaccine, he says. Scientists at Walter Reed Army Institute of Research in Silver Spring and scores of their colleagues elsewhere are seeking to develop one.
O'Brochta's work, along with the work of others around the world, has focused on breaking the disease cycle by altering the characteristics of the mosquito. And much of that focus is on the mosquito's ability to harbor the parasite.
"Most mosquitoes in Africa do not serve as a host for Plasmodium falciparum ," O'Brochta says. "The ability to serve as a host for malaria parasites is a very narrow, restricted trait." So the question is: Could Anopheles gambiae be made to resist the parasite?
"That's kind of the big idea," he says. Science has learned how to alter the mosquito's genome and has learned, roughly, which gene to add to make it resist the parasite, O'Brochta says.
But this new mosquito must also be made able to transmit the beneficial traits rapidly among the rest of its population. And that part has been difficult to engineer. "With mosquitoes, we've had virtually no success," he says.
One day last week, O'Brochta and his research colleagues, Robert A. Harrell II, 39, and Channa Aluvihare, 40, were running tests to make sure their procedures and equipment worked. They were injecting mosquito eggs with genetic material that would make the mature mosquitoes glow under ultraviolet light. It had worked before, and they hoped to repeat the process.
Aluvihare used a plastic tube to suck about 20 mosquitoes out of a cage. He placed them in a vial and put the vial in a darkened incubator, where they would lay eggs. Harrell then performed the injections.
Predictable outcome — in part
As the men peered into microscopes, a mosquito trap whirred on a counter nearby. Although none of the insects is infected, the workers didn't want escapees buzzing around. No transgenic insects have ever been released in the wild.
It's not that the mutants would be dangerous.
"You're not going to just, all of a sudden, produce huge, huge insects out of these," Harrell said.
The scientists pretty much know the outcome of the genetic changes they're making. "It's not just, throw something in, and 'Let's see what this does,' " Harrell said. "We're not really creating monsters."
But the bug builders can't know everything.
"As a scientist, you're never going to know all the outcomes," O'Brochta says. "We need to know what the risks are, and then we need to be able to manage those risks. . . . Unfortunately, people demand that we often know everything. But when you think about it for more than really just a minute, I think, we realize that . . . [with] everything we do, there's a degree of uncertainty, and there's risk involved."
