Milestone - Scientists announced a major milestone in the fight against
and Disease - As our planet heats up, diseases once thought extinct,
along with other diseases previously unknown to humankind, gain a foothold
in temperate areas. Whatâ€™s in store for the United States this spring
and summer? And how can we protect ourselves against these emerging diseases?
Elsewhere on the web
Variation May Protect Against Malaria"— Reuters
Symposium on The Bio Safety of Genetically Modified Organisms
One of the world's biggest killers, malaria takes millions of lives each year
and that number is on the rise. But genetic engineers are working on modifying
mosquitoes so they can't transmit deadly diseases.
As this ScienCentral News video reports, malaria is their first priority.
is so rampant in many parts of the world that experts and health groups like
the World Health Organization and the National Institutes of Health are both
serious and hopeful about "genetic
control" of this disease. The most urgent situation is in Sub-Saharan
Africa, where malaria kills as many as a million children each year.
Malaria is spread by Anopheles mosquitoes, which transmit the tiny
Plasmodium parasites in their saliva when they bite people. Four of
the 150 known species of Plasmodiuminfect
humans, and 60 of the 380 known species of Anopheles mosquitoes
Genetic control advocates want to develop mosquitoes with genes that interfere
with the part of the parasite's
complex life cycle that takes place inside the mosquito. If such genetically-modified
or “transgenic” mosquitoes could compete and mate with wild mosquitoes
in malaria-ridden areas, they could make big dents in disease-spreading mosquito
"The weapons that we have to fight the disease right now are very limited,"
Jacobs-Lorena who leads the genetic control research at Clevelandâ€™s
Case Western Reserve University. "We have drugs and insecticides. Drugs
that kill the parasite, but as with bacteria that become resistant to antibiotics,
the malaria parasite is becoming resistant to the drugs that have been used,
and in the same vein, the mosquitoes are becoming resistant to insecticides
that are used to control their numbers."
"What is happening is that the number of malaria cases is increasing
rather than decreasing," Jacobs-Lorena says. "That's why it's so urgent
to find new approaches to fight the disease."
Jacobs-Lorena's group created modified mosquitoes in the lab with a single
artificial gene that impairs their ability to transmit malaria. The
research, published in the journal Nature, was a "proof of principle"—
it demonstrated that the idea could work.
The researchers discovered a small protein they dubbed "SM1" that
can attach to cells in the mosquito's stomach or gut and act as a barrier to
prevent the parasite from getting in. If the parasite never gets past the gut,
it will never reach the mosquito's salivary glands and the mosquito's bite is
rendered harmless. The scientists created a synthetic gene that codes for the
SM1 protein, and inserted it into mosquito eggs. As they hoped, the resulting
transgenic mosquitoes are no longer good at transmitting the parasite.
There remain many significant hurdles before field tests could even be considered,
says Jacobs-Lorena. "It will be very important to find other gene products
that can also interfere with the parasite development in the mosquito,"
Jacobs-Lorena says. "First of all, because this block is not 100 percent,
and second, because parasites can mutate to overcome this barrier, like it does
to become resistant to drugs," he explains. "This search will be greatly
enhanced… by the availability of the parasite genome and of the mosquito
Next, scientists would have to figure out a safe and reliable way to get the
gene to spread into wild mosquito populations. "It's work that is proceeding
in different laboratories, including ours," he says. "Several approaches
are being tried and it is not clear yet which one will work, so I would foresee
that it will take at least five or ten years until we have something that has
been perfected to the extent that it can be applied in the field."
"Then there's the psychological factor," Jacobs-Lorena says. "We
are talking about the release of genetically modified organisms in nature, and
understandably, people are concerned about this possibility." Indeed, he
admits, if the research does proceed to the point of planning field tests, public
opposition could be the ultimate hurdle. "One of the efforts that we have
to put into future research is to show that this approach is completely safe
and there is no harm to be done to any environment or to people by using transgenic
Jacobs-Lorena's research is funded by the National
Institutes of Health (NIH) and the World
Health Organization (WHO) Special Programme for Research and Training in Tropical