Mosquitoes bred to be unable
to infect people with the malaria parasite are an attractive approach to
helping curb one of the world’s most pressing public health issues, according
to University of California, Irvine (UCI) scientists.
Anthony James and colleagues
from UCI and the Pasteur Institute in Paris have
produced a model of the Anopheles
stephensi mosquito—a major source of malaria in India
and the Middle East—that impairs the
development of the malaria parasite. These mosquitoes, in turn, cannot transmit
the disease through their bites.
“Our group has made
significant advances with the creation of transgenic mosquitoes,” said James, a
UCI Distinguished Professor of microbiology & molecular genetics and
molecular biology & biochemistry. “But this is the first model of a malaria
vector with a genetic modification that can potentially exist in wild
populations and be transferred through generations without affecting their fitness.”
More than 40% of the world’s
population lives in areas where there is a risk of contracting malaria.
According to the Centers for Disease Control & Prevention, 300 million to
500 million cases of malaria occur each year, and nearly 1 million people die
of the disease annually—largely infants, young children and pregnant women,
most of them in Africa.
James said one advantage of
his group’s method is that it can be applied to the dozens of different
mosquito types that harbor and transmit the Plasmodium
falciparum parasite, including those in Africa.
Study results appear in an early online version of the Proceedings of the National Academy of Sciences.
The researchers conceived
their approach through mouse studies. Mice infected with the human form of
malaria create antibodies that kill the parasite. James’ team exploited the
molecular components of this mouse immune-system response and engineered genes
that could produce the same response in mosquitoes. In their model, antibodies
are released in genetically modified mosquitoes that render the parasite
harmless to others.
“We see a complete deletion
of the infectious version of the malaria parasite,” said James, a member of the
National Academy of Sciences. “This blocking process within the insect that
carries malaria can help significantly reduce human sickness and death.”
He and his colleagues have
pioneered the creation of genetically altered mosquitoes that limit the
transmission of dengue fever, malaria, and other vector-borne illnesses.
University of California, Irvine