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SCIENCETuesday 1 December 2015
Using new gene drive to create malaria-resistant mosquitoes
LAURAN NEERGAARD line in Proceedings of the them unable to infect peo- or reverse pesticide resis- iting the malaria protection
National Academy of Sci- ple. tance in weeds, or sup- by targeting the change to
AP Medical Writer ences adds some urgency. James engineered immune press insect populations. a specific spot in the mos-
“This work suggests that system genes that could The idea comes from a few quito’s reproductive DNA.
WASHINGTON (AP) — Cali- we’re a hop, skip and jump spur a mosquito’s body to examples in nature where To measure, they tacked
away from actual gene develop antibodies to at- certain genes spread dis- on a fluorescence gene
fornia researchers hatched drive candidates for even- tack the parasite, so that it proportionately, and scien- that made mosquitoes’
tual release” in nature, he couldn’t transmit the infec- tists have longed for a way eyes look red if they har-
some malaria-resistant said. tion. The new genes worked to control that process. Re- bored the new gene.
Malaria kills more than half as intended when injected cently they’ve had some
mosquitoes and then gave a million people a year, into the eggs of a particu- success using a powerful The malaria protection
mostly children in Africa, lar malaria-spreading mos- new tool named CRISPR- spread remarkably well,
evolution a shove — using proving the concept even
though far more work is
a groundbreaking technol- needed before this kind of
mosquito could be tested
ogy to ensure the insects in the wild, James said.
Among the findings to be
pass on that protective addressed was that the
transgenic male mosqui-
gene as they reproduce, toes passed their new trait
to the next generation
with implications far be- more efficiently than trans-
genic females did.
yond the promise of fight- Gene drive experiments
are controversial. One
ing malaria. worry is the possibility of
altered organisms escap-
The experiment reported This photo provided by the Centers for Disease Control and Prevention (CDC ) shows a feeding ing the laboratory before
Monday involves what’s female Anopheles stephensi mosquito crouching forward and downward on her forelegs on a hu- scientists know how to use
called a “gene drive,” a man skin surface, in the process of obtaining its blood meal through its sharp, needle-like labrum, them. The California team
technique that, if it pans which it had inserted into its human host. took safeguards including
out, promises to alter the special lab security and us-
genetics of populations of Associated Press ing a mosquito species that
insects and certain plants can’t survive in California’s
and animals faster than and sickens about 200 mil- quito species, Anopheles Cas9 that allows precise climate.
Mother Nature could. lion more. Mosquitoes pick stephensi. editing of DNA in living Additional questions in-
Normally, genes have a up the parasite by biting cells, sort of like cut-and- volve what’s appropriate
50-50 chance of being in- an infected person, and Altered mosquitoes would paste software. to try — wiping out a spe-
herited. University of Cali- spread it when they bite have to gradually spread Earlier this year, University cies or just altering it, for
fornia researchers created someone else. Mosquito- their new genes by mating of California, San Diego, bi- example — and how to
a strain of mosquitoes that killing insecticides and bed with wild mosquito popula- ologists Ethan Bier and Val- approach such research in
could pass a specially en- nets are the main protec- tions — and the next chal- entino Gantz announced a low-income countries.
gineered malaria-blocking tion. lenge is how to speed that CRISPR-fueled gene drive The prestigious National
gene to about 99 percent process quickly enough to that worked in fruit flies. Academy of Sciences is
of their offspring. At the University of Cali- make a dent in malaria in For Monday’s study, the studying ethical issues sur-
The mutant mosquitoes, fornia-Irvine, molecular bi- any given region. San Diego research- rounding gene drive re-
kept in a secured lab, ologist Anthony James is Enter gene drives, a tech- ers teamed with James search, and the California
highlight the promise of developing what he calls nique that proponents say — packing the malaria- team says countries that
this technology along with “sustainable technologies” one day might be used to resistance genes with the struggle with mosquito-
questions about when and — rather than killing mos- wipe out invasive species CRISPR-based gene drive, borne diseases in particular
how it might be safe to try it quitoes, instead rendering like kudzu or cane toads, boosting chances of inher- should be involved. “Some-
in the wild. body sitting in the U.S. mak-
“This is a major advance ing up a list of rules has
because it shows that gene to appreciate that these
drive interventions will likely countries have their own
be effective in mosquito concerns,” James said.q
vectors of disease,” said
biologist Kevin Esvelt of Har-
vard’s Wyss Institute for Bio-
logically Inspired Engineer-
ing, a gene drive research-
er who wasn’t involved with
the newest study.
But because no one knows
how such rapid genetic
change might impact hab-
itats, Esvelt has urged the
public to weigh in. The Cali-
fornia study published on-
