Dengue is a potentially
deadly tropical illness that infects up to 100 million people
per year. Unfortunately, no effective vaccine exists for the disease
spread by the Aedes aegypti mosquito. But Malcolm Fraser
Jr., Notre Dame professor of biology, thinks a nifty bit of genetic
judo he invented may be able to turn the virus against itself.
Fraser's idea, which
recently earned a $2.5 million grant from the Grand Challenges
in Global Health initiative, is to use genetic engineering techniques
to produce a strain of Aedes aegypti mosquito immune
to the dengue virus and thus unable to transmit it. Basically
the idea is to load mosquito cells with an apoptosis-inducing
gene targeted specifically to splice onto the dengue virus. Apoptosis
is the scientific term for the natural process by which old or
damaged cells essentially commit suicide.
When the dengue virus
infects the mosquito cell, the suicide gene is activated and,
whammo, the cell dies. Since the virus needs the cell to replicate,
the virus dies when the cell dies. The insect then is immune and
incapable of passing the virus. "The beauty is you don't need
an abundance to suppress the virus. A low level should do the
trick," Fraser says.
Ultimately the plan is to release these genetically altered
mosquitos into endemic areas, which should then reduce the dengue-bearing
mosquito population. If the novel technique is successful with
dengue, Fraser believes it could work with other mosquito-borne
illnesses, such as yellow fever, Saint Louis encephalitis or West
Nile encephalitis.
(October 2005)
