Researchers' Malaria-Resistant Mosquitoes Thrive in
Lab
By Tim Parsons School of Public Health
Researchers at the Johns
Hopkins Malaria Research Institute have determined that
genetically engineered malaria-resistant mosquitoes fare
better than their natural counterparts when fed
malaria-infected blood. The results of their study,
published March 19 in the online edition of the
Proceedings of the National Academy of Sciences,
indicated that genetically engineered (transgenic)
mosquitoes lived longer and produced more eggs compared to
wild-type mosquitoes.
The findings, the researchers said, are an important
next step toward developing malaria control strategies
using genetic modification of mosquitoes. Theoretically,
mosquitoes resistant to malaria could be introduced into
nature to replace malaria-carrying mosquitoes. To be
successful, transgenic mosquitoes would need to produce
more offspring and show lower mortality in order to replace
wild-type mosquitoes. However, the researchers stressed
that any potential malaria control strategy using
transgenic mosquitoes would still require years of
study.
For this study, Marcelo Jacobs-Lorena, a professor in
the Bloomberg School of Public Health's
W.
Harry Feinstone Department of Molecular Microbiology and
Immunology, and his JHMRI colleagues combined equal
numbers of transgenic and wild-type mosquitoes and let them
feed on malaria-infected mice. After nine generations, the
transgenic mosquito population grew to 70 percent vs. 50
percent at the beginning of the experiment. According to
the researchers, this fitness advantage arose because the
transgenic mosquitoes had a higher survival rate and laid
more eggs. They said any potential negative effects of a
transgene may be overcome by the advantage conferred by not
being infected with malaria parasites.
When fed noninfected blood, the transgenic mosquitoes
showed no advantage over the wild-type mosquitoes. For
malaria control, transgenic mosquitoes would need to
overtake wild-type mosquitoes even when not exposed to
malaria parasites, because only a small percentage of
mosquitoes are exposed to malaria in the field.
The study, supported by funding from the National
Institutes of Health and the Johns Hopkins Malaria Research
Institute, was written by Mauro T. Marrelli, Chaoyang Li,
Jason L. Rasgon and Jacobs-Lorena. Rasgon is also with the
Bloomberg School's W. Harry Feinstone Department of
Molecular Microbiology and Immunology. Marrelli is
currently with the Universidade de Sao Paulo in Brazil, and
Li is with Case Western Reserve University, Cleveland.
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