# 4971
Global Spread of Dengue
Late last month I reported (see Malaysia: `Terminator’ Mosquito Field Test On Hold) that plans to release genetically modified (GM) mosquitoes were temporarily delayed due to concerns voiced by critics and activists.
This so-called `Terminator’ mosquito has been bio-engineered to carry a lethal gene that it will pass on to its progeny that will cause them to die in the larval stage.
Oxitec has a short FAQ page on their technology, which you can access here.
The hope is that a release of several thousand of these GM mosquitoes could help reduce the burden of Dengue in hard-hit Malaysia, and provide a limited field test of the technology as well.
Critics, however, say that any environmental contamination by tetracycline – a common antibiotic – would thwart the process. They also worry about the potential for unanticipated consequences from the release.
Last year, another planned release of GM mosquitoes on Pulau Ketam island off the port city of Port Klang was aborted because of vocal opposition from the residents.
Today, Malaysia’s health minister Liow Tiong Lai said – barring any unforeseen circumstances - that the planned release of these GM mosquitoes was back on, and expected before the end of the year.
Malaysia to carry out landmark GM mosquito trial
Posted: 10 October 2010 1620 hrs
With the rising global impact of Dengue - and other mosquito borne illnesses like malaria, Chikungunya, and various forms of encephalitis - the notion of bio-engineering a solution to the problem has garnered a fair amount of attention.
A different bio-solution to the Dengue problem will be attempted in Australia and Vietnam next year when scientists plan to release mosquitoes infected with a fruit-fly bacterium called Wolbachia that halves their lifespan and makes them less capable of carrying the Dengue virus.
Anti-dengue mosquitoes to hit Australia and Vietnam
08 October 2010
The greatest mosquito borne threat is malaria, and once again, scientists are working on bio-solutions.
Earlier this summer researchers announced that they had successfully switched on a gene that produced a `malaria-destroying response’ in at least one species of mosquito.
The details appeared in the PloS Pathogens study.
Activation of Akt Signaling Reduces the Prevalence and Intensity of Malaria Parasite Infection and Lifespan in Anopheles stephensi Mosquitoes
Corby-Harris V, Drexler A, Watkins de Jong L, Antonova Y, Pakpour N, et al. (2010) Activation of Akt Signaling Reduces the Prevalence and Intensity of Malaria Parasite Infection and Lifespan in Anopheles stephensi Mosquitoes. PLoS Pathog 6(7): e1001003. doi:10.1371/journal.ppat.1001003
In an excerpt from the author’s summary, they write:
In this study we demonstrate that tissue-specific overexpression of a single activated protein kinase that is essential to insulin signaling in the mosquito can dramatically reduce parasite development. This kinase – Akt – has been described as a critical cell signaling node that regulates a range of physiological processes.
In addition to the impact on parasite development, increased Akt signaling also reduced the average mosquito lifespan relative to controls, thereby limiting the window of opportunity for successful parasite transmission. Thus, we demonstrate that genetic manipulation of one key signaling protein directly reduces parasite development in the insect vector as well as the duration of mosquito infectivity.
Essentially, by inserting a special version of the Akt gene into the eggs of Anopheles stephensi mosquito, its ability to carry the Plasmodium parasite is greatly diminished and its lifespan significantly reduced.
One of the authors, Professor Michael Riehle at the University of Arizona, in an interview carried by Discovery News, stated that while extremely promising a release of these GM mosquitoes was `at least a decade away’.
While developing an engineered mosquito in the laboratory is an impressive feat, getting it to thrive and compete successfully in the wild may prove to be a much bigger challenge.
Another challenge will be getting the public to accept the idea of releasing GM mosquitoes.
For many people, simply the words `genetically modified’ are enough to raise concerns.
As these diseases encroach on North America, Europe, and other developed areas of the world we may find that the public acceptance of a bio-engineering solution will grow.
Assuming, of course, that these early field tests come off without a major hitch.
Given that there are hundreds of millions of mosquito-borne illnesses each year around the world – and millions of deaths – the stakes here are enormous.
Admittedly these early field tests may not make a big dent in those numbers, but some early successes could help pave the way to bigger gains down the road.
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