Friday, March 19, 2010

Turning mosquitos into allies in disease control?

from GEN [Genetic Engineering & Biotechnology News] :

Japanese researchers have managed to engineer mosquitoes into “flying vaccinators” that could theoretically be used to deliver protein-based vaccines against diseases such as leishmaniasis and malaria through their bite. The team, from the Jichi Medical University in Japan, report on the development of a transgenic mosquito that can express foreign proteins in its saliva.

The authors stress that while the flying vaccinator concept could in theory be used to engineer blood-sucking insects as vaccine carriers against malaria, medical safety issues, concerns about informed consent, and other ethical considerations make it “unlikely that this concept will be developed as a public health measure”. However, they suggest that “salivary gland specific expression of relevant proteins is expected to be a powerful tool for the elucidation of saliva-malaria sporozoite interaction.”

Researchers have postulated for 10 years or so that genetically engineering mosquitoes could be a potential strategy against malaria, explains lead author and associate professor Shigeto Yoshida, Ph.D., and colleagues. “For the past decade it has been postulated that the salivary gland could be the way to gain biological control over this important infectious disease.” A major stumbling block, though, has been the inability to generate transgenic mosquito saliva.

See also PCT/JP2006/322417 ( WO/2007/052841 ):

Meanwhile, a mosquito punctures skin with its sharp oral needle which reaches the peripheral blood vessel when it sucks blood, and frequently repeats a puncture-in and -out behavior referred to as probing in order to find out the peripheral blood vessel. It is believed that the mosquito simultaneously secrets saliva containing a substance to facilitate vasodilation to make the detection of the blood vessel easy. Due to the above probing, the peripheral blood vessel is often damaged to become congested. Generally, when the blood vessel is injured, collagen in tissue under vascular endothelium is exposed, adenosine diphosphate (ADP) is released from broken cells, and coagulation factors are activated to form thrombin. Thrombin strongly activates the platelet to induce platelet adhesion, the platelet aggregation and granule release, and eventually forms a firm thrombus by blood coagulation with fibrin formation (hemostasis mechanism) . It has been known that the saliva of the mosquito contains the substance which inhibits such a hemostasis mechanism (see Non-patent literature D • A salivary gland protein in the mosquito, which has been studied in the most detail is apyrase. This enzyme is a platelet aggregation inhibiting substance which was identified in the saliva in Aedes aegypti for the first time. Apyrase inhibits the platelet aggregation resulting in decomposing from ADP released from damaged vascular endothelial cells, erythrocytes and adhered platelets to AMP (adenosine mono-phosphate) and to exhibit an anti-hemostatic action.

Separately, see

Intellectual Ventures works on mosquito laser


Blogger PDM said...

There is an interesting article at The (Skeptic's) Health Journal Club on how a former microbiologist is suing Pfizer claiming she was accidentally infected with a genetically modified virus used in research.

Perhaps we should be more concerned that some genetically modified pathogenic virus doesn't accidentally get picked up by a mosquito or other vector?

8:00 PM  

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