Mosquitoes programmed to vaccinate.

Mosquitoes programmed to vaccinate

A team of Japanese researchers has managed to genetically modify a mosquito to broadcast a vaccine when he stings a mouse. An experience that raises many practical and ethical questions.

The idea would have something to dream about: instead of carrying serious diseases (malaria, dengue fever, yellow fever), mosquitoes, genetically modified by humans, transmit to individuals that they bite the vaccine against this same disease. And each new sting, far from being dangerous, would strengthen the immune defense of the "stung" person. An "inexpensive and painless" method, summarizes Dr. Yoshida, who conducted the scientific study published in the journal Insect Molecular Biology.

This Japanese scientist from the Jichi Medical University has managed to concretize in his laboratory a theory cherished, according to him, for a decade by researchers. For this, he introduced a gene in a mosquito to produce in its saliva the SP15 molecule to immunize against a serious tropical disease, leishmaniasis. Particularly virulent in North Africa, the Middle East and the Sahel, leishmaniasis, also present on a smaller scale in the south of France, affects 12 million people worldwide and can be fatal or cause serious injury. skin.

The researchers then put these genetically modified mosquitoes in contact with mice. Repeatedly stung by the insect that fed on their blood, they developed antibodies against leishmaniasis, like a conventional vaccine, which, by introducing the infectious agent at a very low dose body, teaches him to organize his immune defense. The mosquito, through its saliva, had indeed played its role of "flying vaccinator".

In the lab only

"This is an original idea, says Dr. Jean Beytout, head of infectious diseases at Clermont-Ferrand University Hospital. Until now, attempts have been made to make genetic selection on mosquito vectors of disease, in order to reduce their number or their danger.

The prowess of the Japanese team, however, remains experimental and is not intended to be scaled up. Dr. Yoshida's team itself recognizes several obstacles to this. Not only does it seem impossible to measure the molecule inoculated with individuals by insects, but nothing also ensures that the same insect does not transmit, at the same time, another disease, such as malaria or yellow fever. In addition, there are ethical considerations, since we would be unable to ensure that the person agrees to be vaccinated.

"In the end, this study finds its interest especially in the tracks it opens for research on malaria, summarizes Dr. Beytout. It highlights the essential role of mosquito saliva at least, some of its components to promote the penetration of the immunizing molecule in the blood.

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