Protein In Mosquitos’ Saliva Impacts Feeding

Scientists in Japan and Portugal have shown that a protein called AAPP, found in mosquito saliva, affects the insects’ feeding behavior, with implications for mosquito fitness.

AsianScientist (May 30, 2019) – An international team of scientists has found that a protein in the saliva of mosquitos influences the insects’ feeding behavior. They published their findings in the journal Scientific Reports.

Biting insects use a range of tools when sucking blood from hosts so as to maximize their chances of a good meal. In the case of mosquitos, only the females feed on blood, which provides a high level of nutrients for egg production.

A salivary protein in the saliva of mosquitos, called AAPP, is known to inhibit clot formation after biting by preventing platelets from binding to collagen. In this study, researchers led by Mr. Ashekul Islam at Kanazawa University, Japan, investigated how AAPP may regulate the feeding behavior of mosquitos.

The team first modified a transgene expression system to specifically express an artificial antibody against AAPP in the salivary glands of mosquitos. They confirmed that the antibody prevented AAPP from binding to collagen in transgenic mosquitos, thereby promoting blood clotting.

“We studied the behavior of transgenic mosquitos expressing the anti-AAPP antibody compared with wild-type controls when feeding on mouse hosts,” Islam said. “Transgenic mosquitos took significantly longer to establish feeding after inserting their mouth parts into the host and had significantly prolonged prediuresis times.”

Prediuresis is the process by which blood-sucking insects excrete drops of fluid to concentrate ingested blood protein within a small volume that fits in their midgut. However, long probing and prediuresis times come at a risk because they alert hosts to the action of biting, which can be detrimental to the insect. Transgenic mosquitos also performed worse than their wild-type counterparts in terms of the volume of blood ingested, which directly reduced their egg production.

“Despite these clear behavioral changes, there was no difference in the number of malarial parasite oocysts developing within wild-type or transgenic mosquitos,” said corresponding author Assistant Professor Shigeto Yoshida of Kanazawa University. “This shows that the size of the blood meal alone did not affect parasite development in our laboratory model.”

In the real world, however, the authors believe that the high fitness demands of malarial parasite burden would compromise the fitness of transgenic mosquitos with inactivated AAPP.

The article can be found at: Islam et al. (2019) Anopheline Antiplatelet Protein From Mosquito Saliva Regulates Blood Feeding Behavior.


Source: Kanazawa University; Photo: Pixabay.
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