Science 3 min read

Mosquitoes' Salivary Gland "Bottleneck" Could be Key to Ending Malaria

Image courtesy of Shutterstuck

Image courtesy of Shutterstuck

Scientists at Johns Hopkins Medicine believe that a salivary gland “bottleneck” in mosquitoes could be the key to stopping malaria permanently.

Mosquitoes carry thousands of Malaria-causing parasites in their tiny body. Yet, when slurping blood from their victims, the insects can only manage to transmit a small fraction of the parasite.

How this is possible is a big mystery.

While past studies revealed that some roadblocks stop the parasites in the insects’ salivary glands, none of them were able to identify how it works.

In a statement, lead author of the study and postdoctoral researcher at the Johns Hopkins University School of Medicine, Michael Wells, Ph.D., said:

“Even though thousands of parasites invade the salivary gland, less than a 10th of them are transmitted during a mosquito bite. So, we knew that the salivary gland is blocking the parasites from getting out, but we didn’t know exactly how.”

In their article in the journal mBio, the researchers described how they found the bottleneck.

Finding the Bottleneck in the Mosquitoes’ Salivary Gland

The salivary gland of an Anopheles mosquito is made up of three lobes of saliva-producing cells in a protective sheet called the basement. Then, a long duct extends from the lobes straight into the insect’s mouth.

That means a parasite must pass through the basement membrane and a layer of salivary cells. It then has to swim across the secretory cavity before reaching the salivary duct.

For their study, the researchers first fed malaria parasite-rich rodent blood to a scourge of Anopheles mosquitoes. Then they dissected the salivary glands mosquitoes and also used a high-powered microscope to identify the parasites’ location.

While a few of the parasites were in the salivary ducts, most were either in the secretory cavity or the basement membrane.

Wells noted:

“The parasites seem to have no trouble getting into the salivary glands. So, this told us that the obstruction happens later, when parasites are trying to get to the salivary duct.”

Read More: Researchers Explore Why Mosquitoes Choose Humans

Using the microscope, the researchers zoomed in on the cell layers in each lobe of the salivary gland. That’s when they noted the sturdy fibrous wall around the salivary glands which prevented the parasite from leaving the secretory cavity.

A few of the parasites were able to burrow through the chitin wall to reach the salivary duct. However, the opening was too narrow for most of the parasites to pass.

According to Wells, mosquitoes release the lucky few that made it through the membrane during a bite. Based on this logic, we can prevent mosquito infections by fortifying the chitin wall.

A professor of cell biology at the Johns Hopkins University School of Medicine, Deborah Andrew, M.S., Ph.D., said:

“Our findings add substantial detail to the role of mosquito salivary glands as the gateway organs for diseases spread by these insects. By enhancing transmission barriers that naturally exist in mosquitoes, we potentially can block the spread of malaria and other deadly mosquito-borne diseases, like Zika fever.”

Read More: A New Study Reveals How the Mosquitoes Fights Off Malaria

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Sumbo Bello

Sumbo Bello is a creative writer who enjoys creating data-driven content for news sites. In his spare time, he plays basketball and listens to Coldplay.

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