Malaria remains a substantial worldwide health problem. The Plasmodium parasite, the causative agent of malaria, develops into its human-infectious form in the salivary glands of female Anopheles mosquitoes. To perform research on transmission and development within the liver of the human host, researchers must dissect the salivary glands of hundreds of mosquitoes each week. There are malaria vaccine candidates that also rely on the frequent and speedy extraction of live parasites from mosquito salivary glands. The process of hand dissection is laborious for research and limits the ability to increase vaccine production to the scale needed for worldwide administration.
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We set out to reimagine and automate the way malaria parasites are extracted from mosquitoes. Over the course of a summer, we created and tested many different extraction mechanisms. In the end, we developed two devices: one that dissects mosquitoes in half and one that grinds the mosquito material to isolate the parasites. After years of testing and adjusting, we patented these robots in 2021 (#WO 2021/231918 A1). These devices are detailed below.
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Squito Splitter: Automatic Dissector
Standard mosquito dissection takes place under a microscope and consists of using two needles to pull off the mosquito's head, press down on its thorax, and tease out the six salivary glands. Careful attention is paid to avoid the midgut, located in the mosquito's abdomen, which contains parasites that are both less infectious and less immunogenic than salivary gland parasites. Hundreds of mosquitoes are typically dissected at one time and all the salivary glands are placed into one tube where they will be ground to release the parasites.
Parasites can only survive outside of their host for a limited time, so these dissections need to happen quickly. In fact, many projects are limited by the number of mosquitoes researchers can dissect in a two hour period. Performing dissections is a very specialized skill-- it can take months for researchers to be proficient in the accuracy and speed of their dissections. Dissections are such a daunting and variable task that some labs are discouraged from researching liver-stage malaria altogether.
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We set out to create an automatic dissector to speed up dissections and decrease the burden of entry into malaria research. After many iterations and experiments, we created the Squito Splitter which uses a rotary shear mechanism to separate the head & thorax of the mosquito from its abdomen. With the press of a button, researchers can pull a mosquito directly from its cage into the dissection mechanism and within seconds it's dissected. Our device takes days, rather than months, to master and allows researchers to dissect 5.6 times as many mosquitoes per hour than possible through manual dissection.
Squito Scrambler: Automatic Grinder
Malaria parasites are traditionally isolated from mosquito salivary glands by manually grinding mosquito material in an Eppendorf tube using a pestle. This process is tedious and highly variable between trials and between researchers. Our goal was to standardize grinding approaches and reduce researcher workload.
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The final design replicates a mortar and pestle. The user places the tube in the carriage and uses the control knob to choose the number of grinds. The stepper motor raises the carriage up to the pestle and the servo motor spins the pestle, after which the tube is lowered back down. The screen displays the number of grinds in real time.
In addition to dissecting out the salivary glands of mosquitoes, malaria researchers also perform dissections to remove the midguts of mosquitoes in order to check their level of malarial infection. The amount of parasites on the mosquito's midgut give researchers an idea of how many parasites will be in the salivary glands within a couple of days.
Hector: Midgut Dissector
Typically, midgut dissections are performed under a microscope, using two tweezers to pull the mosquito apart revealing the gooey midgut. These dissections are tedious and time-consuming.
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For one of my mechanical engineering classes, I designed a midgut-dissecting robot that has two arms to grab and pull apart mosquitoes on a glass slide. Since this was for a CAD class, the goal was to create a strong virtual design, not a physical, working device, so this project didn't move past the ideation phase.