I hate mosquitoes. I should know. I worked in a mosquito lab for over a year and among other stuff, I was also in charge of maintaining the insectory. I worked with a PhD scholar, Vinay Shetty, in Bangalore University. My project was – uhmm how do I put this tactfully – silly, the mosquitoes– annoying. But the experience was, well, surprisingly rewarding. And, I ended up learning more about mosquitoes than I would have liked.
Truth be said, as well as I would gladly welcome the idea of a mosquito-free world, it isn’t practically feasible. Period. No, the issue isn’t the plausible ecological imbalance as you would imagine, but the mere impossibility of getting rid of the pesky critters, altogether, from across the globe. Given that mosquito eradication is ruled out, disease control becomes the next best alternative. And, while numerous research labs, world over, are working on this, one group from the University of California have taken one step closer to this realizing this vision – and, with a very intriguing approach.
In an inter-department collaborative effort, Professors Anthony A James and Ethan Brier and their teams have approached the problem at hand using the concept of immunization. The researchers introduced genes into the disease-causing mosquito – Anopheles Stephensi – that will trigger the production of antibodies in the mosquito body against the malarial parasite, Plasmodium Falciparum.
Antibodies are molecules produced by living organisms to fight diseases. Every time you are infected with a bug, your body produces antibodies against it that eventually wipes out the entire bug population from the system. Vaccinations, in fact, work by priming your body to produce antibodies against specific pathogens. What Prof. James and Prof. Bier have achieved is essentially is an anti-malarial vaccination for mosquitoes. The only distinction is that, in this case, the vaccination will be carried across generations. In other words, mosquitoes with the new-gene inserts, and the babies they produce, will not be able to host the malarial pathogen any more, thus leading to disease elimination.
The technology would require the release of the genetically engineered (GE) mosquitoes into the environment. These GE mosquitoes from the lab would then mate with the mosquitoes in the wild and produce mosquito babies with the new gene insert. This isn’t the first time that such GE-driven mosquito pathogen eradication has been envisioned. Field trials of similar GE mosquitoes that have been released to the field have made it to global headlines. You would then wonder – what makes this particular study blog-worthy?
Let me explain. Mosquitoes released into the field need to pass on their disease-curbing genes to their progeny. Often times (especially in the wild), the percentage of mosquito progeny that pick up the engineered copy of the gene isn’t very encouraging. You must know, that babies get one set of genes from their mom, the other from their dad. This baby (with possibly one copy of the engineered gene) would then mature into an adult, and the chances that it passes on the GE gene to the next generation is only 50%. So, with each generation, the number of mosquitoes – possessing the engineered gene that can prevent the disease – drops further and further. But, in the case of the mosquitoes produced by the James–Bier team, this was not so.
The scientists used the CRISPR – Cas9 gene editing system, which happens to be the most precise method of genetic manipulation available today. However, they modified this technology such that the engineered antibody gene is incorporated into roughly 99.5% of the progeny derived from mating the engineered flies with wild ones. How did they do this?
The modification involved the use of an adapted version of the MCR (mutagenic chain reaction) technology that was previously developed in Prof. Bier’s lab. This involved tweaking the CRISPR – Cas9 gene editing system to ensure that both copies of the chromosomes of the GE mosquitoes would contain the new anti-malarial antibody genes. Of course, as far as research studies so, this work still has a long way to go before it hits the field, as acknowledged by the authors themselves. Although, you must admit, the results of this study do provide for an alluring vision of a malaria-free world.