Scientists in Australia are looking at some pretty creative ways to tackle the Zika virus, which continues to pose a risk to millions across Africa, Asia and parts of the Americas. Following a trial last year where researchers were able to decimate disease-spreading mosquitos in the country's north, scientists have now demonstrated an engineering technique that renders the biggest transmitter of the virus largely immune to it, raising hopes of a new way to control the spread of Zika and other mosquito-borne diseases.
The trials conducted last year were the result of a collaboration between Australia's James Cook University, scientists from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and US mosquito-rearing startup Verily. The scientists set out to reduce the population of the Aedes aegypti mosquito in northern Queensland by infecting them with a naturally occurring bacterium, and were able to do so with great success.
The Aedes aegypti mosquito is the not only the biggest transmitter of the Zika virus, it is also the number one disease vector for dengue fever, a carrier of yellow fever and of course the big one, malaria. For this reason, scientists have been attempting to use genetic engineering to limit the damage for some time, though never in this way specifically.
"There have been a few other studies where researchers have modified mosquitoes, with some success in the lab in reducing virus transmission," Dr Prasad Paradkar, a senior research scientist at CSIRO, explains to New Atlas. "This particular research is unprecedented in engineering a mosquito which completely blocks the virus and could be easily adapted to work for other viruses such as dengue."
An Aedes aegypti mosquito spreads the Zika virus, with great effect, by feasting on the blood of an infected person and then biting another. Paradkar and his colleagues may now have a means of intervention, engineering a version of the mosquito that has trouble contracting the virus in the first place.
The scientists did this by injecting a synthetic anti-Zika gene into the mosquitoes during the embryo stage, along with another gene to give them red eyes so they could be differentiated from the others. Interestingly, this somewhat spooky technique is commonly used in genetic engineering research as a means of identification, including an effort to block the spread of mosquito-borne malaria back in 2015.
The new testing was carried out within a quarantined insectary at the CSIRO's biocontainment facility, where the researchers found the addition of the anti-Zika gene largely prevented the modified mosquitoes from picking up the virus, with significantly lower rates of infection and transmission.
These results raise the prospect of one day feeding these modified mosquitoes into the wild to start crowding out bugs capable of transmitting infections, but Paradkar says there is still plenty to be done before that happens.
"This would require breeding a large number of these mosquitoes in a lab and releasing them in affected regions to stop transmission," he tells us. "However, we're not at that stage yet. We need to conduct further experiments and risk analysis around the ecological safety of this work, and there would need to be well-informed public discussion and community engagement around this possible avenue, alongside with the necessary regulatory approvals."
Though the team faces some obstacles in getting the technology into the field, there is a precedent for pilots involving genetically engineered mosquitoes and the Zika virus, with the US Food and Drug Administration approving a trial to that effect in 2016. Though this latest work was carried out with a view to tackling Zika directly, Paradkar and the team are already turning their attention to other mosquito-borne diseases as well.
"We are planning to test whether we can use a similar strategy to block mosquitoes from transmitting other viruses," he says. "We will initially focus on dengue virus, which infects more than 300 million people around the world every year."
The team's research was published in the journal PNAS.
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