Scientists engineer Zika-resistant mosquitoes

Australian and US scientists have engineered mosquitoes to be resistant to spreading the devastating Zika virus, which caused more than 4000 cases of serious birth defects in 2015 and is still a risk to millions of people. Their work has been published in the Proceedings of the National Academy of Science (PNAS).

Aedes aegypti mosquitoes normally pick up the Zika virus when they feed on the blood of an infected person, and can then spread the virus to the next person they feed on. While the virus itself is not currently present in Australia, Aedes aegypti is established in northern Queensland and the Torres Strait.

“People in 86 countries across Africa, the Americas, Asia and the Pacific are at risk of Zika,” said CSIRO Senior Research Scientist Dr Prasad Paradkar, a co-author on the new study. “Infection during pregnancy can cause life-threatening complications to a foetus or newborn baby, including birth defects such as microcephaly.

“With increased globalisation and international travel, the virus is capable of making it to Australian shores someday — so we’re collaborating with international partners to find innovative ways to reduce the risk both to Australians and to people around the world.”

The new study focused on a synthetic anti-Zika gene (anti-ZIKV), which was injected into mosquito embryos along with a red-eye gene to differentiate them from normal mosquitoes. The mosquitoes were engineered by the University of California San Diego and tested in the quarantined insectary at the Australian Animal Health Laboratory in Geelong, CSIRO’s national biocontainment facility designed to allow scientific research into the most dangerous infectious agents in the world.

Once the mosquitoes were adults, the researchers found that the anti-Zika gene prevented them from picking up the virus when they fed. They were therefore incapable of spreading the virus to anybody else.

“With further investigation, this mosquito could potentially one day be used to replace populations of wild Aedes aegypti, adding to the arsenal of control strategies against this mosquito to halt the virus’s spread around the world,” Dr Paradkar said.

Image caption: Zika-resistant mosquitoes were given a red-eye gene to distinguish them. Image courtesy of CSIRO.

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