Researchers at the University of Wisconsin-Madison have confirmed that a benign bacterium called Wolbachia pipientis can completely block transmission of Zika virus in Aedes aegypti, the mosquito species responsible for passing the virus to humans.
Thirty-nine countries and territories in the Americas have been affected by the Zika epidemic, and it is expected that at least 4 million people will be infected by the end of the year. Scientists believe the virus is responsible for a host of brain defects in developing fetuses, including microcephaly, and has contributed to an uptick in cases of a neurological disorder called Guillain-Barre syndrome. There are not yet any approved Zika virus vaccines or antiviral medications, and ongoing mosquito control strategies have not been adequate to contain the spread of the virus.
An important feature of Wolbachia is that it is self-sustainable, making it a very low-cost approach for controlling mosquito-borne viral diseases that are affecting many tropical countries around the world.
“In two of our initial study sites in Australia, approximately 90 percent of the mosquitoes continue to be infected with Wolbachia after initial release more than six years ago” says O’Neill.
Wolbachia can be found in up to 60 percent of insects around the world, including butterflies and bees. While not typically found in the Aedes aegypti mosquito, the species that also transmits dengue, chikungunya and yellow fever viruses, O’Neill discovered in the early 1990s that Wolbachia could be introduced to the mosquito in the lab and would prevent the mosquitoes from transmitting dengue virus.
Zika virus belongs to the same family as dengue virus and Aliota and Osorio, with co-authors Stephen Penaido at SVM and Ivan Dario Velez, at the Universidad de Antioquia in Medellin, Colombia, asked whether Wolbachia-harboring Aedes aegypti may also be effective against Zika virus.
In the study, the team infected mice with Zika virus originally isolated from a human patient and allowed mosquitoes from Medellin to feed on the mice either two or three days after they were infected. The mosquitoes were either harboring the same strain of the Wolbachia bacteria (called wMel) used in field studies or were Wolbachia-free and the mice had levels of virus in their blood similar to humans infected with Zika virus.
Until tomorrow: There is no substitute for hard work.
Dorothy Prats / [email protected]