Bacterium may help control spread of Zika: study

A bacterium being trialed to control the spread of Dengue fever has now been shown to prevent transmission of the Zika virus, researchers said Wednesday.

Aedes mosquitoes carrying the bacterium called Wolbachia, which was found inside the cells of 60 percent of all insect species, are drastically less able to transmit Zika, said researchers at Brazil's Oswaldo Cruz Foundation in a study published in the U.S. journal Cell Host & Microbe.

Wolbachia was first identified in 2005, and researchers successfully isolated the bacterium from fruit flies four years later.

In the Eliminate Dengue Program, Wolbachia is inserted into the eggs of Aedes mosquitoes, which have the ability to pass the bacterium to their offsprings. As a result, the Dengue virus replication in the mosquitoes was heavily reduced.

It seems the bacterium has the same effect on Zika transmission, the researchers said.

"The idea has been to release Aedes mosquitoes with Wolbachia in the field over a period of a few months, so they mate with Aedes mosquitoes without Wolbachia living in the place and, over time, replace the mosquito population," senior author Luciano Moreira of the Oswaldo Cruz Foundation explained in a press release.

"Zika and Dengue belong in the same family of viruses, so with the outbreak in Brazil, the logical idea was to test the mosquitoes carrying Wolbachia by challenging them with Zika virus and see what would happen," he said.

Moreira's team fed Brazilian field mosquitoes and Wolbachia-infected mosquitoes with human blood infected by two recent strains of the Zika virus that is circulating in Brazil.

After two weeks, the mosquitoes carrying Wolbachia had fewer viral particles in their bodies and saliva and the virus present in their saliva was not active. That meant after biting, the mosquito would not be able to transmit the Zika virus.

The reason for this drop in viral reproduction is unknown, but one theory is that because Wolbachia lives inside of the mosquito's cells, if the virus goes inside the cell to replicate, then there is an internal competition for resources, they said.

However, Moreira cautioned that the strategy is not 100 percent effective nor will it eliminate the virus.

"We know that there will not be only one solution for Zika -- we have to do this alongside different approaches, like vaccines or insecticides, besides the public measures to control Aedes breeding sites."

The researchers are currently discussing the Wolbachia approach with the Brazilian Ministry of Health, hoping to raise the resources and public support to test its effect on Zika in the field. Endit