Exciting news on the Zika virus front!

Researchers have now found that mosquitoes infected with Wolbachia pipientis are at a reduced risk to become infected with Zika virus.

The prevalence of Zika virus infection was significantly reduced in mosquitoes infected with Wolbachia bacteria. Determination of Zika virus infection in mosquitoes was accomplished by quantifying virus (plaque forming units/mL) in the head, abdomen and saliva of the mosquitoes. To determine whether transmission of the virus was affected, the saliva from Zika virus infected mosquitoes, that were co-infected with Wolbachia bacteria, was injected into the thorax of naive mosquitoes. The same was done for the saliva of mosquitoes in which Wolbachia bacteria were absent.

Result? None of the naive mosquitoes that were injected with saliva from  Wolbachia-coinfected mosquitoes became infected. In contrast when saliva samples of mosquitoes, unexposed to Wolbachia bacteria, were injected into naive animals, at least one mosquito became infected.

It seems that the reason for this inhibition of viral transmission is not due to an increase in the amount of Wolbachia RNA in the mosquitoes (a hypothesis that had been previously suggested), but that there are other ways by which this inhibition occurs.

Together these data suggest that co-infection of insects with Wolbachia bacteria may be a way to limit the transmission and damage produced by Zika virus.

Short intermezzo on Wolbachia bacteria

Wolbachia bacteria are present in about 40% of terrestrial insects and are used to control the spread of Dengue fever. Presence of this bacteria also reduces infection with Plasmodium and Chikugunya virus. In Brazil, the wMel strain is currently used exactly for this purpose of limiting Dengue fever.