Wolbachia Blocks Currently Circulating Zika Virus Isolates in Brazilian Aedes aegypti Mosquitoes

Abstract

The recent association of Zika virus with cases of microcephaly has sparked a global health crisis and highlighted the need for mechanisms to combat the Zika vector, Aedes aegypti mosquitoes. Wolbachia pipientis, a bacterial endosymbiont of insect, has recently garnered attention as a mechanism for arbovirus control. Here we report that Aedes aegypti harboring Wolbachia are highly resistant to infection with two currently circulating Zika virus isolates from the recent Brazilian epidemic. Wolbachia-harboring mosquitoes displayed lower viral prevalence and intensity and decreased disseminated infection and, critically, did not carry infectious virus in the saliva, suggesting that viral transmission was blocked. Our data indicate that the use of Wolbachia-harboring mosquitoes could represent an effective mechanism to reduce Zika virus transmission and should be included as part of Zika control strategies.

Graphical abstract

Figure 1

Wolbachia Infection Restricts ZIKV Infection in Ae. aegypti Mosquitoes (A–C) Wolbachia-infected (green circles) and -uninfected (black circles) mosquitoes were orally challenged with either (A) the BRPE or (B) the SPH ZIKV isolates. Wolbachia infection reduced both prevalence and intensity of ZIKV infection in mosquito heads/thoraces and abdomens at 7 and 14 dpi. Saliva was then collected for mosquitoes infected with the BRPE ZIKV isolate at 14 dpi infection (C), and we observed that saliva from Wolbachia-infected mosquitoes had a significantly lower rate of saliva infection and median viral load. (D) When these saliva samples were injected into ZIKV-uninfected Br mosquitoes, all of the Br saliva samples contained infectious virus, while no wMel_Br saliva produced a subsequent infection (columns: black, percentage infected; white, percentage uninfected; +, saliva contained infectious virus, −, saliva did not contain infectious virus). Absolute ZIKV copy numbers were quantified via qRT-PCR. In (A)–(C), each circle represents tissue or saliva from a single adult female (n = 20 per group). Red lines indicate the median ZIKV copies. ^∗∗∗, p < 0.0001; analysis by Mann-Whitney U test. In (D), each column represents mosquitoes injected with a single saliva sample.