Vector Competence of French Polynesian Aedes aegypti and Aedes polynesiensis for Zika Virus

Abstract

Background

In 2013–2014, French Polynesia experienced for the first time a Zika outbreak. Two Aedes mosquitoes may have contributed to Zika virus (ZIKV) transmission in French Polynesia: the worldwide distributed Ae. aegypti and the Polynesian islands-endemic Ae. polynesiensis mosquito.

Methodology/Principal Findings

To evaluate their vector competence for ZIKV, mosquitoes were infected per os at viral titers of 7 logs tissue culture infectious dose 50%. At several days post-infection (dpi), saliva was collected from each mosquito and inoculated onto C6/36 mosquito cells to check for the presence of ZIKV infectious particles. Legs and body of each mosquito were also collected and submitted separately to RNA extraction and ZIKV RT-PCR. In Ae. aegypti the infection rate was high as early as 6 dpi and the dissemination efficiency get substantial from 9 dpi while the both rates remained quite low in Ae. polynesiensis. The transmission efficiency was poor in Ae. aegypti until 14 dpi and no infectious saliva was found in Ae. polynesiensis at the time points studied.

Conclusions/Significance

In our experimental conditions, the late ability of the French Polynesian Ae. aegypti to transmit ZIKV added by the poor competence of Ae. polynesiensis for this virus suggest the possible contribution of another vector for the propagation of ZIKV during the outbreak, in particular in remote islands where Ae. polynesiensis is predominating.

Author Summary

From 2007, Zika virus has caused several outbreaks in the Pacific including French Polynesia. Aedes aegypti mosquito which is present in almost all Pacific Island Countries is reasonably expected to have been involved in the Zika outbreaks. In addition endemic Aedes mosquito species may have sustained Zika virus transmission in the less urbanized and most remote islands. In the present study we provide for the first time data about the vector competence of the endemic Ae. polynesiensis species for Zika virus. We found under experimental conditions a weak competence of Ae. polynesiensis for the virus. Furthermore we demonstrated a late ability of the French Polynesian population of Ae. aegypti to transmit Zika virus. These findings raise questions about the potential involvement of other vector(s) in Zika virus transmission in place or together with the Aedes mosquitoes. In a context where innovative vector control strategies are mostly focused on targeting the mosquito species considered as the main arbovirus vectors, the potential for others vector species to take the lead in transmitting such arboviruses should not be neglected.