Anna-Bella Failloux is the leader of ZIKAlliance WP6 and Principal Investigator.
What work do you do on Zika – and specifically within ZIKAlliance?
My main field of expertise is the transmission of arboviruses by mosquitoes. In ZIKAlliance, I am leader of WP6 on Vectors and Control. This WP gathers 18 teams for developing 4 tasks (Identification of ZIKV vectors, Vector competence, Interactions between ZIKV and other flaviviruses, Mosquito Control using conventional and innovative tools).
How is WP6 investigating vector transmission of Zika virus?
Task 6.1 aims to puzzle out the complexity of transmission cycles (wild and epidemic) leading to Zika emergence. Our strategy will be based on: (1) the identification of vectors involved in ZIKV transmission, (2) the assessment of vector competence of different mosquito (wild and domestic) populations, (3) the understanding of interactions between ZIKV and other flaviviruses with potential consequences in selecting new epidemic variants of ZIKV, and (4) the appraisal of insecticide resistance and design of alternative strategies for the control of disease transmission.
As of today, what can be said about the role of co‐infections in mosquitoes on the selection of epidemic variants of ZIKV?
Once mosquito females are infected, she remains infected for life. Then, if the infected female takes a second blood-meal on a viremic patient presenting a different virus, she can become co-infected. Using experimental infections of mosquitoes, we have reproduced these co-infections and we found that the amount of ZIKV released in mosquito saliva can change depending on whether ZIKV is with DENV or CHIKV. The analysis of diversity of viral populations is on-going.
What is the current situation of insecticide resistance with regards to mosquito populations in the Zika affected countries? On what kind of tools is your group working to control the spread of Zika?
Insecticide control strategies against Zika are designed to combat mainly Aedes aegypti and Aedes albopictus which can share the same breeding sites, usually man-made containers. Mosquito populations have become resistant to insecticides in urban environments. The regions devastated by Zika are not an exception. Partners of the task 6.4 (IBMC Strasbourg, PIMIT La Réunion, IRD La Réunion, WU Netherlands) are developing alternative tools more sustainable and environmentally friendly, such as the use of molecules to counteract the mosquito antioxidant defense, releases of sterile males and Wolbachia-infected mosquitoes. We are also developing new traps that attract and kill host-seeking mosquitoes.
What are the main mosquito species involved in urban and rural transmissions? In what aspects does transmission differ between them – if at all?
Aedes aegypti and Aedes albopictus are the main vectors in cities; they are human-biting mosquitoes and breed in artificial sites such as vase, barrels..They intervene as Zika vectors in an epidemic cycle. On the other hand, the enzootic/wild cycle has been primarily described in Africa where ZIKV circulates between non-human primates and zoophilic mosquitoes such as: Ae. dalzieli, Ae. fowleri, Ae. furcifer, Ae. luteocephalus, Ae. metallicus, Ae. minutus, Ae. neoafricanus, Ae. tarsalis, Ae. vitattus, Ae. africanus, Ae. flavicollis, Ae. furcifer, Ae. graham, Ae. opok, Ae. taeniarostris, Ae. tarsalis, Ae. vitattus…The trophic preference of these last mosquitoes towards animals limit the transmission of ZIKV to humans.
Why did you want to participate in ZIKAlliance?
Zika is a vector-borne disease. Understanding Zika emergence without addressing the transmission by the vector would make very little sense. ZIKAlliance has brought together the greatest number of entomologists tackling all aspects of the vectorial transmission including the vector control.
What do you consider the biggest challenge(s) to participating in this project?
My biggest challenge is coordination. We are 18 partners scattered across 5 continents: as an example, the most distant partner is based in New Caledonia, which is 17,000 km from Europe!
So far, what would you say is the best thing about being part of this project?
The collaborative nature of the project that reflects the complexity of Zika, with so many disciplines involved. Discussing with epidemiologists, modelers, immunologists, clinicians, virologists and many others is a great opportunity and a real pleasure.
Where do you think we are in understanding of Zika transmission in five years’ time?
I think that we have delivered one third of the project so far. We know now that Aedes aegypti is the main vector; its vector competence will depend on the origin of the mosquito population and the genotype of ZIKV. We can suggest that mosquito control should mainly target this species. Other Aedes mosquitoes can intervene secondarily. In addition, the night-biting mosquito Culex quinquefasciatus can be involved as Zika vector.
And what do we need to do to get there?
We are on the right track and only need time to fulfill our objectives.