Towards the Use of Novel High Density Anopheles-Specific Wolbachia Strains for Anopheles Vector Control.

T1 - Basic Research T2 - Human/Clinical Research

In its most recent report, the World Health Organisation estimated 247 million cases of malaria, with 619,000 associated deaths worldwide. The recently reported reduction in efficacy of established vector control methods is of particular concern given the vast contribution they have made to the reduction in malaria burden worldwide. The introduction of the Asian Malaria Mosquito, Anopheles stephensi, a highly adaptable urban vector into sub-Saharan Africa presents an additional barrier to malaria elimination. Wolbachia-based interventions have proven highly effective when targeting Aedes mosquitoes, the prominent vectors of arboviruses. In a recently published cluster randomised control trial, the release of Wolbachia infected mosquitoes was associated with an 77% reduction in dengue incidence and an 86% reduction in dengue hospitalisations demonstrating not only the viability of a Wolbachia based vector control strategy but also the translational nature of Wolbachia research. Given that malaria is responsible for the vast majority of mosquito-borne disease related morbidity and mortality, it is unsurprising that there has been great interest in developing a Wolbachia based malaria intervention. The main barrier to a viable intervention has been the difficulty of producing a Wolbachia infected Anopheles mosquito, with the only stable transinfection generated, known to carry a heavy fitness cost. Until recently, wild populations of Anopheles mosquitoes were believed to be free of Wolbachia infections, despite many species of mosquito and 50% of all insect species thought to be infected. The recent discovery of the first two confirmed Anopheles-specific Wolbachia strains, wAnD and wAnM in two vectors An. demeilloni and An. moucheti respectively, has reinvigorated research, with the expectation that Anopheles mosquito Wolbachia transinfections using Anopheles-specific strains will prove more successful. The proposed project exists in the juncture between the discovery of these strains, and their use as an intervention. I will investigate the unique relationship between Anopheles mosquitoes and Wolbachia, aiming to determine some of the factors that influence the susceptibility of Anopheles to Wolbachia while taking the first steps towards the use of these strains for malaria control.

Aim 1
Identifying and mitigating factors limiting Wolbachia infection in-vitro
1.1 Develop the framework for a mechanistic model to better understand factors limiting the success of in-vitro Wolbachia infection.
1.2 Use high throughput testing within the developed framework to identify the factors that limit Wolbachia infection of cells.
1.3 Compare the ability of wAnD, wNo and wAlbB to infect Aedes and Anopheles cells
1.4 Develop an optimised protocol for infecting cell lines with Wolbachia
1.5 Generate cell lines stable infected with Wolbachia strains of interest.

Aim 2
In-vivo analysis of Host-Wolbachia Interactions During Embryonic Development
2.1 Characterising Wolbachia tropism during early embryonic development
2.2 Characterising Wolbachia tropism following embryonic microinjection.
2.3 Compare the host response upon embryonic microinjection with Wolbachia.
2.4 Compare host response in mosquitoes upon microinjection of Wolbachia from different sources.

Aim 3
Characterise Wolbachia host interaction in naturally infected populations of Anopheles
3.1 Characterise Wolbachia tropism in wild-caught An. moucheti
3.2 Assess host response in offspring of naturally infected An. moucheti mothers