Breadth and mechanism of Wolbachia-based inhibition of fungal infection in Drosophila - Project Summary:
Host-symbiont interactions represent an enormous variety of relationships with an extraordinary array of
resulting phenotypes. Microbial symbionts of arthropods have a particularly wide range of symbiotic interactions
with their hosts. One exceptional case is that of Wolbachia bacterial symbionts that are found in almost half of
all arthropod species. These microbes are genetically and phenotypically highly diverse, and various strains
have abilities ranging from manipulation of host reproduction to provision of essential host nutrients. One unique
and highly consequential feature of some Wolbachia strains is the ability to inhibit transmission of viruses
including Zika and dengue from arthropods to humans. Several global initiatives have taken advantage of this
ability to use Wolbachia to successfully fight arthropod-borne disease. However, the mechanism of pathogen-
blocking is unclear, as is the breadth of the phenotype in terms of affected pathogens. This limits the ability to
predict the success of current vector control field trials and to identify and develop new applications of the
phenotype. Preliminary data shows that Wolbachia pathogen inhibition extends to diverse fungi as well, since
Wolbachia-positive Drosophila melanogaster flies live longer after systemic infection with a variety of fungal
pathogens. It also suggests host immune priming may underlie the mechanism. This proposal outlines a set of
organismal, genetic, and molecular approaches to build a comprehensive profile of Wolbachia-fungal interactions
in Dipteran hosts. This proposal will primarily use the elite genetic model, Drosophila melanogaster, with the
wMel Wolbachia strain, the same strain that is utilized in antiviral initiatives. Aim 1 will functionally assess the
role of host immune priming in the mechanism, focusing on specific genes of interest in the Toll and JAK/STAT
pathways, using genetic and transcriptomic approaches. In Aim 2, trans-infections, feeding assays, and
metabolomics will be used to assess the role of Wolbachia factors, nutritional competition, and fungal metabolite
inhibition in the phenotype. Aim 3 will test translational potential by assessing fungal protection in Aedes
mosquitoes, inhibition of inter-individual fungal transmission, and the population benefits of fungal protection in
cage populations. This approach leverages many powerful approaches and techniques to provide an extensive
characterization of Wolbachia-fungal interactions. Doing so will provide insight into Wolbachia pathogen blocking
mechanisms, the basic biology of interkingdom microbial interactions, and potentially inform and bolster vector
control initiatives. With guidance from Advisory Committee members Drs. Ackley, Oakley, and Michel and
sponsor Dr. Unckless at the University of Kansas, this proposal encompasses a comprehensive plan with all of
the training needed for Dr. Perlmutter to achieve the career goal of becoming an independent investigator
studying the genetics and mechanisms of host-symbiont interactions with a main focus on arthropods.
