Symbiotic microbes can have enormous impacts on their hosts’ health and evolution. Indeed, our own cells contain remnants of an ancient microbial symbiosis – the mitochondrion – which continues to provide us with metabolic capabilities essential to our physiology. Understanding the causes, mechanisms, and consequences of host-microbe interactions has emerged as a critical research objective at the interface of evolutionary biology, microbiology, ecology, and development. This project is based on the discovery that a bacterial symbiont changes the host cell in a particular way to protect it from viruses. In this proposed project, the researchers will investigate these changes in the host cell and identify how they alter host, bacterial symbiont, and invading virus. The investigators will use the fruit fly, Drosophila, the bacterium, Wolbachia that is a prominent member of the Drosophila microbiome, and the Sindbis virus which infects Drosophila, as a model system to study this phenomenon. The investigators will focus on RNA modifications to the fruit fly caused by the bacterium, which affect virus infection. Novel computational tools and wet lab protocols will be generated for dissemination to the broader community. Understanding the molecular underpinnings of symbiosis will help to (a) leverage that mechanism in the manipulation of agricultural and medically important microbiomes (e.g. probiotics and paratransgenesis), (b) reveal basic biology of broad relevance to life on the planet, and (c) better model the evolution of these interactions. Broader impacts include the generation of a project-based course at Indiana University focused on mosquito vectored viruses and outreach to the broader public through Indiana’s Environmental Resilience Institute.
Successful host-associated microbes sculpt host cell biology in ways that are useful to them. Often, these changes in host biology alter the ability of other microbes to colonize, protecting the host niche for the first microbe. For example, colonization of insects with Wolbachia endosymbionts can preclude infection by viruses. This fact has led to the deployment of Wolbachia-infected mosquitos across the globe to limit the transmission of vectored diseases. This project is based on RNA modifications induced by Wolbachia that directly alter Drosophila cell biology and affect the ability of viruses to colonize. Wolbachia upregulates a host methyltransferase to limit virus replication and preliminary data suggest that the virus genome itself is modified in a Wolbachia infected cell, altering mRNA stability. These data lead to the following question:“How does a microbial symbiont alter the epitranscriptomic landscape of host cells?†This proposed project will identify modifications in both host DNA and RNA induced by Wolbachia and virus using direct sequencing approaches (PacBio and ONT), benchmarked by more established methods (bisulfite sequencing and mass spectrometry). In the process, wet lab protocols for generation of appropriate controls for Nanopore sequencing and bioinformatic pipelines for the analyses of epitranscriptomic datasets from Nanopore sequencing will be developed. All resources will be made broadly available and open access. Finally, the importance of these changes will be identified using molecular virology and Drosophila genetics. In sum, this work will identify how epitranscriptomic modifications link genotype to phenotype in this important symbiotic system.
This project is funded by the Understanding the Rules of Life: Microbiome Theory and Mechanisms Program, administered as part of NSF's Ten Big Ideas through the Division of Emerging Frontiers in the Directorate for Biological Sciences.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
