Host-Microbe Symbioses & Disease
My research spans the fields of disease ecology and microbiology to investigate the interplay between hosts, symbionts, and parasites throughout all stages of life. I aim to define and develop a better understanding of complex interactions within host-symbiont-parasite systems and determine how ecological and evolutionary factors influence these interactions to alter disease states and infection outcomes. By integrating evolutionary and ecological approaches with in vitro and in vivo assays I'm able to inform the broader field of host-microbe symbioses while ascertaining how ecological drivers influence pathogen invasion and interactions with the host gut microbiome across diverse taxa.
01
Disease Triangle of a Honey Bee Host-Symbiont-Parasite System
Influence of thermal ecology on host-microbe symbioses
Honey bees present a perfect model system to study the complex interactions within host-symbiont-parasite systems. In addition to having a well-defined and consistent core set of bacterial symbionts, these essential pollinators are readily available and easy to rear in laboratory environments. As ‘facultative endotherms’, honey bees are known to thermoregulate their colonies, keeping the center of their brood clusters at about 34°C to 37°C.
This temperature range is exceptionally warm for most ectothermic arthropods and presents the question of how honey bee-associated microbes respond to their hosts’ facultatively endothermic lifestyle, and how those responses affect interspecific interactions within the bee gut.
​
My work in this system aims to answer several key questions:
-
How do co-occurring symbiont communities and their interactions change in response to temperature variation? Parasite challenge? Host stress?
-
How do hosts respond to thermal stress and symbiont community disruption?
02
Ecological drivers of large scale infection dynamics
Another aspect of my research strives to understand how ecological factors influence large scale infection dynamics of trypanosomatid parasites. Monoxenous trypanosomatids are ubiquitous one-host parasites that infect humans, animals, and plants across the globe, but the factors that influence their distribution often remain unclear.
​
Examining ecological relationships on a national, and eventually global, scale via experimental manipulation is often limited by the constraints of the laboratory and therefore must rely upon collaborative work spanning across continents or meta-analyses from previously gathered or published work, but one alternative to these limitations is to conduct widespread geographic surveys.
​
By surveying geographically diverse beekeeping operations for two ubiquitous trypanosomatids, Crithidia mellificae and Lotmaria passim, my work aims to assess the ecological drivers of the fine-scale spatiotemporal distribution of these parasites by ascertaining:
-
How does climate (i.e. temperature, precipitation, etc.) influence the prevalence of trypanosomatid parasites?
-
Does parasite prevalence differ by geographic region?
-
Are specific host genotypes more resistant to parasite infection?
SEM of Lotmaria passim (image credit: Ryan Schwarz 2015)
Genome Statistics of Selected Trypanosomatid Parasites (Subfamily: Leishmaniinae)
03
Genomic insights into the evolution of infectious disease agents
While in vitro and in vivo studies are essential to answering many of the questions surrounding the ecology of trypanosomatid parasites, bioinformatic studies are just as important to begin to understand their evolutionary history. My work assembling and annotating the genome for the Lotmaria passim strain BRL (2024) reference species has helped to fill gaps where culture-based methods and live infection assays can be limited, and now acts as a tool for future studies.
​
Fellow lab members are now using this resource to focus on sequencing, assembling, and annotating a database of high quality, chromosome-level assemblies with comprehensive annotations to begin to assess the evolutionary history of these pathogens.
Specifically, our lab’s work will aim to develop the evolutionary understanding of monoxenous trypanosomatids by assessing known and novel gene families critical to:
-
Transmission, invasion, and colonization of hosts both independently and in relation to host symbionts
-
Tolerance to thermal stress
-
Resistance to antiparasitic drugs