Unravelling the Complex Interactions of Algal Viruses and Their Hosts

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Globally, microalgae, or phytoplankton, are the most important aquatic primary producers. They are critical to human affairs because they convert inorganic material into organic thereby fueling marine and freshwater food webs. Their growth determines the productivity and quality of aquatic environments, and their beneficial use by human by sustaining fisheries or forming nuisance algal blooms, as examples. In the 1990s, biological oceanographers discovered that viruses infecting algae are abundant in nearly all aquatic environments and most of them are highly species-specific and lyse, or kill, their algal hosts. These discoveries raised many questions about the influence of viruses on aquatic food webs and their role in algal ecology and evolution. Ongoing research has demonstrated that viral infections of algae can directly and indirectly affect species competition, nutrient cycling in aquatic environments, and algal evolution. Evidence is accumulating that algal viruses and their hosts interact in a dynamic manner, each influencing the growth and evolution of the other, yet their interactions are complex and rarely predictable, so many fundamental questions remain unanswered. The long-term goal of my research program is to advance knowledge of algal virus' interactions with their hosts. These studies will enhance our ability to predict the composition and dynamics of phytoplankton communities and the ecosystems services they provide. In the coming years, my research team will focus on specific, tractable objectives encompassed by my program's long-term goal. These include studies of the environmental persistence of algal viruses, characterizing a consortium of algal viruses that my group discovered and isolated from Lake Ontario, and characterizing the genetic capabilities and activities of these viruses. The experiments we will conduct to fulfill these objectives involve laboratory-based cultivation and environmental sampling, and various molecular biology and cell biology tools like quantitative PCR, transmission electron microscopy, and genome sequencing and gene expression studies facilitated by Next-Generation Sequencing. Our ability to advance understanding of virus-algae interactions is greatly enhanced by my research group's recent isolation of viruses that infect a globally relevant freshwater microalgae, and the discovery that we have in our possession a consortium of different viruses and virophages, viruses that co-infect host cells and indirectly parasitizes other viruses! These projects will provide training opportunities for highly sought research techniques ranging from environmental monitoring to molecular biology. My research will inform models of aquatic ecosystems by enhancing our understanding of the role of viruses in primary production and will teach us how the environment influences virus activity. More broadly, our studies will contribute to advancing knowledge of virus ecology and evolution, and viral pathogenesis.