Viruses are ubiquitous in the world􀁅s oceans, playing an essential role in biogeochemical processes while representing a vast source of genetic diversity. Yet we still know little about natural…

This is a grant awarded by the National Aeronautics and Space Administration (NASA) Shared Services Center to the J. Craig Venter Institute, Inc., a not-for-profit genomic research institute, for a two-year project focused on examining the lifestyle and impact of viruses on microbial communities in the subseafloor of deep-sea hydrothermal vents. The project will investigate DNA and RNA viruses, including identifying novel RNA viruses, to better understand virus-host interactions and the role of viral communities in the subseafloor. The $235,675 grant does not have a set-aside designation and is part of NASA's Exobiology and Evolutionary Biology program, which supports research on extremophilic organisms and their potential relevance to the origin and evolution of life on Earth and other planetary bodies.

Viruses are ubiquitous in the world􀁅s oceans, playing an essential role in biogeochemical processes while representing a vast source of genetic diversity. Yet we still know little about natural viral communities. Hydrothermal systems have been prevalent on earth since the planet was formed and its hypothesized that life may have originated and evolved near deep-sea hydrothermal vents, making them the most ancient continuously inhabited ecosystems on the planet. Extant organisms living in these analogues of early habitats may still harbor genetic and metabolic characteristics of early life. Viruses play a critical role in the ultimate survival of microbes by mediating host functional diversification and enhancing adaptability via horizontal gene transfer and lysogeny, a replication strategy enabling the virus to incorporate its genome into their hosts (prophage). In this project, we will examine the lifestyle and impact of viruses on microbial communities in the subseafloor of deep-sea hydrothermal vents. We will investigate DNA and RNA viruses, the latter comprising the most ancient group of viruses on our planet. Our research plan will determine infection dynamics and interrogate host associations, both of which are known to lead to physiological alterations and wide-ranging evolutionary trajectories. Specific goals we plan to address include, i) determine phage host range and specificity to diverse microbial host isolates from deep-sea hydrothermal vents II) determine role of vent viruses in microbial host evolution and ecology at deepsea hydrothermal vents III) identify novel RNA viruses from deep-sea hydrothermal vents. Elucidation of these goals will allow US to better constrain the impact of viral communities in the subseafloor and examine the nature of virus-host interactions as models for understanding early life. We will use viral infection studies to experimentally investigate isolates from a phylogenetically diverse collection of cultured vent microbes, including both bacteria and archaea. The existing culture collection will facilitate testing host-ranges of viral isolates, indicating possible evolutionary breakpoints of viral transfer. Cultured isolates will be interrogated using prophage induction assays and challenge experiments followed by sequencing and microscopy. To identify the host range/specificity of phage isolated, phage will be mixed within and between related host microbial genera. Increases in phage titers will be measured to evaluate amplification during infection. Genomic-based technologies of viruses and microbes will be leveraged to interrogate viruses, their hosts, and interactions. We will computationally interrogate omics information for evidence of viral-mediated cellular gene transfer and lysogenic conversion, and host immunity markers resulting from past infection. Finally, RNA viruses, including retroviruses, will be characterized via homology binning and phylogenetics from community metagenomic, transcriptomic data. The study of extremophilic organisms and their metabolic pathways, habitats, and distribution is essential to understanding the origin and evolution of life on earth, the main goal of NASA􀁅s exobiology and evolutionary biology program. Viruses are important evolutionary drivers of natural microbial communities, and examinations of viral communities in the rock-hosted oceanic subseafloor are just beginning that hold great promise for revealing new information about remote life on earth and the possibilities for life on other planetary bodies. Outreach activities include training undergraduate students at a small liberal arts college in cutting-edge genomics and bioinformatics techniques and developing an extreme virus module for elementary school students