Emergence of a Novel Virus Following Long-Term Experimental Soil Warming


Presenter: Vartika Burman

Faculty Sponsor: Jeffrey Blanchard

School: UMass Amherst

Research Area: Biological Organisms

Session: Poster Session 1, 10:30 AM - 11:15 AM, 163, C25

ABSTRACT

Virophages, a group of double-stranded DNA viruses, hijack the replicative machinery of giant viruses (GVs) and rely on them to enter and replicate inside of host protists. They are studied primarily in aquatic environments, and little is known regarding their role in soil environments. To bridge this gap in research, virophages were identified in metagenomes from the Barre Woods soil warming experiment which was designed to study the evolution of soil microbiomes in the context of climate change. This was done by maintaining the heated plot 5°C higher than the control to simulate global climate change projections. DNA was extracted from these soil samples and sent to the Joint Genome Institute (JGI) for library preparation and sequencing. In this dataset, we found 33 different virophage vOTUs. After differential abundance for each vOTU was tested, one vOTU, which we termed “Imagivirus”, existed solely in the heated plots and was significantly overrepresented (p = 0.00029). Four major conserved genes were identified (major and minor capsid, cysteine protease, and ATPase), and most of the hypothetical genes were not shared with other vOTUs after genome arrangement visualization. Hypotheses which may explain Imagivirus’s differential abundance in the soil include an observed elevated bacteria:fungi ratio which suggests potential host protist populations may proliferate leading to subsequent increase in GVs and virophages. Alternatively virophages may exist as free particles in the soil or as abundant replicons inside a host cell as they are surprisingly abundant in soil samples, compared to GVs and protists.

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