In recent years microbiologists have become aware of abundant "giant viruses" that infect protists. These viruses have also been implicated as components of the microbiomes of multicellular organisms. Many of the genes within these giants are considered novel for viruses: many genes encode for processes only associated with "living cellular organisms," like DNA replication or DNA repair, are found in these viruses. Studies suggest that these giant viruses have collected these genes from across all biology, leaving these viruses with genomes that can at best be described as mosaics. Moreover many of the hundreds of genes found in giant viruses remain completely new to science. In spite of this obvious wealth of information, we remain without tools to study how these giant virus genes function or if they are even necessary. This study will develop the tools needed to do genetic research in a model giant virus system (the Aureococcus anophagefferens Virus) and establish the ability of these tool sets to be extended to other giant viruses and their hosts.
While discovered only 15 years ago, giant viruses infecting protists have been shown to be distributed across ecosystems. These viruses contain functional genes encoding processes that can include light-dependent and independent DNA repair, sugar metabolism genes and genes associated with the process of translation. Phylogenetic examinations suggest these genes have been collected by rampant horizontal gene transfer. This study will develop protocols required to test gene function and activity in a giant virus (AaV) that infects the pelagophyte Aureococcus anophagefferens. A member of the Mimiviridae, AaV is a large virus with a complex complement of genes. The PIs and trainees will develop in vitro approaches to modify and transform AaV, including the introduction of antibiotic resistance and/or chromogenic/fluorogenic proteins for genetically tractable selections for use in subsequent gene replacement studies. The PIs will test protocols on other Mimiviridae and Phycodnaviridae that infect algae to determine tractability in other giant virus-host systems. Along with training of a postdoc, graduate and undergraduate students, this project will develop tools that allow for hypothesis driven testing in subsequent studies in a system where many (> 60%) of the gene products are annotated as hypothetical. The project will communicate protocols through training sessions as well as a dedicated workshop, and document all approaches in open access through protocols.io. Student journalists will produce material for public consumption, including short videos focusing on the positive role of viruses in ecology, the importance of technical reproducibility in science, and several on the fascinating nature of giant viruses.
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.
