Meeting Abstract
Coral-associated microbes (e.g., dinoflagellates in the family Symbiodiniaceae, bacteria) contribute to the health and function of their host colonies. Yet, during acute periods of environmental stress, microbial partners can shift or dissociate entirely from hosts, causing colony disease/bleaching and mortality. Shifts in coral-associated viruses are also likely to correlate with differences in coral and reef health, yet relatively few studies target this group. We are exploring the diversity of coral- and dinoflagellate-associated viruses in a range of Pacific and Caribbean host species, in healthy and diseased/bleached coral tissues, and in laboratory cultures of Symbiodiniaceae. We recently examined actively transcribing viruses from the coral, Pocillopora verrucosa, and recovered OTUs that aligned with 108 distinct viral groups at several taxonomic levels in a single host colony using RNA-Seq. Viral reads processed to date were dominated by phage (~94%) but also included similarities to members of the Megaviridae, Pandoraviridae, and Alvernaviridae, all of which likely infect Symbiodiniaceae. We characterized lineage-specific diversity in a positive single-stranded RNA virus (Alvernaviridae) in five P. verrucosa genets exposed to control and thermal stress treatments using nested degenerate primers and amplicon sequencing, and identified ~2,400 ASVs (N = 55 coral fragments total), and found that the community composition of these viruses is more strongly correlated with coral genet than thermal stress. There have been challenges in confirming the roles of coral-associated viruses, due to the techniques applied and difficulties in culturing these viruses. We discuss the importance of developing a cnidarian-dinoflagellate-virus model system in order to advance our understanding of the roles of viruses in corals and other hosts.
