Browsing by Author "Thurber, Andrew R."

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    Coral Bleaching Phenotypes Associated With Differential Abundances of Nucleocytoplasmic Large DNA Viruses
    (Frontiers, 2020) Messyasz, Adriana; Rosales, Stephanie M.; Mueller, Ryan S.; Sawyer, Teresa; Correa, Adrienne M.S.; Thurber, Andrew R.; Thurber, Rebecca Vega
    Eukaryotic viruses and bacteriophage have been implicated in disease and bleaching in corals, but the compositional and functional diversity of these viruses in healthy and compromised hosts remains underexplored. To investigate whether viral assemblages differ in concert with coral bleaching, we collected bleached and non-bleached conspecific pairs of corals during a minor bleaching event in 2016 from reefs on the island of Mo’orea, French Polynesia. Using electron microscopy (EM), we identified several viral particle types, all reminiscent of medium to large-sized nucleocytoplasmic large DNA viruses (NCLDV). We also found that viral metagenomes from bleached corals have significantly more eukaryotic virus sequences, whereas bacteriophage sequences are significantly more abundant in viral metagenomes from non-bleached colonies. In this study, we also initiated the assembly of the first eukaryotic dsDNA coral virus genome. Based on our EM imagery and our taxonomic annotations of viral metagenome sequences, we hypothesize that this genome represents a novel, phylogenetically distinct member of the NCLDVs, with its closest sequenced relative being a distant marine flagellate-associated virus. We also showed that this NCLDV is abundant in bleached corals, but it is also present in apparently healthy corals, suggesting it plays a role in the onset and/or severity of coral bleaching.
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    Filamentous virus-like particles are present in coral dinoflagellates across genera and ocean basins
    (Oxford University Press, 2023) Howe-Kerr, Lauren I.; Knochel, Anna M.; Meyer, Matthew D.; Sims, Jordan A.; Karrick, Carly E.; Grupstra, Carsten G. B.; Veglia, Alex J.; Thurber, Andrew R.; Vega Thurber, Rebecca L.; Correa, Adrienne M. S.
    Filamentous viruses are hypothesized to play a role in stony coral tissue loss disease (SCTLD) through infection of the endosymbiotic dinoflagellates (Family Symbiodiniaceae) of corals. To evaluate this hypothesis, it is critical to understand the global distribution of filamentous virus infections across the genetic diversity of Symbiodiniaceae hosts. Using transmission electron microscopy, we demonstrate that filamentous virus-like particles (VLPs) are present in over 60% of Symbiodiniaceae cells (genus Cladocopium) within Pacific corals (Acropora hyacinthus, Porites c.f. lobata); these VLPs are more prevalent in Symbiodiniaceae of in situ colonies experiencing heat stress. Symbiodiniaceae expelled from A. hyacinthus also contain filamentous VLPs, and these cells are more degraded than their in hospite counterparts. Similar to VLPs reported from SCTLD-affected Caribbean reefs, VLPs range from ~150 to 1500 nm in length and 16–37 nm in diameter and appear to constitute various stages in a replication cycle. Finally, we demonstrate that SCTLD-affected corals containing filamentous VLPs are dominated by diverse Symbiodiniaceae lineages from the genera Breviolum, Cladocopium, and Durusdinium. Although this study cannot definitively confirm or refute the role of filamentous VLPs in SCTLD, it demonstrates that filamentous VLPs are not solely observed in SCTLD-affected corals or reef regions, nor are they solely associated with corals dominated by members of a particular Symbiodiniaceae genus. We hypothesize that filamentous viruses are a widespread, common group that infects Symbiodiniaceae. Genomic characterization of these viruses and empirical tests of the impacts of filamentous virus infection on Symbiodiniaceae and coral colonies should be prioritized.