Comparison of Viral Metagenomes from Bleached and Non-Bleached Pocillopora spp. Corals

Coral reefs are vital ecosystems that are rapidly declining due to disease and bleaching. Viruses are known to have many roles in marine ecosystems, however, their roles in corals are less understood. This work investigates viral metagenomes from both bleached and non-bleached corals. These coral phenotypes were found during a bleaching event, where one bleached colony was directly adjacent to another non-bleached colony. We conducted viral community analysis during this paradoxical bleaching pattern and found that bleached corals had a higher relative percent abundance of similarities to eukaryotic virus sequences, and non-bleached corals had a higher relative percent abundance of similarities to bacteriophage sequences. We also found that bleached metagenomes had higher sequence similarities to nucleocytoplasmic large DNA viruses (NCLDVs). We initiated the genome assembly of the first coral NCLDV, which we believe is distantly related to other marine NCLDVs, and may play a role in coral bleaching. Uncovering a novel coral NCLDV and gaining a better understanding of viral community dynamics will aid in further investigations to elucidate the role of viruses in coral ecosystem health.