Christopher M. DeRito
Isabella T. Ritchie
Christina A. Kellogg
James S. Evans
Alizee Zimmermann
Stacey M. Williams
Marilyn E. Brandt
Moriah L. B. Sevier
Samuel Gittens
Kayla A. Budd
Matthew Warham
William C. Sharp
Gabriel A. Delgado
Alwin Hylkema
Kimani A. Kitson-Walters
Jean-Pascal Quod
Mya Breitbart
Ian Hewson
Brayan Vilanova-Cuevas
2025
<p><span>Mass mortality of Diadematidae urchins, caused by the </span><i>Diadema antillarum</i><span> scuticociliatosis Philaster clade (DScPc)</span><i>,</i><span> affected the Caribbean in spring 2022 and subsequently spread to the eastern Mediterranean, Red Sea, and western Indian Ocean. A key question around Diadematidae scuticociliatosis (DSc), the disease caused by the scuticociliate, is whether the urchin microbiome varies between scuticociliatosis-affected and grossly normal urchins. Tissue samples from both grossly normal and abnormal </span><i>Diadema antillarum</i><span> were collected in the field during the initial assessment of the DSc causative agent and from an experimental challenge of DScPc culture on aquacultured </span><i>D. antillarum</i><span>. Specimens were analyzed using 16S rRNA gene amplicon sequencing. Additional abnormal urchin samples were collected from the most recent outbreak site in the western Indian Ocean (Réunion Island). At reference (i.e., unaffected by DSc) sites, </span><i>Kistimonas</i><span> spp.</span><i>, Propionigenium</i><span> spp., and </span><i>Endozoicomonas</i><span> spp. were highly represented in amplicon libraries. DSc-affected urchin amplicon libraries had lower taxonomic richness and a greater representation of taxa related to </span><i>Fangia hongkongensis</i><span> and </span><i>Psychrobium</i><span> spp. Amplicon libraries of urchins experimentally challenged with the DSc pathogen had some shifts in microbial composition, but </span><i>F. hongkongensis</i><span> was not a part of the core bacteria in DSc-challenged specimens. DSc-affected </span><i>Echinothrix diadema</i><span> from Réunion Island showed a similar high representation of </span><i>F. hongkongensis</i><span> as that seen on Caribbean </span><i>D. antillarum</i><span>. Our results suggest that DSc alters </span><i>Diadematidae</i><span> microbiomes and that </span><i>F. hongkongensis</i><span> may be a candidate bacterial biomarker for DSc in environmental samples. The mechanism driving microbiome variation in host–pathogen interactions remains to be explored.</span></p>
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10.1128/msystems.01418-24
en
American Society for Microbiology
Investigating the influence of Diadematidae scuticociliatosis on host microbiome composition
article