Ciliated protozoan occurrence and association in the pathogenesis of coral disease

Ravindran, Chinnarajan; Raveendran, Haritha P.; Irudayarajan, Lawrance

doi:10.1016/j.micpath.2021.105211

Cited by 10 publications

(8 citation statements)

References 70 publications

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“…Recently, Philaster spp. have been consistently found in association with several coral diseases, ingesting host cells (18)(19)(20)(21)(22)29) and potentially acquiring zooxanthellae from ingested corals (20). Ciliates have been observed in urchin digestive tracts as far back as 1932 (30,31), but Philaster spp.…”

Section: Discussionmentioning

confidence: 99%

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea

et al. 2023

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Echinoderm mass mortality events shape marine ecosystems by altering the dynamics among major benthic groups. The sea urchin Diadema antillarum , virtually extirpated in the Caribbean in the early 1980s by an unknown cause, recently experienced another mass mortality beginning in January 2022. We investigated the cause of this mass mortality event through combined molecular biological and veterinary pathologic approaches comparing grossly normal and abnormal animals collected from 23 sites, representing locations that were either affected or unaffected at the time of sampling. Here, we report that a scuticociliate most similar to Philaster apodigitiformis was consistently associated with abnormal urchins at affected sites but was absent from unaffected sites. Experimentally challenging naïve urchins with a Philaster culture isolated from an abnormal, field-collected specimen resulted in gross signs consistent with those of the mortality event. The same ciliate was recovered from treated specimens postmortem, thus fulfilling Koch’s postulates for this microorganism. We term this condition D. antillarum scuticociliatosis.

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Section: Discussionmentioning

confidence: 99%

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea

et al. 2023

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“…The remaining taxa identified in this survey reflect previous observations of ciliates associated with Diadema antillarum. Licnophora macfarlandi has been observed in association with coral disease (Sweet & Séré 2016, Ravindran et al 2022), and may constitute a cosmopolitan taxon in coral reef settings. Parametopidium spp.…”

Section: Resultsmentioning

confidence: 99%

Design and validation of a PCR protocol to specifically detect the clade ofPhilastersp. associated withDiadema antillarumscuticociliatosis

Vilanova-Cuevas,

Reyes-Chavez,

Breitbart

et al. 2023

Preprint

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Diadema antillarumscuticociliatosis (DaSc), caused by a scuticociliate closely related toPhilaster apodigitiformis, has affected Caribbean long-spined urchins since at least January 2022. Quantitative PCR (qPCR) is currently the standard method for detection of this ciliate in tissue and coelomic fluid samples, yet this method requires specialized equipment and is more expensive than standard PCR methods. The DaSc scuticociliate occurs against a backdrop of endo- and ecto-symbiotic ciliates which complicate detection using universal or pan-phylum PCR primer sets. To overcome these limitations, we designed and validated a sensitive and specific PCR primer (scutico-634F) and nested two-step PCR protocol to detect this taxon, which excludes other ciliates associated withD. antillarumand has poor affinity for other related ciliates. This primer and protocol for the DaSc-associated Philaster clade (DaScPc) allow for widely-accessible investigation of this pathogen in new regions and within environmental reservoirs.

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“…Besides, they influence the disease severity on the immune-compromised coral tissues [80] and forage on the tissue lesions including the endosymbiont Symbiodiniaceae [81][82][83]. Thus, ciliates are generally believed to be opportunistic pathogens [84,85]. Numerous ciliates related to coral disease have been identified in the Caribbean and Indo-Pacific.…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial activity of coral‐associated beneficial bacteria against coral disease‐causing microbial pathogens

Irudayarajan,

Ravindran,

Raveendran

2023

J Basic Microbiol

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Microbial infection of immune‐compromised corals influences disease severity, resulting in coral mortality. However, coral‐associated beneficial bacteria are known to produce antimicrobial compounds that prevent the growth of potential pathogens and invading microbes. Hence, beneficial bacteria associated with coral Porites lutea were isolated and antimicrobial protein and bioactive secondary metabolites were extracted and tested for their antimicrobial activity against putative prokaryotic and eukaryotic coral pathogens. Bioactive secondary metabolites exhibited remarkable antagonism against various coral pathogens such as Serratia marcescens, Vibrio species, and Aspergillus sydowii. Besides, the metabolites of Cobetia marina, Cobetia amphilecti, Pseudoalteromonas neustonica, and Virgibacillus halodenitrificans manifested notable inhibition against the protozoan ciliates (Uronema marinum, Holosticha diademata, Cohnilembus verminus, and Euplotes vannus) and zooplankton that are known to be involved in the secondary pathogenesis in coral diseased lesion progression. Thus, the present study may benefit in understanding coral‐associated beneficial bacteria for their antagonistic interactions with microbial pathogens, as well as their potential involvement in reducing coral disease severity.

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Ciliated protozoan occurrence and association in the pathogenesis of coral disease

Cited by 10 publications

References 70 publications

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea

A scuticociliate causes mass mortality of Diadema antillarum in the Caribbean Sea

Design and validation of a PCR protocol to specifically detect the clade ofPhilastersp. associated withDiadema antillarumscuticociliatosis

Antimicrobial activity of coral‐associated beneficial bacteria against coral disease‐causing microbial pathogens

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