Myxozoan Community Composition and Diversity in Clinical Cases of Proliferative Gill Disease in Mississippi Catfish Aquaculture

Stilwell, Justin M.; Griffin, Matt J.; Waldbieser, Geoffrey C.; Stanton, James B.; Leary, John H.; Khoo, Lester H.; Steadman, James; Ware, Cynthia; Wise, David J.; Camus, Alvin C.

doi:10.1645/21-57

Cited by 6 publications

(32 citation statements)

References 43 publications

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“…Among these 14 unclassified OTUs, 11 were also identified in gill samples from clinical PGD cases in an ancillary study (100% sequence identity; Stilwell et al. 2022). Matching OTU sequences from each data set are summarized in Supplementary Table 4.…”

Section: Resultsmentioning

confidence: 99%

“…Asterisks represent OTUs with 100% nucleotide similarity to those identified in proliferative gill disease cases (Stilwell et al. 2022). Branch values represent maximum likelihood analysis using the Hasegawa–Kishino–Yano model with a discrete gamma distribution and bootstrap confidence values obtained from 1,000 pseudoreplicates.…”

Section: Resultsmentioning

confidence: 99%

“…exilis infection, should provide more resolute assessments of myxozoan community dynamics contributing to myxozoan diseases in farm‐raised catfish (Stilwell et al. 2022).…”

Section: Discussionmentioning

confidence: 99%

“…2001) and reverse primer (1862R; 5’‐ATTGTAGCGCGCGTGCAG‐3′; Stilwell et al. 2022) targeted highly conserved regions of the myxozoan 18S rRNA gene that flank a diagnostic hypervariable region used for identifying species of myxobolid myxozoans (Iwanowicz et al. 2008; Griffin et al.…”

Section: Methodsmentioning

confidence: 99%

“…2020; Stilwell et al. 2022), although reports from the Aquatic Research and Diagnostic Laboratory at NWAC indicate that PGD is diagnosed in Channel Catfish at twice the rate of hybrids (L. H. Khoo, unpublished data). The objective of this study was to identify the extent to which the catfish host influences myxozoan community composition in Channel Catfish and hybrid catfish monoculture systems.…”

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confidence: 99%

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Influence of Channel Catfish and Channel × Blue Catfish Hybrids on Myxozoan Community Composition in Catfish Aquaculture Ponds

et al. 2023

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The myxozoan Henneguya ictaluri is cited as the cause of proliferative gill disease (PGD) in Channel Catfish Ictalurus punctatus and Channel × Blue Catfish I. furcatus hybrids. Differences in host susceptibility result in decreased transmission rates, reduced sporogenesis, and lesser incidence of PGD in hybrid catfish. In experimental pond trials, continuous monoculture of hybrid catfish suppressed H. ictaluri abundance in pond systems compared to Channel Catfish monoculture. The present study examined differences in myxozoan community structure in catfish ponds stocked with Channel Catfish or hybrid catfish. Experimental ponds (0.4 ha) dedicated to Channel Catfish or hybrid catfish monoculture were maintained over three production cycles. Pond water collected during the spring of each year was subjected to metagenomic analysis by targeted amplicon sequencing of a diagnostic hypervariable region (DVR3) of the myxozoan 18S ribosomal RNA gene. Relative abundance of H. ictaluri was significantly greater in Channel Catfish ponds than in hybrid catfish ponds during years 2 and 3. In hybrid catfish ponds, H. ictaluri never exceeded 20% average relative abundance. Hybrid catfish ponds also revealed decreased myxozoan diversity and species evenness compared to Channel Catfish ponds, suggesting that myxozoan taxa associated with Channel Catfish may not be well adapted to the hybridized host. Results corroborate previous research indicating that hybrid catfish monoculture can suppress H. ictaluri compared to ponds that are devoted to Channel Catfish. These data imply that alternating catfish culture species in ponds (crop rotation) has the potential to mitigate PGD by precluding H. ictaluri from accumulating within ponds to levels associated with disease and catastrophic loss. Further, this work identified numerous previously unidentified taxa present within these systems that clustered phylogenetically with both catfish and noncatfish hosts. The impacts that these other myxozoans have on catfish health and production are unknown, but their presence indicates that myxozoan diversity within catfish aquaculture ponds has been greatly underestimated and is significantly influenced by stocking choice.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…exilis infection, should provide more resolute assessments of myxozoan community dynamics contributing to myxozoan diseases in farm‐raised catfish (Stilwell et al. 2022).…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Influence of Channel Catfish and Channel × Blue Catfish Hybrids on Myxozoan Community Composition in Catfish Aquaculture Ponds

et al. 2023

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Species‐specific in situ hybridization confirms arrested development of Henneguya ictaluri in hybrid catfish (Channel Catfish × Blue Catfish) under experimental conditions, with notes on mixed‐species infections in clinical cases of proliferative gill disease from Mississippi catfish aquaculture

Stilwell,

Camus,

Woodyard

et al. 2023

J Aqua Anim Hlth

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ObjectiveProliferative gill disease (PGD) in Channel Catfish Ictalurus punctatus and hybrid catfish (Channel Catfish × Blue Catfish I. furcatus) is attributed to the myxozoan Henneguya ictaluri. Despite evidence of decreased H. ictaluri transmission and impaired parasite development in hybrid catfish, PGD still occurs in hybrid production systems. Previous metagenomic assessments of clinical PGD cases revealed numerous myxozoans within affected gill tissues in addition to H. ictaluri. The objective of this study was to investigate the development and pathologic contributions of H. ictaluri and other myxozoans in naturally and experimentally induced PGD.MethodsHenneguya species‐specific in situ hybridization (ISH) assays were developed using RNAscope technology. Natural infections were sourced from diagnostic case submissions in 2019. Experimental challenges involved Channel Catfish and hybrid catfish exposed to pond water from an active PGD outbreak, and the fish were sampled at 1, 7, 10, 12, 14, 16, 18, and 20 weeks postchallenge.ResultNine unique ISH probes were designed, targeting a diagnostic variable region of the 18S ribosomal RNA gene of select myxozoan taxa identified in clinical PGD cases. Partial validation from pure H. ictaluri, H. adiposa, H. postexilis, and H. exilis infections illustrated species‐specific labeling and no cross‐reactivity between different myxozoan species or the catfish hosts. After experimental challenge, mature plasmodia of H. ictaluri and H. postexilis formed in Channel Catfish but were not observed in hybrids, suggesting impaired or delayed sporogenesis in the hybridized host. These investigations also confirmed the presence of mixed infections in clinical PGD cases.ConclusionAlthough H. ictaluri appears to be the primary cause of PGD, presporogonic stages of other myxozoans were also present, which may contribute to disease pathology and exacerbate respiratory compromise by further altering normal gill morphology. This work provides molecular confirmation and more resolute developmental timelines of H. ictaluri and H. postexilis in Channel Catfish and supports previous research indicating impaired or precluded H. ictaluri sporogony in hybrid catfish.

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Henneguyosis: A novel threat to the exotic channel catfish Ictalurus punctatus cultivated in China

Zhang

2023

Aquaculture

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Myxozoan Community Composition and Diversity in Clinical Cases of Proliferative Gill Disease in Mississippi Catfish Aquaculture

Cited by 6 publications

References 43 publications

Influence of Channel Catfish and Channel × Blue Catfish Hybrids on Myxozoan Community Composition in Catfish Aquaculture Ponds

Influence of Channel Catfish and Channel × Blue Catfish Hybrids on Myxozoan Community Composition in Catfish Aquaculture Ponds

Henneguyosis: A novel threat to the exotic channel catfish Ictalurus punctatus cultivated in China

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