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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #424916
Research Project: Maximizing Profitability and Fish Health in Catfish Aquaculture

Location: Warmwater Aquaculture Research Unit

Title: Molecular confirmation of Henneguya adiposa and associated histologic changes in adipose fins of channel catfish, Ictalurus punctatus

Author
item STILWELL, JUSTIN - University Of Georgia
item CAMUS, ALVIN - University Of Georgia
item LEARY, JOHN - University Of Georgia
item MOHAMMED, HAITHAM - Auburn University
item GRIFFIN, MATT - Mississippi State University

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2019
Publication Date: 3/22/2019
Citation: Stilwell, J.M., Camus, A.C., Leary, J.H., Mohammed, H.H., Griffin, M.J. 2019. Molecular confirmation of Henneguya adiposa and associated histologic changes in adipose fins of channel catfish, Ictalurus punctatus. Parasitology Research. 118 1639-2019. https://doi.org/10.1007/s00436-019-06295-w.
DOI: https://doi.org/10.1007/s00436-019-06295-w

Interpretive Summary: Identifying the myxozoan community in catfish aquaculture is crucial for managing fish health and understanding parasite-associated tissue damage. This study confirms Henneguya adiposa infections in the adipose fins of channel catfish, describing the granulomatous inflammation and connective tissue damage caused by the parasite. While H. adiposa is not linked to mortality, understanding its pathology and dispersal mechanisms, as well as identifying molecular probes to track its development in the fish host, can help clarify host/parasite interactions and inform monitoring strategies to mitigate the potential impacts of myxozoan parasitism on catfish production.

Technical Abstract: Henneguya adiposa is one of ten known, closely related myxozoan species that parasitize a variety of tissue sites in the channel catfish, Ictalurus punctatus. Reported to specifically target the adipose fin, H. adiposa is not associated with morbidity or mortality, although detailed descriptions of its associated histologic pathology are lacking. The objective of this work was to confirm the presence of H. adiposa within fin lesions of affected channel catfish using DNA sequenced from histologic sections obtained by laser capture microdissection, as well as to describe pathologic changes induced by infection. The parasite formed large, white, elongate, nodular plasmodia that caused localized tissue damage and incited a granulomatous inflammatory response within a deep connective tissue layer at the base of the adipose fin. Myxospores released from ruptured plasmodia into adjacent tissue were observed to migrate superficially in tracts through the skin, indicating a portal of exit for environmental dispersal. Defects in the connective tissue layer created by ruptured plasmodia were infiltrated by granulomatous inflammation and fibroplasia, suggesting lesion resolution by scar formation over time. Sequencing of the 18S rRNA gene amplified from excised myxospores confirmed the myxozoan’s identity as H. adiposa, with 100% similarity to the reference sequence from previous published work.