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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #425703
Research Project: Maximizing Profitability and Fish Health in Catfish Aquaculture

Location: Warmwater Aquaculture Research Unit

Title: Genetic characterization of heterologous edwardsiella piscicida isolates from diverse fish hosts and virulence assessment in a chinook salmon oncorhynchus tshawytscha model

Author
item NGUYEN, DIEM - University Of California, Davis
item LOPEZ-PORRAS, ADRIAN - Mississippi State University
item MARANICK, DAVID - St George'S University
item HAWKINS, LEIGHANNE - Cooke Aquaculture
item WELCH, TIMOTHY - USDA-ARS Sino-american Biological Control Laboratory
item PETTY, BARBARA - North Florida Research & Education Center
item WARE, CYNTHIA - Mississippi State University
item GRIFFIN, MATT - Mississippi State University
item SOTO, ESTEBAN - University Of California, Davis

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2021
Publication Date: 12/1/2021
Citation: Nguyen, D.T., Lopez-Porras, A., Maranick, D., Hawkins, L., Welch, T.J., Petty, B.D., Ware, C., Griffin, M.J., Soto, E. 2021. Genetic characterization of heterologous Edwardsiella piscicida isolates from diverse fish hosts and virulence assessment in a Chinook salmon Oncorhynchus tshawytscha model. Journal of Fish Diseases. 44(12):1959-1970. https://doi.org/10.1111/jfd.13509.
DOI: https://doi.org/10.1111/jfd.13509

Interpretive Summary: Edwardsiella piscicida is a warm-water pathogen primarily affecting U.S. farm-raised catfish but has also been reported in other aquaculture systems, including coldwater salmonid culture. This study examined the genetic and virulence diversity of E. piscicida isolates from multiple fish species, revealing six distinct genetic clades with variable pathogenicity in Chinook salmon. Findings highlight the potential for strain-specific host associations and emphasize the need for further research to understand transmission risks and disease management across different aquaculture environments.

Technical Abstract: Edwardsiella piscicida is an emergent global fish pathogen with a wide host range, although host associations driving genetic diversity remain unclear. This study investigated the genetic and virulence diversity of 37 E. piscicida isolates recovered from 10 fish species in North America. Multilocus sequence analysis (MLSA) was conducted using concatenated alignments of the gyrB, pgi and phoU sequences. MLSA clustered the tested isolates into six discrete clades. In light of recent disease outbreaks in cultured salmonids, the virulence of each clade was evaluated in Chinook salmon Oncorhynchus tshawytscha fingerlings following intracoelomic challenge of ~106 CFU/fish. Challenged and control fish were monitored for 21d, and microbiological and histological examination was performed on dead and surviving fish. Peak mortality occurred 3-5 days post-challenge (dpc) regardless of isolate or genetic group. Edwardsiella iscicida was recovered from all moribund and dead animals. At 21 dpc, fish challenged with isolates from clades II, III and IV presented cumulative mortality =83.3%, whereas isolates from clade I, V and VI resulted in cumulative mortality =71.4%. This study suggests an underlying genetic basis for strain virulence and potential host associations. Further investigations using other fish models and variable challenge conditions are warranted.