Genetic variability of Edwardsiella piscicida isolates from Mississippi catfish aquaculture with an assessment of virulence in channel and channel × blue hybrid catfish. Issue 11 (12th July 2021)

• Record Type: Journal Article
• Authors: López‐Porras, Adrián; Griffin, Matt J.; Armwood, Abigail R.; Camus, Alvin C.; Waldbieser, Geoffrey C.; Ware, Cynthia; Richardson, Bradley; Greenway, Terrence E.; Rosser, Thomas Graham; Aarattuthodiyil, Suja; Wise, David J.
• Is Part Of: Journal of fish diseases. Volume 44:Issue 11(2021)
• Page Start: 1725
• Page End: 1751
• Publication Date: 2021-07-12
• Subjects: Edwardsiella piscicida -- edwardsiellosis -- hybrid catfish -- Ictalurus punctatus -- multilocus sequence analysis -- rep‐PCR -- virulence; Fishes -- Diseases -- Periodicals; 639.3
• DOI: 10.1111/jfd.13491
• Languages: English
• ISSNs: 0140-7775

Abstract

Abstract: The bacterium Edwardsiella piscicida causes significant losses in global aquaculture, particularly channel ( Ictalurus punctatus ) × blue ( I . furcatus ) hybrid catfish cultured in the south‐eastern United States. Emergence of E . piscicida in hybrid catfish is worrisome given current industry trends towards increased hybrid production. The project objectives were to assess intraspecific genetic variability of E . piscicida isolates recovered from diseased channel and hybrid catfish in Mississippi; and determine virulence associations among genetic variants. Repetitive extragenic palindromic sequence‐based PCR (rep‐PCR) using ERIC I and II primers was used to screen 158 E . piscicida diagnostic case isolates. A subsample of 39 E . piscicida isolates, representing predominant rep‐PCR profiles, was further characterized using BOX and (GTG)5 rep‐PCR primers, virulence gene assessment and multilocus sequence analysis (MLSA) targeting housekeeping genes gyrb, pgi and phoU . The MLSA provided greater resolution than rep‐PCR, revealing 5 discrete phylogroups that correlated similarly with virulence gene profiles. Virulence assessments using E . piscicida representatives from each MLSA group resulted in 14‐day cumulative mortality ranging from 22% to 54% and 63 to 72% in channel and hybrid fingerlings, respectively. Across all phylogroups, mortality was higher in hybrid catfish ( p < .05), supporting previous work indicating E . piscicida is an emerging threat to hybrid catfish aquaculture in the south‐eastern United States.