Susceptibility of channel catfish, Ictalurus punctatus (Rafinesque), to Edwardsiella ictaluri challenge following copper sulphate exposure

Abstract

Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L(-1), were challenged with 7.5 x 10(6) colony forming units L(-1) of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure.

Evaluation of a 4-h static copper sulphate treatment against experimental infection of Flavobacterium columnare in channel catfish (Ictalurus punctatus)

“…MacFarlane, Bullock and McLaughlin (1986) reported that pre‐exposure to CuSO 4 protected against F. columnare challenge in striped bass Morone saxatilis . Griffin and Mitchell (2007) demonstrated that pre‐exposure of channel catfish to CuSO 4 afforded some protection against Edwardsiella ictaluri . Rougier, Menudier, Bosgiraud and Nicolas (1996) noted that low doses of copper, pre‐ and post‐challenge with Listeria monocytogenes were protective to zebrafish, Brachydanio rerio , while high doses of copper enhanced the challenge.…”

Effects of waterborne Cu exposure in gilthead sea bream (Sparus aurata): A proteomic approach

“…Cu is widely used in aquaculture, as an algaecide and to control outbreaks of infectious diseases in fish ponds and hatcheries [4] and this practice may strongly increase the metal concentrations into aquatic ecosystems. In this scenario, aquatic organisms may suffer from chronic exposure to Cu levels, which might be 10e50 times higher than the required concentrations [5].…”

An Overview of the Immunological Defenses in Fish Skin

“…It has long been hypothesized that observed differences in disease susceptibility between species and strains are due to the differing ability of the host to prevent pathogen attachment and entry at mucosal epithelial sites [260][261][262]. Fishes literally swim in a sea of pathogens, and the importance of mucus in fish defence is now well documented.…”