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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Comparison of serum antibody responses and host protection against parasite Ichthyophthirius multifiliis between channel catfish and channel x blue hybrid catfish

Authors
item Xu, Dehai
item Klesius, Phillip

Submitted to: Fish and Shellfish Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 27, 2013
Publication Date: February 19, 2013
Repository URL: http://handle.nal.usda.gov/10113/56375
Citation: Xu, D., Klesius, P.H. 2013. Comparison of serum antibody responses and host protection against parasite Ichthyophthirius multifiliis between channel catfish and channel x blue hybrid catfish. Fish and Shellfish Immunology. 39:1356-1359.

Interpretive Summary: The CB hybrid catfish (female channel catfish × male blue catfish) has been reported to exhibit many commercially desirable characteristics, including faster growth, better feed conversion, low oxygen tolerance and resistance to some diseases. There is limited information available on the immune protection of CB hybrid against Ich. In this study, we compared immune response and host protection between channel catfish and CB hybrid catfish using a cohabitation model. Channel catfish and CB hybrid catfish were put in the same tanks and subjected to the same treatment, including vaccination methods, parasite challenge concentration, infection duration, water quality, and feeding to evaluate fish immune protection against the parasite. The immunized channel catfish and CB hybrid catfish showed a significantly higher anti-Ich antibody (titer > 3800) compared to non-immunized controls (titer < 40). After being challenged with live theronts, the immunized channel catfish and CB hybrid catfish were not infected or were infected with a low number of the parasites (< 50 trophonts per fish). The immunized fish showed a significantly higher survival (90-100%) than non-immunized controls (0%). There was no statistical difference (p > 0.05) on anti-Ich antibody titers, parasite infection and fish survival between immunized channel catfish and CB hybrid catfish. Overall results indicated that CB hybrid catfish could develop the same strong immune protection against Ich as its parent channel catfish. These study results will help fish farmers and fish breeders to select disease resistant fish to minimize the impact of disease on cultured fish.

Technical Abstract: There is limited information available on the immune protection of CB hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish I. furcatus) against the fish parasite Ichthyophthirius multifiliis (Ich). The objective of this study was to compare immune response and host protection between channel catfish and CB hybrid catfish using a cohabitation model. Channel catfish and CB hybrid catfish were immunized with live theronts by immersion or by IP injection at the dose of 10,000-20,000 theronts per fish in two trials. The fish were then challenged with theronts to compare fish immune protection against the parasite between channel catfish and CB hybrid catfish. The immunized channel catfish and CB hybrid catfish showed a significantly higher (p < 0.05) serum anti-Ich antibody (immobilization titer > 3800) comparing to non-immunized controls (immobilization titer < 40). After being challenged with live theronts, the immunized channel catfish and CB hybrid catfish had none or a low number of the parasites (< 50 trophonts per fish) and showed a significantly higher survival (90-100%) than non-immunized controls (0%). There was no statistical difference (p > 0.05) on anti-Ich antibody, parasite infection and fish survival between immunized channel catfish and CB hybrid catfish. Overall results indicated that CB hybrid catfish could develop the same strong immune protection against Ich as its parent channel catfish.

Last Modified: 9/22/2014
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