ARS | Publication request: Spleen size and plasma levels of mannose binding lectin in channel catfish Ictalurus punctatus families exhibiting different susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: September 2, 2011
Publication Date: February 1, 2012
Citation: Peterson, B.C., Booth, N.J., Ourth, D.D., Shoemaker, C.A., Lafrentz, B.R. 2012. Spleen size and plasma levels of mannose binding lectin in channel catfish Ictalurus punctatus families exhibiting different susceptibilities to Flavobacterium columnare and Edwardsiella ictaluri. Aquaculture America Conference. P. 367.

Technical Abstract: Two major problems in the channel catfish (Ictalurus punctatus) aquaculture industry have been high disease losses to enteric septicemia of catfish (ESC), caused by the bacterium Edwardsiella ictaluri and columnaris disease, caused by the bacterium Flavobacterium columnare. Methods to control these diseases include antibiotic therapy, vaccinations, and management strategies such as taking the fish off feed. Another approach to control these diseases may include selective breeding. The objectives of this study were to determine if (1) there is a correlation between susceptibility to ESC and columnaris disease and (2) to determine if spleen index and plasma levels of mannose binding lectin (MBL) are predictive indicators of susceptibility to these pathogens. Four families of channel catfish were used in this study and all were from the USDA103 strain. Family A was randomly selected from approximately 125 spawns. The remaining three families were offspring of fish that were previously challenged with E. ictaluri. The selected parents survived an in vivo E. ictaluri challenge and demonstrated mortality of less than 10%. These families are denoted family B, C, and D. Family D exhibited the highest mortality after challenge with E. ictaluri while mortality was similar among families A, B, and C. When challenged with F. columnare, family D exhibited the lowest mortality compared to families A, B, and C. Spleen index and MBL levels in unchallenged fish were similar among all families. Results of this study demonstrate that it is difficult to make improvement in resistance to E. ictaluri after one generation of selection. Although further research on a larger number of families is needed, the data suggests that fish that are more susceptible to ESC are less susceptible to columnaris disease. Spleen index and MBL levels do not appear to be predictive indicators of disease susceptibility for both bacterial pathogens.