ARS | Publication request: DEVELOPMENT OF AN INDIRECT ELISA TO DETECT HUMORAL RESPONSE TO FLAVOBACTERIUM COLUMNARE INFECTION OF CHANNEL CATFISH, ICTALURUS PUNCTATUS (RAFINESQUE)

Submitted to: Journal of Applied Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 17, 2002
Publication Date: January 1, 2003
Citation: Shoemaker, C.A., Shelby, R.A., Klesius, P.H. 2003. Development of an indirect elisa to detect humoral response to Flavobacterium columnare infection of channel catfish, Ictalurus punctatus (Rafinesque). Journal of Applied Aquaculture. 14:43-52.

Interpretive Summary: Columnaris disease caused by a long gram negative bacteria (Flavobacterium columnare) has been suggested as the second most important disease of cultured catfish. Presently, little is known about the immune response of catfish to this important pathogen and no method is available to measure antibody against this bacterial infection in catfish. We developed a rapid test to detect antibodies in the blood of catfish to F. columnare. With a small sample of blood, we can determine if the fish was exposed to the bacteria in about two hours. This assay will allow for monitoring of the catfish's immune response (antibody) to F. columnare following natural exposure or vaccination against this bacteria. The test will also allow researchers to study the importance of antibody to columnaris disease in channel catfish.

Technical Abstract: The humoral antibody response of channel catfish, Ictalurus punctatus, to experimental Flavobacterium columnare infection was measured in control (non-infected) and infected (intraperitoneal- and intramuscular-injected) fish by an indirect enzyme-linked immunoassay (ELISA). The antibody response of the experimentally infected fish was significantly higher (P < 0.0001) than that of the non-infected channel catfish by both indirect ELISA and agglutination. The indirect ELISA utilized goat anti-channel catfish IgM and a commercially available rabbit anti-goat IgG enzyme conjugate. The antibody response was directed against a cell-free sonicated antigen preparation derived from live whole F. columnare cells. Indirect ELISA and agglutination results correlated (r2 = 0.60) for anti-F. columnare antibody response in experimentally and non- infected fish. We were also able to correlate ELISA and agglutination results of 60 fish naturally infected with F. columnare (r2 = 0.76). Indirect ELISA will allow for rapid monitoring of humoral antibody, following natural exposure or vaccination against F. columnare, with a small sample of serum.