Submitted to: Vaccine
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/13/2006
Publication Date: 10/2/2006
Citation: Shoemaker, C.A., Klesius, P.H., Evans, J.J. 2006. Immunization of eyed channel catfish, Ictalurus punctatus, eggs with monovalent Flavobacterium columnare vaccine and bivalent F. columnare and Edwardsiella ictaluri vaccine. Vaccine. 25(2007):1126-1131. Interpretive Summary: Edwardsiella ictaluri and Flavobacterium columnare are both Gram-negative bacterial pathogens of channel catfish. Together, they account for as much as $50-70 million in annual losses to catfish producers in the United States. The Agricultural Research Service has developed, patented and transferred vaccines against both these important pathogens to a vaccine manufacturer. This study showed the safety and effectiveness of administering the two modified live vaccines at the same time to eyed egg stage (i.e., 24-48 h prior to hatching) channel catfish. This is important in that often these two pathogens occur together in the same farm pond and dual immunization in the hatchery will be a tool that can be used by catfish farmers to minimize losses to these important pathogens.
Technical Abstract: The efficacy of a modified live monovalent Flavobacterium columnare vaccine and bivalent F. columnare and Edwardsiella ictaluri vaccines were evaluated following immersion vaccination of eyed channel catfish (Ictalurus punctatus) eggs. The modified live F. columnare vaccine was grown in modified Shieh broth and administered at 1.35 X 10 to the 7th CFU/ml for 15 min exposure (one liter water). Booster immunization was conducted at day 34 with 2.17 X 10 to the 7th CFU/ml for 15 min. Bivalent vaccines consisted of a 1:1 ratio of the modified live F. columnare and AQUAVAC-ESC™ vaccine for the 15 min exposure (1:l immersion bath). Non-vaccinated controls were held in 1:l water without vaccine for 15 min. Fish were challenged with F. columnare (ALG-00-530) by immersion at day 109,116, and 137 post primary immunization or E. ictaluri (AL-93-75) by immersion at day 116 (multivalent vaccine group). Efficacy of monovalent modified live F. columnare vaccine administered singly or with a booster vaccination was shown to be protective with relative percent survival (RPS) values ranging from 50.0-76.8. Some variation was seen in RPS values following bivalent immunization that ranged from 33.0-59.7 in the fish challenged with F. columnare and 44.5-66.7 in fish challenged with E. ictaluri. However, the RPS values were not statistically different. The results suggest that administration of live bivalent vaccine at the eyed egg stage is safe and elicits protection upon single pathogen challenge.