Immunization of eyed channel catfish,Ictalurus punctatus, eggs with monovalentFlavobacterium columnarevaccine and bivalentF. columnareandEdwardsiella ictalurivaccine

The efficacy of a modified live monovalentFlavobacterium columnarevaccine and bivalentF. columnareandEdwardsiella ictalurivaccines were evaluated following immersion vaccination of eyed channel catfish (Ictalurus punctatus) eggs. The modified liveF. columnarevaccine was grown in modified Shieh broth and administered at 1.35x107CFU/ml for 15min exposure (1l water). Booster immunization was conducted at day 34 with 2.17x107CFU/ml for 15min. Bivalent vaccines consisted of a 1:1 ratio of the modified liveF. columnareand AQUAVAC-ESC(TM) vaccine for the 15min exposure (1l immersion bath). Non-vaccinated controls were held in 1l water without vaccine for 15min. Fish were challenged withF. columnare(ALG-00-530) by immersion at days 109, 116, and 137 post-primary immunization orE. ictaluri(AL-93-75) by immersion at day 116 (bivalent vaccine group). Efficacy of monovalent modified liveF. columnarevaccine administered singly or with a booster vaccination was shown to be protective with relative percent survival (RPS) values ranging from 50.0 to 76.8. Some variation was seen in RPS values following bivalent immunization, ranging from 33.0 to 59.7 in the fish challenged withF. columnareand 44.5 to 66.7 in fish challenged withE. 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.