Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract Only
Publication Acceptance Date: April 9, 2003
Publication Date: April 21, 2003
Citation: SHOEMAKER, C.A., KLESIUS, P.H., EVANS, J.J., ARIAS, C.R. MODIFIED LIVE VACCINES AGAINST EDWARDSIELLA ICTALURI AND FLAVOBACTERIUM COLUMNARE. ANNUAL EASTERN FISH HEALTH WORKSHOP. 2003. Technical Abstract: Edwardsiella ictalaluri and Flavobacterium columnare are the two most important pathogens in the channel catfish industry in the United States and are responsible for $60-80 million in annual losses. Development of vaccines against Enteric Septecemia of Catfish (ESC) and columnaris required the vaccines to be safe and easily administered to young fish. Further, the vaccine is needed to stimulate protective immunity of long duration. We developed a modified E. ictaluri isolate (RE-33) and F. columnare isolate that was attenuated and did not cause disease. In vivo reversion to virulence studies demonstrated that both vaccines were safe. Safety of the E. ictaluri vaccine on commercial farms was demonstrated in over 2.2 million catfish used in State veterinarian (Alabama and Mississippi) and USDA-APHIS approved field trials in 1997. Field safety is pending on the F. Columnare vaccine. Efficacy was also shown in laboratory trials to some E. ictaluri field isolates in 3-9 month old catfish with the modified live E. ictaluri (RE-33) vaccine. We demonstrated the effectiveness of the E. ictaluri vaccine in 7 to 10 day post hatch fry and eyed fish eggs (in ovo) following immersion. The live E. ictaluri RE-33 vaccine was licensed, produced and marketed in 2001 and 2002 by Intervet, Inc. as AQUAVAC-ESC'. This past year, we further characterized the E. ictaluri vaccine mutant. Immunoblot analysis of the LPS demonstrated that the vaccine mutant lacked high molecular weight bands in the LPS as compared to the parent isolate. Further characterization demonstrated that two fingerprinting techniques MIDI's fatty acid and Biolog's carbon utilization profiles discriminated between the parent and mutant E. ictaluri. AQUAVAC-ESC' is being successfully marketed and about 25% of all channel catfish fry were immunized in 2002. Efficacy of the modified live F. columnare vaccine was demonstrated in 48 days post hatch and 3 month old channel catfish. Intervet, Inc., has licensed the F. columnare vaccine from ARS and will continue the process of obtaining approval from USDA-APHIS-CVB for commercial use.