Submitted to: International Symposium of Fish Vaccinology
Publication Type: Abstract Only
Publication Acceptance Date: February 10, 2003
Publication Date: April 9, 2003
Citation: SHOEMAKER, C.A., KLESIUS, P.H., ARIAS, C.R., EVANS, J.J. A MODIFIED LIVE VACCINE AGAINST ENTERIC SEPTICEMIA IN CHANNEL CATFISH. INTERNATIONAL SYMPOSIUM OF FISH VACCINOLOGY. 2003. Technical Abstract: Edwardsiella ictaluri, the causative agent of enteric septicemia of catfish (ESC), is responsible for $60 million in annual losses to the channel catfish industry. Development of a successful vaccine against ESC required the vaccine to be safe and easily administered to young fish. Further, the vaccine needed to stimulate protective cell mediated immunity of long duration. We developed a modified E. ictaluri isolate (RE-33) that was attenuated and did not cause disease in susceptible fish. In vivo reversion to virulence studies demonstrated the vaccine was safe. Safety on commercial farms was demonstrated in over 2.2 million catfish in State veterinarian (Alabama and Mississippi) and USDA-APHIS approved field trials in 1997. Efficacy was also shown in laboratory trials to a number of E. ictaluri field isolates in 3-9 month old catfish. In 1998-1999 we demonstrated the effectiveness of the vaccine in 7 to 10 day post hatch fry following immersion. Vaccination of eyed eggs (in ovo) was recently accomplished (1999,2000). Intervet, Inc., licensed, produced, and marketed the modified live E. ictaluri RE-33 in 2000, 2001, and 2002 under the trade name AQUAVAC-ESC'. This past year, we further characterized the E. ictaluri vaccine mutant. Immunoblot analysis of the LPS demonstrated 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 were able to discriminate between the parent and mutant E. ictaluri. AQUAVAC-ESC' is being successfully marketed and used by producers of channel catfish to prevent ESC in southeastern US.