ARS | Publication request: IN OVO VACCINATION OF CHANNEL CATFISH WITH MODIFIED LIVE EDWARDSIELLA ICTALURI VACCINES

Submitted to: European Association of Fish Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: May 22, 2001
Publication Date: September 9, 2001
Citation: SHOEMAKER, C.A., KLESIUS, P.H., EVANS, J.J. IN OVO VACCINATION OF CHANNEL CATFISH WITH MODIFIED LIVE EDWARDSIELLA ICTALURI VACCINES. TENTH INTERNATIONAL CONFERENCE "DISEASE OF FISH AND SHELLFISH" EUROPEAN ASSOCIATION OF FISH PATHOLOGISTS. 2001.

Technical Abstract: Eyed channel catfish (Ictalurus punctatus) ova (i.e., eyed eggs) were vaccinated by immersion exposure with a modified live Edwardsiella ictaluri isolate RE-33 (trial 1) or the AQUAVAC-ESC vaccine (trial 2) prior to hatching. AQUAVAC-ESC is the modified live E. ictaluri isolate (RE-33) which was licensed, produced and marketed as a vaccine against enteric septicemia of catfish by Intervet, Inc., Millsboro, Deleware. In ovo experiments were carried out in two trials where eyed eggs were either immunized alone or with booster. Fry from immunized and non- immunized eggs were challenged with virulent E. ictaluri (AL-93-75) after 33 (trial 1) or 60 (trial 2) days post immunization. Relative percent survival of single immunized fry was 87.9 in trial 1, however, data did not fit Amend's criteria of 60 % mortality in the non-immunized fish. In trial 2, mean percent mortality in the non-immunized fry (64.2+/-5.8) was significantly higher (p=0.003) than mean percent mortality in the fry immunized only as eggs or fry that received a booster immunization (25.8+/-5.1 and 46.7+/-0.8, respectively). Relative percentage survival was 59.7 in the single immunized fry and 27.3 in the booster immunized fry. The resulting low RPS from the fry immunized twice (trial 2 only) suggests that tolerance may have occurred possibly due to presence of excess antigen in relation to antigen presenting cells (i.e., macrophages) as suggested in other animals. Results of single immunization of eyed fish eggs indicates that in ovo vaccination is possible. Successful in ovo vaccination of fish eggs will allow for the earliest immunization of fish (i.e., in the hatchery).