Submitted to: European Association of Fish Pathologists
Publication Type: Abstract Only
Publication Acceptance Date: 5/19/2005
Publication Date: 9/11/2005
Citation: Shoemaker, C.A., Vandenberg, G., Desormeaux, A., Klesius, P.H., Evans, J.J. 2005. Efficacy of a streptococcus iniae vaccine delivered using oralject™ technology in tilapia (oreochromis niloticus). European Association of Fish Pathologists. 12th EAFP International Conference on Diseases of Fish and Shellfish 11th – 16th September 2005 Copenhagen, Denmark. pg 101.
Technical Abstract: This study evaluated the oral delivery of a previously developed Streptococcus iniae vaccine in tilapia using Oralject™ technology. This technology was developed to administer bioactive compounds to monogastric animals. Two different formulations containing two doses of vaccine (four treatments) were fed to tilapia (4 tanks of 25 fish each) for one (Oralject A and Oralject C each containing 2 X 109 cells/g of feed) day (am and pm to satiation) or five (Oralject A and C each containing 2 X 108 cells/g of feed) days (once daily to satiation). The incorporated vaccine was a patented lyophilized modified bacterin (US Patent No. 6,379,677 B1). A positive control treatment [intraperitoneally (i.p.) injected S. iniae vaccine] and a negative control treatment (i.p. injection of tryptic soy broth) were included. Mean percent intake indicated that tilapia fed for one day (twice to satiation) the Oralject A – 2 X 109cells consumed significantly (p < 0.05) more feed than fish fed Oralject C – 2 X 109cells (4.05 vs. 3.21 %, respectively). Fish fed for 5 days either commercial feed or Oralject A or C (2 X 108 cells) also showed differences in feed intake. On most days, fish consumed significantly less (p < 0.05) Oralject C (~ 1%) than the commercial diet or Oralject A (~2.5 %). Tilapia were challenged 23 days post vaccination by i.p. injection of 1 X 106 CFU S. iniae/fish. Mean percent mortality was 47.5 (± 7.5) in the non-immunized challenged tilapia and was significantly higher (p < 0.001) than in all immunized groups. No mortality occurred in the i.p. vaccinated tilapia. Mortality ranged from 17.5 to 31.25 in the Oralject™ treatments. Relative percent survival was 100 % in the i.p. vaccinated tilapia, 63.1 % in the Oralject A-2 X 109 1 day fed tilapia, 55.3 % in the Oralject A-2 X 108 5 day fed fish, 52.6 % in the Oralject C-2 X 108 1 day fed fish and 34.2 % in the Oralject C-2 X 108 5 day treatment. The results suggest that oral delivery of lyophilized S. iniae vaccine using Oralject™ technology provided protection against streptococcal disease, however, protection achieved was less than obtained following parenteral injection.