Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2426065 | Aquaculture | 2006 | 6 Pages |
This study evaluated the potential to orally deliver a previously developed Streptococcus iniae vaccine in tilapia using Oralject™ technology. This technology was developed to administer bioactive compounds to monogastric animals, and has been shown to be effective for delivery of a variety of antigens in numerous fish species. Two different formulations containing two doses of vaccine (four treatments) were fed to tilapia (4 tanks of 25 fish each) for 1 (Oralject-1 and Oralject-2 each containing 2 × 109 cells/g of feed) day (am and pm to satiation) or 5 (Oralject-1 and -2 each containing 2 × 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, TSB) were included. Mean percent intake indicated that tilapia fed for 1 day (twice to satiation) the Oralject-1 consumed significantly (P < 0.05) more feed than fish fed Oralject-2 (4.05% vs. 3.21%, respectively). Fish fed for 5 days either commercial feed or Oralject-1 or -2 also showed differences in feed intake; on most days, fish consumed significantly less (P < 0.05) Oralject-2 (∼ 1%) than the commercial diet or Oralject-1 (∼ 2.5%). Tilapia were challenged 23 days post-vaccination by i.p. injection of 1 × 106 CFU S. iniae/fish. Mean percent mortality was 47.5 (± 7.5) in the TSB-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 and 63.1% in the most effective Oralject-vaccine-treated group. The results suggest that oral delivery of the lyophilized S. iniae vaccine using Oralject™ technology provided protection against streptococcal disease. These data validate an initial proof-of-principle for oral vaccination of tilapia using S. iniae in the Oralject™ system.