A COMPARISON OF IMMERSION, IMMERSION ORAL COMBINATION AND INJECTION METHODS FOR THE VACCINATION OF CHANNEL CATFISH ICTALURUS-PUNCTATUS AGAINST EDWARDSIELLA-ICTALURI/

Four different vaccination regimes, including non-vaccinated controls (C), immersion/oral combination (IO), late immersion (LI), and injecti on (IJ), were evaluated for antibody production and protection from ch allenge in channel catfish Ictalurus punctatus that were hatched and r aised in recirculating culture systems over a 28-wk period. For IO, fr y were vaccinated by immersion on day 12 post-hatch and given an oral booster during week 10 post-hatch. The LI and IJ delivered vaccine was also administered at week 10 post-hatch. No titers were detected in t he IO group prior to the oral booster at week 10. Mean titers rose sha rply after the week 10 vaccinations in all treatment groups, maintaine d a high level for about 8 wk, and slowly declined over the next 4 wk. Injected fish had significantly higher titers during the primary resp onse period than either LI or IO fish. There was no statistical differ ence in titers between LI and IO fish during the primary response. Aft er an oral booster delivered during week 22, titers in LI and IO fish increased significantly at week 25, while titers in IJ fish declined d espite the booster delivery. An immersion booster delivered during wee k 25 resulted in significant increases in titers in all vaccinated gro ups. Of multiple challenges, the only one not marred by concurrent col umnaris infections revealed a low, but significant level of protection in IJ fish at 12 wk post vaccination.