The relationship between vaccine dose and efficacy in channel catfish
Ictalurus punctatus vaccinated as fry with a live attenuated strain of
Edwardsiella ictaluri (RE-33)
D.J.
Wise, J.S. Terhune-2001
Journal
of the World Aquaculture Society, 32(2): 177-183 (from Current Contents)
Abstract :
Channel
catfish Ictalurus punctatus were vaccinated at 12 d of age (post-hatch) by a
2-min bath immersion with attenuated Edwardsiella ictaluri RE-33 at doses of
2.5 x 10(5), 2.5 x 10(6), and 2.4 x 10(7) colony-forming units CFU/mL of
water. Following vaccination, RE-33 was recovered from a greater percentage
of fry that were vaccinated at the high and intermediate doses compared to
fry vaccinated at the lowest dose. Independent of dose, the greatest
percentage of RE-33 positive fry occurred between 1 and 6 d post-vaccination
with a significant decrease in positive fry observed on day 12. A
significant increase in mortality occurred 6 to 12 d post-vaccination in fry
vaccinated at the highest dose. No differences in post-vaccination
mortalities occurred between the other treatments. Following virulent E.
ictaluri challenge, mortalities of fish vaccinated at doses of 2.5 x 10(6)
and 2.4 x 10(7) CFU/mL were significantly less than those of fish vaccinated
at 2.5 x 10(5) CFU/mL and sham-vaccinated control fish. These data show that
vaccination with RE-33 can offer protection against subsequent virulent E.
ictaluri infection.
(Thad
Cochran Natl Warmwater Aquaculture Ctr, POB 197, Stoneville, MS 38776, USA)