EFFICACY OF A LIVE CRYPTOBIA-SALMOSITICA VACCINE, AND THE MECHANISM OF PROTECTION IN VACCINATED RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, AGAINSTCRYPTOBIOSIS
S. Li et Ptk. Woo, EFFICACY OF A LIVE CRYPTOBIA-SALMOSITICA VACCINE, AND THE MECHANISM OF PROTECTION IN VACCINATED RAINBOW-TROUT, ONCORHYNCHUS-MYKISS, AGAINSTCRYPTOBIOSIS, Veterinary immunology and immunopathology, 48(3-4), 1995, pp. 343-353
An attenuated strain of Cryptobia salmositica was used as a live vacci
ne to protect rainbow trout, Oncorhynchus mykiss, against cryptobiosis
. Fish immunized with 1.0 X 10(4) or 5.5 X 10(4) attenuated C. salmosi
tica per fish were protected 3 weeks after immunization; however, this
period was reduced to 2 weeks if fish were vaccinated with 1.0 X 10(5
) attenuated parasites per fish. Fish were still protected at 6, 12 an
d 24 months after vaccination. Complement fixing antibodies in the blo
od of immunized fish lysed C. salmositica under in vitro conditions. T
he titre of complement fixing antibodies in vaccinated fish increased
rapidly 1-2 weeks post-challenge. In vitro phagocytosis was enhanced b
y antiserum and by activated macrophages from vaccinated fish. There w
as also evidence of antibody independent and antibody dependent cell-m
ediated cytotoxicity in vaccinated fish.