Abstract
Vaccination of rainbow trout, Salmo gairdneri, by immersion and injection against strepto-coccal infection was investigated. Formalin killed cells of β-haemolytic Streptococcus sp. with and without Freund's complete adjuvant were intraperitoneally injected. The vaccination by immersion was administered by immersing the fish in formalin killed bacterin for three min.
Groups of 25 fish immunized by immersion as well as injection showed 70% or greater relative per cent survival (RPS) when challenged with live Streptococcus sp. injected intraperitoneally. Immune fish surviving challenge did not have Streptococcus sp. in the blood or kidney. Anti-Streptococcus sp. agglutination. antibody titers were low in intraperitoneally immunized fish. No detectable agglutinating antibody was demonstrated in fish vaccinated by the immersion method.
