MICROSILICA AS ANTIGEN CARRIER AND ADJUVANT IN THE ATLANTIC SALMON (SALMO-SALAR L)

Bovine serum albumin and a glycine/HCl extract from Aeromonas salmonic ida were most effectively adsorbed to microsilica particles at pH 5.0 compared with pHs of 6.0, 7.0, 8.0 and 9.0. Atlantic salmon were immun ised by intraperitoneal injection of the glycine/HCl extract from A. s almonicida adsorbed to microsilica. Antibody titres against A. salmoni cida antigens demonstrated a prominent adjuvant effect of the microsil ica 8 weeks after immunisation compared with soluble antigens. The dur ation of the antibody response suggests that microsilica may have some depot effect. The antibody response was, however, lower than the resp onse obtained with Freund's complete adjuvant. Microsilica stimulated the respiratory burst activity in cultured Atlantic salmon head kidney macrophages. Some side effects of the microsilica were observed. Adhe sions between abdominal organs and between the organs and the peritone um were distinct. In addition, a dark greyish pigmentation at the site s of adhesion was evident. Cultured macrophages in the presence of hig h concentrations of microsilica resulted in toxic effects on the cells . (C) 1996 Academic Press Limited