Localization of purified surface molecules (lipopolysaccharide and A-protein) from Aeromonas salmonicida in the kidney and spleen from Atlantic salmon, Salmo salar L.

Lipopolysaccharide (LPS) and A-layer protein purified from Aeromonas salmon icida were administered intravenously in Atlantic salmon, Salmo salar L., e ither alone or in combination. Tissues from each organ were examined by imm unohistochemical techniques, using a polyclonal antiserum against A-protein and a monoclonal antibody against LPS. When given simultaneously, the anti gens seemed to be taken up by different cells in both the head and trunk ki dney. The most striking finding was that A-protein was located in epithelia l cells in renal proximal tubules, in contrast to LPS, which was not detect ed in this location. The amount of A-protein in the tissue increased with t ime until 2 h after injection. Autoradiography of SDS polyacrylamide gel el ectrophoresis of head kidney homogenates showed that in vivo processing of A-protein coupled to iodinated tyramine cellobiose (I-125-TC-A-protein) was completed within 24 h, in contrast to LPS, which was maintained in tissues . The findings of the present study suggest that cells of the head kidney o f Atlantic salmon are capable of taking up and processing the A-protein.