STUDY OF THE HUMORAL RESPONSE OF ATLANTIC SALMON (SALMO-SALAR L), NATURALLY INFECTED WITH AEROMONAS-SALMONICIDA SSP ACHROMOGENES

The humoral antibody response of healthy Atlantic salmon and of two gr oups of salmon, naturally infected with Aeromonas salmonicida ssp. ach romogenes, was examined in some detail. One diseased group was chronic ally infected and the other recently infected. It was found that the h umoral response of these two infected groups was quite different. The chronically infected fish showed poor specific response to the causati ve agent whereas the recently infected salmon produced strong specific antibody response. The chronically infected fish showed evidence of i ncreased unspecific response including an elevated level of natural an tibodies. The specific humoral response of the recently infected fish was primarily directed against two cell-associated antigens of the A. salmonicida ssp. achromogenes bacterium, the A-layer protein and the o -polysaccharide component of LPS. In the chronically infected fish the humoral response was primarily directed against the A-layer protein.