Nature of the immune response in coho salmon Oncorhynchus kisutch following vaccination with Vibrio ordalii lipopolysaccharide by two different routes

The question as to whether immersion (= IMM) vaccination stimulates an immune response similar to that yielded by vaccination via the intraperitoneal (= IP) route was examined using Vibrio ordalii (Vo) lipopolysaccharide as immunogen and coho salmon Oncorhynchus kisutch as test fish. The experimental approach was to determine if the partially purified immunoglobulins in the plasma and mucus from coho salmon vaccinated by each of the above methods were protective to naive coho recipients. The plasma immunoglobulins from IP- and IMM-vaccinated coho protected the naive coho recipients against challenge with live Vo cells. Protection was due to Vo-specific antibodies because the protection could be removed from the transferred material by absorption with Vo cells but not with cells of a serologically unrelated fish pathogen (Renibacterium salmoninarum ). No protection was transferred with material concentrated from mucus of donors that were IP- or IMM-vaccinated. IP and IMM methods of vaccination yield a humoral (systemic) response. This response is probably the important protective response following vaccination or following natural challenges in the field.