Jari Madetoja

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The goal of fish vaccination today is to protect fish against multiple bacterial fish pathogens simultaneously using polyvalent vaccines. However, many immunological processes such as antigenic cross-reaction, antigenic competition, affinity maturation and antigen-induced suppression may affect the specificity, avidity and level of antibodies. Consequently,(More)
Rainbow trout fry syndrome and cold-water disease are serious diseases in farmed salmonid fish. In the present study, three methods were compared, for the detection of the causative pathogen, Flavobacterium psychrophilum in water. The methods included traditional agar plate cultivation on tryptone yeast extract salts (TYES) agar, immunofluorescence antibody(More)
The infection route of Flavobacterium psychrophilum into rainbow trout Oncorhynchus mykiss was studied using bath and cohabitation challenges as well as oral challenge with live feed as a vector. Additionally, the number of bacterial cells shed by infected fish into the surrounding water was determined in the cohabitation experiment and in challenge(More)
Efficacy of mineral oil-based experimental injection vaccines against Flavobacterium psychrophilum were tested in rainbow trout, Oncorhynchus mykiss (Walbaum), under laboratory and field conditions. The vaccines consisted of formalin- or heat-inactivated whole bacterium cell preparations of two different serotypes (Fd and Th) or a combination of(More)
Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome has become a widespread fish pathogen in freshwater aquaculture worldwide. In this study, a low molecular mass fraction (P25-33), with an approximate weight of 25-33 kDa, was identified among F. psychrophilum strains in an immunoblotting analysis with anti-F. psychrophilum sera.(More)
Atypical Aeromonas salmonicida (AAS) causes generalized lethal infections in farmed Arctic charr, Salvelinus alpinus (L.), and European grayling, Thymallus thymallus (L.), and is thus a serious threat for culture of these fish species. Virulence factors were studied among isolates of AAS from Arctic charr (n = 20), European grayling (n = 19) and other fish(More)
Cultured stocks of Arctic charr Salvelinus alpinus and European grayling Thymallus thymallus are vulnerable to infection by achromogenic atypical Aeromonas salmonicida (AAS). In Finland, natural stocks of both fish species have to be supported by restocking, and AAS infection poses a threat to successful restocking because no preventive means are available.(More)
Flavobacterium psychrophilum, the causative agent of rainbow trout fry syndrome and cold water disease in salmonids, causes serious disease outbreaks in fish farms worldwide. The aim of the present study was to examine the survival capacity of F. psychrophilum in laboratory microcosms containing sterilised water under different environmental conditions and(More)
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