ABSTRACT
Individually tagged rainbow trout representing 15 full-sibling families were sequentially challenged twice with Aeromonas salmonicida causing furunculosis: first as cohabitation and then as injected intraperitoneally. The bleeding procedure prior to challenges caused the outbreak of cold water disease by Flavobacterium psychrophilum. Before and after the outbreak and challenges, 11 immunological parameters were measured from blood samples. The immunological responses predicted the fate of the fish since nearly all the initial responses were lower in individuals which later died from cold water disease than in survivors. Fish died from furunculosis had impaired respiratory burst (RB) response to A. salmonicida. Fish that had initially the highest responses survived in the outbreak and challenges. The outbreak and challenges resulted in these individuals higher and faster responses compared with initial values. Unlike in mammals, the number of monocytes, but not that of granulocytes, in rainbow trout blood correlated well with the whole blood RB activity. The fish families differed markedly from each other in capacity to resist the induced diseases.
Subject(s)
Aeromonas salmonicida , Fish Diseases/immunology , Flavobacteriaceae Infections/veterinary , Flavobacterium , Gram-Negative Bacterial Infections/veterinary , Oncorhynchus mykiss/microbiology , Animals , Complement System Proteins/immunology , Disease Resistance , Fish Diseases/mortality , Flavobacteriaceae Infections/immunology , Flavobacteriaceae Infections/mortality , Gram-Negative Bacterial Infections/immunology , Gram-Negative Bacterial Infections/mortality , Luminescence , PhagocytosisABSTRACT
The interaction between bacterial cells and activated complement components as a kinetic biological event is described. The bacteriolytic activity of complement in human and fish serum was assayed by measuring the decrease of bioluminescence of Escherichia coli transformed with lux genes. From the kinetic curves, the bacteriolytic CB(50)- and AB(50)-units were derived at any desired time point. It was observed that these values were irregular but decreased as a function of incubation time, and reached equal values during prolonged incubation, suggesting that the difference between the classical and alternative pathway activity is kinetic. From the kinetic curves, entirely new parameters could be derived: rate of the activation phase, rate of killing by the lytic phase and rate of killing by the entire pathway in undiluted serum. The rates of human and fish classical pathway were about five and two times higher than those of the alternative pathway respectively.