The fate of Pseudomonas anguilliseptica in Artificially Infected Eels Anguilla japonica
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赤点病原因菌Pseudomonas anguillisepticaの病原株(K+血清型)をニホンウナギに水温12℃～20℃下で致死量接種した場合, 血液および各組織内の生菌数は, 接種後一時的に減少したが, その後急激に増加し, 瀕死魚ではいずれの組織においても108～1010CFU/ml or gに達した。一方, 致死量以下の接種または水温28℃で致死量接種した場合, あるいは非病原株(K-血清型)を接種した場合, 菌は接種した筋肉部を除きいずれも3日以内に魚体内から消失した。
The multiplication and distribution of Pseudomonas anguilliseptica in artificially infected Japanese eels were studied by viable cell count.
When the eels were injected intramuscularly with the lethal doses (10^7, 10^9/100 g fish weight) of a K antigen-possessing virulent strain at 12°C or 20°C, the viable cell numbers in blood and tissues decreased from 1 h to 12 h post-inoculation. This phase was followed by a static phase, in which the organism persisted at lower concentration or grew slowly, and the duration of this phase depended on the inoculated dosage and ambient water temperature. At the final phase, the organism appeared in rapidly increasing number and rose to high levels (10^8-10 viable cells/g or ml), which persisted until the death of fish.
On the contrary, when inoculated with sublethal dose (10^5 CFU) of the virulent strain, with lethal dose of virulent strain at a higher water temperature (28°C), or with a dose of a K antigen-lacking avirulent strain, the organism disappeared completely from the tissues except the muscle of the inoculated site within 1-3 days.
The final level of viable cell count in the moribund eels was higher than those of Aeromonas hydrophila or Vibrio anguillarum, and this difference was thought to reflect toxin production.
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Copyright (c) 1985 The Japanese Society of Fish Pathology
Graduate School of Biosphere Science