A Study on Serotyping of Cytophaga psychrophila Isolated from Fishes in Japan.

Abstract

The serological characteristics of the strains of C. psychrophila isolated from different fishes in different areas were compared by the microtitre method. Included were 3 strains from coho salmon ( Oncorhynchus kisutch) in Miyagi Prefecture, 4 from rainbow trout in Nagano and Tokyo Pref., 6 from ayu ( Plecoglossus altivelis) in Tokushima and Wakayama Pref. In addition to these Japanese strains, 3 strains from coho salmon in {USA} were used as reference strains. Three antisera were prepared with the type strain {NCMB1947} from coho salmon in {USA}, {FPC828} from coho salmon in Miyagi, and {FPC840} from ayu in Tokushima. In the comparison of C. psychrophila strains by using these antisera, all were positively agglutinated by each of the antisera, indicating the presence of common antigen(s). On the basis of the absorption analysis with thermostable antigens, two distinct serotypes (O-1 and O-2) were recognized. The strains from coho salmon in Japan and {USA} belonged to serotype O-1. Serotype 0-2 occurred only in Japan, and was distributed among rainbow trout as well as ayu. C. psychrophila に対する家兎抗血清を宮城県のギンザケ由来株 FPC828 と徳島県のアユ由来株 FPC840 を用いて作製し, マイクロタイター法により供試菌株との凝集反応を行った. 吸収試験の結果, 共通抗原のほかに特異抗原の存在が認められたので, 各地から収集した菌株の加熱菌体（105℃, 30分）について血清型を調べた. 日本のギンザケ由来菌株と米国のギンザケ由来菌株は同じ血清型（O-1）であり, アユ由来菌株およびニジマス由来菌株はそれとは別の血清型（O-2）であることがわかった.