넙치 병어에서 Photobacterium damselae subsp. damselae와 Vibrio spp.(V. anguillarum, V. splendidus, V. harveyi and V. ordalii)를 분리한 후 in vivo에서 병원성을 비교하였다. 분리균을 인위감염 한 결과, 폐사율, 혈청의 ALT, AST, cortisol 농도가 vibrio 감염구에 비하여 P. damselae 감염구에서 높게 나타났다. 또한, P. damselae 감염구에서 비특이적 면역반응인 식세포의 nitroblue tetrazolium(NBT) 반응과 혈청의 라이소자임 활성이 유의적으로 낮게 나타났다. 따라서, P. damselae는 특이적 효소인 damselysin의 분비로 높은 용혈능과 phospholipase 활성, 감염 시 내부 장기의 손상에 의한 ALT와 AST 상승, cortisol 농도의 증가로 인한 면역기능 저하가 높은 병원성을 나타낸 것으로 사료된다.
Photobacterium damselae subsp. damselae and 4 Vibrio spp, V. anguillarum, V. splendidus, V. harveyi and V. ordalii, were isolated from the diseased olive flounders, Paralichthys olivaceus. The pathogenicity of the isolates were compared to mortality, blood biochemical contents, such as alanineaminotransferase(ALT), aspatate aminotransferase(AST), and cortisol level, and non-specific immune responses, nitroblue tetrazolium (NBT) reduction of macrophages and lysozyme activities of serum. The mortalities and levels of ALT, AST and cortisol of fishes infected with P. damselae were higher than those of others but significantly low in non-specific immune responses, NBT and lysozyme activities. These results suggest that P. damsela might produce damselysin having high hemolytic and phospholipase activities, correlated with the pathogenicity. P. damsela could also make an obstruction of internal organs, following increasing in the level of ALT and AST, and depression in host immunity caused by induced high levels of cortisol.
