Nanoinjection as a tool to mimic vertical transmission of Flavobacterium psychrophilum in rainbow trout Oncorhynchus mykiss

Diseases of Aquatic Organisms

Elisabet Ekman¹  Leif Norrgren¹  Gun Åkerman¹  Lennart Balk¹ 

关键词: Flavobacterium psychrophilum;    Nanoinjection;    RTFS;    Rainbow trout;    Eggs;   

DOI  :  10.3354/dao055093

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Newly fertilised eggs of rainbow trout Oncorhynchus mykiss were nanoinjected with Flavobacterium psychrophilum in order to mimic vertical transmission. Two bacterial isolates with different elastin-degrading capacity were used. Allinfected groups (10, 100 and 1000 colony forming units egg^-1) showed significantly higher cumulative mortalities than the control groups at the end of the experiment, 70 d post-hatching. The total mortalities in the control groups were below2.5%. In the high-dose groups, 95 to 100% of the eggs died during the eyed stage. In the intermediate group infected with the elastin-negative isolate, the major mortality occurred during the eyed stage of the egg, with a total cumulative mortality of 83%at the end of the experiment. In the intermediate group infected with the elastin-positive isolate, a total mortality of 63% was recorded. In this group, diseased fry showed clinical signs of disease and morphological changes similar to those describedin connection with rainbow trout fry syndrome (RTFS) shortly after the beginning of feeding. In the low dose groups, the mortality in the elastin-negative group was 14% and in the elastin-positive group 11%. The bacterium was isolated from dead eggs andfry in infected groups and demonstrated in internal organs of dead and moribund fry by immunohistochemistry. The nanoinjection method used in this study may be a useful method to study pathogens, like F. psychrophilum, that can be verticallytransmitted.

【 授权许可】

Unknown