Shoemaker C A, LaFrentz B R
Aquatic Animal Health Research Unit, United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Auburn, AL, USA.
J Fish Dis. 2015 May;38(5):491-8. doi: 10.1111/jfd.12262. Epub 2014 Jun 9.
Columnaris disease can be problematic in tilapia (Oreochromis spp.) production. An understanding of the pathogenesis and virulence of Flavobacterium columnare is needed to develop prevention strategies. The objective of this study was to determine the virulence of genetically defined isolates of F. columnare in sex-reversed hybrid tilapia, Oreochromis niloticus (L.)×O. aureus (Steindachner). A series of immersion challenge trials were performed using isolates of the five established genomovars of F. columnare: I, II, II-B, III and I/II. The mean per cent mortality of fish challenged with genomovar I, II and III isolates ranged from 0 to 100, 3.3-78 and 3.3-75%, respectively. The mean per cent mortality of fish challenged with genomovar II-B ranged from 35 to 96.7%, and the only genomovar I/II isolate tested caused no mortality. Contrary to previous work in other fish species, there did not appear to be an association between F. columnare genomovar and virulence in tilapia. The challenge model used resulted in acute mortality. An alternative challenge model was tested by cohabitating healthy fish with dead fish infected with F. columnare. This method resulted in rapid appearance of clinical signs and mortality, suggesting the potential for F. columnare to increase in virulence upon growth on/in a fish host.
柱状病在罗非鱼（尼罗罗非鱼属）养殖中可能会成为问题。为了制定预防策略，需要了解柱状黄杆菌的发病机制和毒力。本研究的目的是确定在性别反转的杂交罗非鱼尼罗罗非鱼（L.）×奥利亚罗非鱼（Steindachner）中，基因明确的柱状黄杆菌分离株的毒力。使用柱状黄杆菌已确定的五个基因组变种的分离株进行了一系列浸浴攻毒试验：I、II、II-B、III和I/II。用基因组变种I、II和III分离株攻毒的鱼的平均死亡率分别为0至100%、3.3%至78%和3.3%至75%；用基因组变种II-B分离株攻毒的鱼的平均死亡率为35%至96.7%，而测试的唯一基因组变种I/II分离株未导致死亡。与之前在其他鱼类中的研究结果相反，在罗非鱼中，柱状黄杆菌基因组变种与毒力之间似乎没有关联。所使用的攻毒模型导致急性死亡。通过将健康鱼与感染柱状黄杆菌的死鱼同居来测试另一种攻毒模型。这种方法导致临床症状和死亡迅速出现，表明柱状黄杆菌在鱼宿主上生长时毒力可能会增强。
