Kesarcodi-Watson Aditya, Kaspar Heinrich, Lategan M Josie, Gibson Lewis F
Cawthron Institute, Private Bag 2, Nelson 7010, New Zealand.
Dis Aquat Organ. 2009 Sep 7;86(1):15-20. doi: 10.3354/dao02100.
Bacterial diseases remain a large problem in aquaculture hatcheries. The successful design and implementation of protective measures in the hatchery depends on an understanding of the dynamics of the infection process. Developing an in situ experimental protocol for pathogen challenge is therefore of paramount importance. Here, we demonstrated the minimum effective pathogenic dose (MEPD) of Vibrio splendidus (10(5) CFU ml(-1)) and a Vibrio coralliilyticus/neptunius-like isolate, Vibrio sp. DO1 (10(6) CFU ml(-1)), for New Zealand Greenshell mussel (GSM, Perna canaliculus) larvae during hatchery production. In a flow-through water hatchery system, larvae given 1 to 2 h of static water exposure to these pathogen doses showed respective average cumulative mortalities of 58 and 69% on the fourth day following pathogen exposure. After the 1 to 2 h static exposure, larvae were returned to flow-through water. Larvae exposed to a dosage one order of magnitude greater than the MEPD had higher mortalities of 73 and 96% for V. splendidus and Vibrio sp. DO1 respectively. These 4 levels of mortality were significantly greater than those of the non-exposed control larvae which respectively averaged 23 and 35% in experiments involving V. splendidus and Vibrio sp. DO1. Experiments were repeated 4 times to confirm reproducibility. After pathogen exposure, pathogens were detected in the larvae and tank water of treatments with dosages of > or =10(5) CFU ml(-1) (V. splendidus) and 10(6) CFU ml(-1) (Vibrio sp. DO1), but not in treatments with lower pathogen dosages. The challenge protocols are reproducible and provide an opportunity to assess measures for the protection of GSM larvae against infection in the hatchery environment.
细菌性疾病在水产养殖孵化场中仍然是一个大问题。在孵化场成功设计和实施保护措施取决于对感染过程动态的理解。因此，制定原位病原体攻击实验方案至关重要。在此，我们展示了灿烂弧菌（10⁵ CFU/ml）和一种溶珊瑚弧菌/海神弧菌样分离株——弧菌属DO1（10⁶ CFU/ml）对新西兰绿唇贻贝（GSM，Perna canaliculus）幼虫在孵化场生产期间的最小有效致病剂量（MEPD）。在流水孵化场系统中，让幼虫在静水中接触这些病原体剂量1至2小时，在接触病原体后的第四天，平均累积死亡率分别为58%和69%。在1至2小时的静态暴露后，幼虫被放回流水环境中。暴露于比MEPD高一个数量级剂量的幼虫，灿烂弧菌和弧菌属DO1的死亡率分别更高，为73%和96%。这4个死亡率水平显著高于未暴露的对照幼虫，在涉及灿烂弧菌和弧菌属DO1的实验中，对照幼虫的平均死亡率分别为23%和35%。实验重复进行4次以确认可重复性。病原体暴露后，在剂量≥10⁵ CFU/ml（灿烂弧菌）和10⁶ CFU/ml（弧菌属DO1）处理的幼虫和养殖池水中检测到病原体，但在较低病原体剂量处理中未检测到。这些攻击方案具有可重复性，并为评估保护GSM幼虫在孵化场环境中免受感染的措施提供了机会。
