The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; University of Chinese Academy of Sciences, Beijing, China.
The Key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, China; University of Chinese Academy of Sciences, Beijing, China; Guangdong Laboratory Animals Monitoring Institute, Guangzhou, Guangdong, China.
Fish Shellfish Immunol. 2020 Mar;98:875-886. doi: 10.1016/j.fsi.2019.11.047. Epub 2019 Nov 18.
The susceptibility of fish from different culture environments to bacterial infection is not well known. The susceptibility and pathological changes of conventional (CV) and specific pathogen-free (SPF) rare minnow (Gobiocypris rarus) infected with two gram-negative bacteria, Flavobacterium columnare and Pseudomonas fluorescens are investigated. Rare minnows were intraperitoneally challenged with two bacterial species to first determine semi-lethal doses (LD), and then with the LD dose, determine innate immune response. Infected rare minnows developed characteristic red bellies and then died. LD doses of F. columnare and P. fluorescens were 4.586 × 10 cfu/mL and 2.319 × 10 cfu/mL for CV rare minnow, and 2.575 × 10 cfu/mL and 1.935 × 10 cfu/mL, respectively, for SPF rare minnow. The results of RT-PCR showed that the highest levels of toll-like receptor 3 (TLR3), interleukin-6 (IL-6), interferon-2 (IFN-2) and rare minnow Z-DNA binding protein kinase (GrPKZ) mRNA were noticed at 6-48 h post-infection (hpi). In addition, TLR3, IL-6 and IFN-2 in F. columnare challenged rare minnow were more highly expressed than those in P. fluorescens challenged rare minnow, whereas as opposed in the expression of GrPKZ mRNA. Stimulation of innate immune responses is closely related to bacterial virulence. SPF rare minnow might be more susceptible to these bacteria than CV rare minnow, possibly due to their clean environment and lack of resistance. We speculate that clean environment renders rare minnow more susceptible to bacterial infections.
不同养殖环境下鱼类对细菌感染的易感性尚不清楚。本研究调查了两种革兰氏阴性菌（柱状屈挠杆菌和荧光假单胞菌）感染常规（CV）和无特定病原体（SPF）稀有鲫（Gobiocypris rarus）后，常规鱼和 SPF 鱼的易感性和病理变化。先用两种细菌对稀有鲫进行腹腔注射挑战，以确定半致死剂量（LD），然后用 LD 剂量确定先天免疫反应。感染后的稀有鲫出现典型的红肚，然后死亡。CV 稀有鲫感染 F. columnare 和 P. fluorescens 的 LD 剂量分别为 4.586×10cfu/mL 和 2.319×10cfu/mL，SPF 稀有鲫的 LD 剂量分别为 2.575×10cfu/mL 和 1.935×10cfu/mL。RT-PCR 结果显示，TLR3、IL-6、IFN-2 和稀有鲫 Z-DNA 结合蛋白激酶（GrPKZ）mRNA 的水平在感染后 6-48 h 达到最高。此外，在柱状屈挠杆菌感染的稀有鲫中，TLR3、IL-6 和 IFN-2 的表达高于在荧光假单胞菌感染的稀有鲫中的表达，而 GrPKZ mRNA 的表达则相反。先天免疫反应的刺激与细菌的毒力密切相关。SPF 稀有鲫可能比 CV 稀有鲫更容易受到这些细菌的感染，这可能是由于它们所处的清洁环境和缺乏抵抗力。我们推测清洁的环境使稀有鲫更容易受到细菌感染。
