College of Food Science and Technology, Shanghai Ocean University, Shanghai, China.
College of Fisheries and Life Science, Shanghai Ocean University, Shanghai, China.
J Invertebr Pathol. 2018 Mar;153:156-164. doi: 10.1016/j.jip.2018.02.005. Epub 2018 Feb 7.
The causative agent of shrimp AHPND was identified as specific Vibrio parahaemolyticus strains, which harbor a virulent plasmid that contains the toxic genes pirA and B (pirAB). Herein, a Vibrio bacterium was isolated from shrimp in Shanghai. This bacterium was identified as Vibrio owensii using 16S rRNA gene phylogeny, whole genome sequencing and comparative analysis. The V. owensii cells are rod-shape (1.86 ± 0.15 µm) with a single polar flagellum (4 µm). In addition, V. owensii form mauve colonies with jagged edges on CHROMagar plates. The pirAB genes on the plasmid revealed 100% sequence similarity to that of AHPND V. parahaemolyticus, and the encoded proteins were detected in the culture media. Subculture of V. owensii showed that the pirAB genes are unstable, and their loss rate is approximately 22% and reaches a dynamic equilibrium after the fifth generation. Upon immersion bioassay, the cumulative mortality of V. owensii (pirAB)-infected shrimp was up to 100% within 4 days, and typical AHPND clinical signs were observed. Approximately 10 CFU/hepatopancreas of V. owensii cells were observed in the pirAB-infected shrimp based on both culture-dependent and -independent assay. Our results indicate that the expression of pirAB in the V. owensii strain is responsible for AHPND.
虾 AHPND 的病原体已被确认为特定的副溶血性弧菌菌株，这些菌株携带有含有毒性基因 pirA 和 B（pirAB）的毒力质粒。在此，从上海的虾中分离到了一种弧菌。该细菌通过 16S rRNA 基因系统发育、全基因组测序和比较分析，被鉴定为欧文氏弧菌。V. owensii 细胞呈杆状（1.86±0.15μm），具有单个极鞭毛（4μm）。此外，V. owensii 在 CHROMagar 平板上形成边缘锯齿状的淡紫色菌落。质粒上的 pirAB 基因与 AHPND 副溶血性弧菌的序列完全相同，并且在培养基中检测到了编码蛋白。V. owensii 的传代培养表明，pirAB 基因不稳定，其丢失率约为 22%，并在第五代后达到动态平衡。在浸泡生物测定中，感染 pirAB 的 V. owensii 虾的累积死亡率在 4 天内达到 100%，并观察到典型的 AHPND 临床症状。基于培养依赖和非依赖的检测方法，在感染 pirAB 的虾中观察到约 10 CFU/肝胰腺的 V. owensii 细胞。我们的结果表明，V. owensii 株中 pirAB 的表达是导致 AHPND 的原因。
