Data_Sheet_1_Population response of intestinal microbiota to acute Vibrio alginolyticus infection in half-smooth tongue sole (Cynoglossus semilaevis).XLSX

IntroductionVibriosis causes enormous economic losses of marine fish. The present study investigated the intestinal microbial response to acute infection of half-smooth tongue sole with different-dose Vibrio alginolyticus within 72 h by metagenomic sequencing.
MethodsThe inoculation amount of V. alginolyticus for the control, low-dose, moderate-dose, and high-dose groups were 0, 8.5 × 101, 8.5 × 104, and 8.5 × 107 cells/g respectively, the infected fish were farmed in an automatic seawater circulation system under a relatively stable temperature, dissolved oxygen and photoperiod, and 3 ~ 6 intestinal samples per group with high-quality DNA assay were used for metagenomics analysis.
ResultsThe acute infections with V. alginolyticus at high, medium, and low doses caused the change of different-type leukocytes at 24 h, whereas the joint action of monocytes and neutrophils to cope with the pathogen infection only occurred in the high-dose group at 72 h. The metagenomic results suggest that a high-dose V. alginolyticus infection can significantly alter the intestinal microbiota, decrease the microbial α-diversity, and increase the bacteria from Vibrio and Shewanella, including various potential pathogens at 24 h. High-abundance species of potential pathogens such as V. harveyii, V. parahaemolyticus, V. cholerae, V. vulnificus, and V. scophthalmi exhibited significant positive correlations with V. alginolyticus. The function analysis revealed that the high-dose inflection group could increase the genes closely related to pathogen infection, involved in cell motility, cell wall/ membrane/envelope biogenesis, material transport and metabolism, and the pathways of quorum sensing, biofilm formation, flagellar assembly, bacterial chemotaxis, virulence factors and antibiotic resistances mainly from Vibrios within 72 h.
DiscussionIt indicates that the half-smooth tongue sole is highly likely to be a secondary infection with intestinal potential pathogens, especially species from Vibrio and that the disease could become even more complicated because of the accumulation and transfer of antibiotic-resistance genes in intestinal bacteria during the process of V. alginolyticus intensified infection.

**引言** 弧菌病（Vibriosis）会给海水鱼类造成巨额经济损失。本研究通过宏基因组测序（metagenomic sequencing），探究了半滑舌鳎在72小时内受到不同剂量溶藻弧菌（Vibrio alginolyticus）急性感染后的肠道微生物响应。
**方法** 对照组、低剂量组、中剂量组及高剂量组的溶藻弧菌接种量分别为0、8.5×10¹、8.5×10⁴及8.5×10⁷ 个/克鱼体。感染后的养殖实验在自动海水循环系统中开展，维持相对稳定的水温、溶解氧及光照周期；每组选取3~6份经高质量DNA检测合格的肠道样本用于宏基因组学分析。
**结果** 高、中、低剂量的溶藻弧菌急性感染均在感染后24小时引发不同类型白细胞的数量变化；而单核细胞与中性粒细胞协同抵御病原体感染的现象，仅在高剂量组的72小时样本中出现。宏基因组测序结果显示，高剂量溶藻弧菌感染可在感染后24小时显著改变肠道菌群结构、降低微生物α多样性，并使弧菌属（Vibrio）和希瓦氏菌属（Shewanella）的相对丰度升高，其中包含多种潜在致病菌。哈维氏弧菌（V. harveyii）、副溶血弧菌（V. parahaemolyticus）、霍乱弧菌（V. cholerae）、创伤弧菌（V. vulnificus）以及史氏弧菌（V. scophthalmi）等潜在致病菌的高丰度物种，与溶藻弧菌均呈现显著正相关。功能分析显示，高剂量感染组在72小时内可上调与病原体感染密切相关的基因，这些基因涉及细胞运动、细胞壁/细胞膜/被膜生物合成、物质转运与代谢，以及群体感应、生物膜形成、鞭毛组装、细菌趋化性、毒力因子与抗生素抗性等通路，且相关功能主要由弧菌属细菌介导。
**讨论** 本研究结果表明，半滑舌鳎极有可能继发肠道潜在致病菌感染，尤其是弧菌属物种；且在溶藻弧菌感染加重的过程中，肠道细菌内的抗生素抗性基因积累与转移会进一步加剧疾病的复杂程度。