Morot Amandine, Lambert Christophe, Bidault Adeline, Dufour Alain, Rodrigues Sophie, Delavat François, Paillard Christine
Laboratoire de Biotechnologie et Chimie Marines, Université Bretagne Sud, EMR CNRS 6076, IUEM, 56100, Lorient, France; Univ Brest, CNRS, IRD, Ifremer, UMR 6539, LEMAR, Plouzané, France.
Univ Brest, CNRS, IRD, Ifremer, UMR 6539, LEMAR, Plouzané, France.
Fish Shellfish Immunol. 2025 Feb;157:110103. doi: 10.1016/j.fsi.2024.110103. Epub 2024 Dec 27.
The vibriosis of the European abalone, Haliotis tuberculata, is characterized by the rapidity of the infection by the pathogen Vibrio harveyi ORM4, leading to death of animals only after two days. The lethality of the pathogen is linked to the production of the type III secretion system (T3SS) and to genes regulated by quorum sensing (QS). The aim of this study was to investigate the colonization of the European abalone by both virulent and avirulent V. harveyi strains, as well as the involvement of T3SS and QS during infection. Our results emphasize the importance of gills for the bacterial establishment as the bacterial concentration of the avirulent V. harveyi strain significantly decreased from 189.3 ± 98.6 CFU/mg to 0.8 ± 0.5 CFU/mg between 24 and 48 h post-infection (hpi). In opposition, the pathogen V. harveyi ORM4 was able to maintain itself on the gills, with a concentration of 461.9 ± CFU/mg at 48 hpi, which was allowed by the production of T3SS and a functional QS. Following the infection cycle of V. harveyi ORM4 inside H. tuberculata, we also demonstrated that QS is essential for the ability of V. harveyi ORM4 to colonize the abalone hemolymph and to maintain in it. In response to the presence of V. harveyi, an increase in reactive oxygen species production was recorded, while the phagocytosis activity remained unchanged. We also highlighted the involvement of both QS and T3SS to escape the immune system activity, and that an overproduction of T3SS induced hemocyte mortality. This study provides the evidence that both T3SS and QS are essential for the establishment of V. harveyi ORM4 inside the European abalone.
欧洲鲍鱼（Haliotis tuberculata）弧菌病的特征是病原体哈维氏弧菌ORM4感染迅速，仅在两天后就会导致动物死亡。病原体的致死性与III型分泌系统（T3SS）的产生以及群体感应（QS）调控的基因有关。本研究的目的是调查强毒株和无毒株哈维氏弧菌在欧洲鲍鱼中的定殖情况，以及感染过程中T3SS和QS的作用。我们的结果强调了鳃对于细菌定殖的重要性，因为无毒株哈维氏弧菌的细菌浓度在感染后24至48小时（hpi）之间从189.3±98.6 CFU/mg显著降至0.8±0.5 CFU/mg。相反，病原体哈维氏弧菌ORM4能够在鳃上维持自身数量，在48 hpi时浓度为461.9±CFU/mg，这得益于T3SS的产生和功能性QS。在追踪哈维氏弧菌ORM4在欧洲鲍鱼体内的感染周期后，我们还证明QS对于哈维氏弧菌ORM4定殖于鲍鱼血淋巴并在其中维持的能力至关重要。响应哈维氏弧菌的存在，记录到活性氧产生增加，而吞噬活性保持不变。我们还强调了QS和T3SS在逃避免疫系统活性方面的作用，并且T3SS的过度产生会导致血细胞死亡。本研究提供了证据，证明T3SS和QS对于哈维氏弧菌ORM4在欧洲鲍鱼体内的定殖都是必不可少的。
