Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada; Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, C1A 4P3, Canada.
Department of Biology, University of Waterloo, Waterloo, ON, N2L 3G1, Canada; Faculty of Veterinary Medicine and Zootechnics, Universidad Peruana Cayetano Heredia, Lima, Peru.
Fish Shellfish Immunol. 2024 Aug;151:109742. doi: 10.1016/j.fsi.2024.109742. Epub 2024 Jul 2.
Rainbow trout is an important fish species for Peruvian artisanal aquaculture, comprising over 60 % of the total aquaculture production. However, their industry has been highly affected by several bacterial agents such as Yersinia ruckeri. This pathogen is the causative agent of Enteric Redmouth Disease, and causes high mortality in fingerlings and chronic infection in adult rainbow trout. To date, the immune response of rainbow trout against Y. ruckeri has been well studied in laboratory-controlled infection studies (i.e. intraperitoneal infection, bath immersion), however, the immune response during natural infection has not been explored. To address this, in this study, 35 clinically healthy O. mykiss without evidence of lesions or changes in behavior and 32 rainbow trout naturally infected by Y. ruckeri, were collected from semi-intensive fish farms located in the Central Highlands of Peru. To evaluate the effect on the immune response, RT-qPCR, western blotting, and ELISA were conducted using head kidney, spleen, and skin tissues to evaluate the relative gene expression and protein levels. Our results show a significant increase in the expression of the pro-inflammatory cytokines il1b, tnfa, and il6, as well as ifng in all three tissues, as well as increases in IL-1β and IFN-γ protein levels. The endogenous pathway of antigen presentation showed to play a key role in defense against Y. ruckeri, due to the upregulation of mhc-I, tapasin, and b2m transcripts, and the significant increase of Tapasin protein levels in infected rainbow trout. None of the genes associated with the exogenous pathway of antigen presentation showed a significant increase in infected fish, suggesting that this pathway is not involved in the response against this intracellular pathogen. Finally, the transcripts of immunoglobulins IgM and IgT did not show a modulation, nor were the protein levels evaluated in this study.
虹鳟是秘鲁水产养殖的重要鱼类，其总产量超过 60%。然而，该产业受到多种细菌病原体的严重影响，如鲁氏耶尔森氏菌。该病原体是肠型红嘴病的致病因子，会导致鱼苗高死亡率和成年虹鳟慢性感染。迄今为止，虹鳟对 Y. ruckeri 的免疫反应已在实验室控制的感染研究（即腹腔内感染、浸泡浴）中得到了很好的研究，但尚未探索自然感染期间的免疫反应。为了解决这个问题，在这项研究中，从秘鲁中海拔的半集约化养殖场收集了 35 条没有病变或行为变化迹象的临床健康 O. mykiss 和 32 条自然感染 Y. ruckeri 的虹鳟。为了评估对免疫反应的影响，使用头肾、脾脏和皮肤组织进行 RT-qPCR、western blot 和 ELISA，以评估相对基因表达和蛋白水平。我们的结果表明，所有三种组织中的促炎细胞因子 il1b、tnfa 和 il6 以及 ifng 的表达均显著增加，IL-1β 和 IFN-γ 蛋白水平也增加。抗原呈递的内源性途径由于 MHC-I、tapasin 和 b2m 转录物的上调以及感染虹鳟中 Tapasin 蛋白水平的显著增加，在防御 Y. ruckeri 方面发挥了关键作用。与抗原呈递的外源性途径相关的基因均未显示感染鱼的显著增加，表明该途径不参与针对这种细胞内病原体的反应。最后，免疫球蛋白 IgM 和 IgT 的转录物未显示调节，本研究也未评估其蛋白水平。
