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Immunomodulatory effect of plasma-derived Streptococcus parauberis challenged olive flounder (Paralichthys olivaceus)
E H T Thulshan Jayathilaka1, Mahanama De Zoysa1, Chamilani Nikapitiya1
1College of Veterinary Medicine and Research Institute of Veterinary Medicine, Chungnam National University, Yuseong-gu, Daejeon 34134, Republic of Korea.
Abstract:
This study investigates the transcriptomic and immunomodulatory effects of exosomes derived from Streptococcus parauberis-infected olive flounder (Paralichthys olivaceus) plasma (Sp-Exo) and their potential role in conferring disease resistance. RNA sequencing of kidneys in Sp-Exo treated olive flounder identified 21,581 genes, with 1182 showing substantial differential expression. Functional annotation revealed enrichment of immune-related pathways such as focal adhesion, PI3K-Akt, and MAPK signaling among upregulated genes, while downregulated genes were associated with cardiomyopathy-related pathways. To evaluate the immunomodulatory effects of Sp-Exo, olive flounders were intraperitoneally injected with PBS (control), Sp-Exo or PBS-Exo, followed by a challenge with S. parauberis (4.2 × 108 CFU/fish). Subsequently, qRT-PCR analysis of kidney tissues at 4 days post-challenge (dpc) revealed upregulation (>1.5-fold) of immune-related genes (TLR5a, IL1β, TNFα, and IL8) in the Sp-Exo group as compared to the controls. Furthermore, Sp-Exo treatment protected 50 % (RPS: 50 %) of the fish compared to control groups. Histopathological analysis demonstrated a reduced structural damage and inflammatory lesions in Sp-Exo-treated fish, supporting its role as a protective agent. These findings highlighted the immunomodulatory properties of Sp-Exo and its potential as a vaccine candidate for managing S. parauberis infections in olive flounder. Further elucidating of Sp-Exo internalization mechanisms in host cells could provide valuable insights into host-pathogen interactions and thereby support the development of novel prophylactic strategies for aquaculture.
Insights
Exosomes from Streptococcus parauberis-infected olive flounder plasma (Sp-Exo) activate immune responses and protect fish against bacterial infection. This suggests Sp-Exo could be a potential vaccine candidate for aquaculture.
Area of Science:
- Aquaculture immunology
- Fish disease resistance
- Exosome biology
Background:
- Streptococcus parauberis causes significant losses in olive flounder aquaculture.
- Exosomes play crucial roles in intercellular communication and immune modulation.
- Understanding host responses to bacterial infection is vital for developing effective treatments.
Purpose of the Study:
- To investigate the transcriptomic and immunomodulatory effects of exosomes from S. parauberis-infected olive flounder plasma (Sp-Exo).
- To assess the potential of Sp-Exo as a disease resistance-conferring agent in olive flounder.
- To evaluate Sp-Exo as a potential vaccine candidate against S. parauberis infections.
Main Methods:
- RNA sequencing of kidney tissues from Sp-Exo treated olive flounder.
- Functional annotation of differentially expressed genes.
- Intraperitoneal injection of olive flounder with Sp-Exo, PBS-Exo, or PBS.
- Challenge with S. parauberis.
- qRT-PCR analysis of immune-related genes.
- Histopathological examination of kidney tissues.
Main Results:
- RNA sequencing identified 1182 differentially expressed genes, enriched in immune-related pathways (focal adhesion, PI3K-Akt, MAPK signaling).
- Sp-Exo treatment upregulated key immune genes (TLR5a, IL1β, TNFα, IL8) and conferred 50% relative percent survival (RPS) against S. parauberis challenge.
- Histopathology revealed reduced inflammation and tissue damage in Sp-Exo treated fish.
Conclusions:
- Sp-Exo exhibits significant immunomodulatory properties.
- Sp-Exo demonstrates protective effects against S. parauberis infection in olive flounder.
- Sp-Exo holds promise as a novel vaccine candidate for aquaculture disease management.
