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Non-Specific Immune Response in Large Yellow Croaker (Larimichthys crocea) Experimentally Infected With Pseudomonas
Liangyin He1,2,3, Rongguang Zhong1, Doudou Wu1
1College of Marine Sciences, Ningde Normal University, Ningde, China.
Journal of Fish Diseases
|May 5, 2026
Summary
Pseudomonas plecoglossicida causes disease in farmed large yellow croaker (LYC). This study compared immune responses to infection via injection versus immersion, finding both routes activate innate immunity, with immersion eliciting a longer-lasting response.
Area of Science:
- Aquatic animal health
- Fish immunology
- Bacterial pathogenesis
Background:
- Pseudomonas plecoglossicida infection causes visceral white nodules disease (VWND) in large yellow croaker (LYC), leading to significant aquaculture losses.
- Understanding the innate immune response in LYC is crucial for managing VWND and developing effective aquaculture strategies.
Purpose of the Study:
- To investigate and compare the non-specific innate immune responses of LYC following infection with P. plecoglossicida via intraperitoneal (IP) injection and immersion.
- To determine the median lethal dose (LD50) for P. plecoglossicida in LYC to establish appropriate challenge levels for experimental trials.
Main Methods:
- LYC were infected with P. plecoglossicida using IP injection or immersion routes at varying pathogen concentrations.
- The median lethal dose (LD50) was calculated to guide subsequent infection experiments.
- Key indicators of innate immunity, including respiratory burst, antioxidant enzyme activities (SOD, CAT, MDA), and immune enzyme levels (ACP, ALP, LZM), were measured.
- Expression levels of inflammatory cytokines (IL-1β, TNFα1, IL-8, IL-10) were analyzed.
Main Results:
- Both IP injection and immersion routes stimulated LYC innate immune responses, including enhanced respiratory burst and antioxidant activities, and increased immune enzyme levels.
- Expression of key inflammatory cytokines (IL-1β, TNFα1, IL-8, IL-10) was significantly upregulated in infected fish compared to controls.
- The immune response in the immersion group initiated later but persisted longer than in the IP injection group.
Conclusions:
- P. plecoglossicida infection triggers a robust innate immune response in LYC, involving enzymatic activities and cytokine upregulation.
- The route of infection influences the kinetics of the immune response, with immersion leading to a more prolonged activation.
- These findings enhance understanding of LYC pathogenesis and host defense, informing strategies for controlling VWND in aquaculture.
