51 / 2024-10-23 10:06:15

Prevention and rapid detection of visceral white spot disease of large yellow croaker

In order to quickly diagnose and prevent visceral white spot disease in large yellow croak(Larimichthys crocea), and seek a green and healthy method for the prevention and treatment of visceral white spot disease, we established a loop-mediated isothermal amplification (LAMP) assay for Pseudomonas plecoglossicida, and studied the effect of Chinese herbal medicine polysaccharides on the immune function of large yellow croak. The primers were designed based on the conserved region of the rpoD gene of Pseudomonas albicans, the reaction system was constructed, the standard curve was made, the sensitivity and specificity were tested, and the established method was applied to the detection of clinical samples. After intraperitoneal injection of polysaccharides from Chinese herbal medicine into large yellow croaker, the activities of immune enzymes and the relative expression of immune genes were measured. The results showed that: (1) When the final concentration of MgSO4 was 6mM and the reaction temperature was 64.7℃, LAMP showed a good linear relationship within 3.34×10^0-3.34×10^8 copies/reaction, and the sensitivity was up to 3.34×10^1 copies/reaction; (2) The results of specificity showed that there was no amplification curve for 12 bacteria, including Photobacterium damselae subsp. piscicida, Pseudomonas putida and Edwardsiella piscicida;(3) The visceral samples of large yellow croaker can be clinically detected, and whether large yellow croaker is affected by visceral white spot disease can be distinguished by the color change of the reagent;(4) Astragalus polysaccharides, Codonopsis ginseng polysaccharides, Angelica sinensis polysaccharides, Lycium barbarum polysaccharides and Ganoderma lucidum polysaccharides had significant positive effects on the activity of serum immunoenzymes and the expression of immune genes in spleen, head and kidney of large yellow croak. The LAMP detection method of Pseudomonas plecoglossicida established in this study has high sensitivity and specificity, and can be used for early diagnosis and quantitative detection of visceral white spot disease in large yellow croaker, which provides an effective method for early diagnosis and treatment of visceral white spot disease in large yellow croaker. Polysaccharides from Chinese herbal medicine provide basic materials for the prevention and treatment of diseases, and reduce drug residues and environmental pollution caused by the use of antibiotics.