muramidase and Actinomycetales-Infections

The objectives of this study were: 1) to investigate whether recombinant channel catfish lysozyme-g (CC-Lys-g) produced in Escherichia coli expression system possesses any lysozyme activity; and 2) to evaluate whether channel catfish lysozyme-g plasmid DNA could be used as an immunostimulant to protect channel catfish against Aeromonas hydrophila infection. Recombinant CC-Lys-g produced in E. coli expression system exhibited significant (P < 0.05) lytic activity against Gram-positive Micrococcus lysodeikticus and Gram-negative A. hydrophila. When pcDNA3.2-vectored recombinant channel catfish lysozyme-g (pcDNA-Lys-g) was transfected in channel catfish gill cells G1B, the over-expression of pcDNA-Lys-g offered significant (P < 0.05) protection to G1B cells against A. hydrophila infection. When channel catfish were intraperitoneally injected with pcDNA-Lys-g along with an adjuvant QCDCR, the transcriptional level of Lys-g was significantly (P < 0.05) increased. When pcDNA-Lys-g injected fish was challenged with a highly virulent A. hydrophila strain AL-09-71, pcDNA-Lys-g offered 100% protection to channel catfish at two days post DNA injection. Macrophages of fish injected with pcDNA-Lys-g produced significantly (P < 0.05) higher amounts of reactive oxygen species and nitric oxide than that of fish injected with pcDNA vector alone at two days post DNA injection. Taken together, our results suggest that pcDNA-Lys-g could be used as a novel immunostimulant to offer immediate protection to channel catfish against A. hydrophila infection.

Topics: Actinomycetales Infections; Adjuvants, Immunologic; Aeromonas hydrophila; Amino Acid Sequence; Animals; Cloning, Molecular; DNA, Complementary; Escherichia coli; Fish Diseases; Fish Proteins; Gram-Negative Bacterial Infections; Ictaluridae; Micrococcus; Molecular Sequence Data; Muramidase; Phylogeny; Plasmids; Real-Time Polymerase Chain Reaction; Recombinant Proteins; RNA, Messenger; Sequence Alignment

The impact of agrichemicals on aquatic vertebrate species has been a matter of increasing concern to researchers and environmentalist. In the present study, we evaluated the effects of a sublethal concentration of atrazine (10% of the LC(50-96 h)), a world-wide used herbicide, on the innate immune system of silver catfish (Rhamdia quelen). A significant reduction on phagocytic index, bacteria agglutination and bactericidal activity of the serum, serum lysozyme and total serum peroxidase activity was observed in fish exposed to atrazine for 24 h. After 10 days exposure to atrazine, only bactericidal activity of the serum, bacteria agglutination and total serum peroxidase activity were significantly reduced. Atrazine had no effect on the natural complement hemolytic activity. Our results demonstrate that atrazine decreases the innate immune response of fingerlings, which might increase its susceptibility to opportunistic pathogens.

Topics: Actinomycetales Infections; Aeromonas hydrophila; Animals; Aquaculture; Atrazine; Catfishes; Complement Hemolytic Activity Assay; Dose-Response Relationship, Drug; Female; Fish Diseases; Gram-Negative Bacterial Infections; Herbicides; Immunity, Innate; Male; Micrococcus luteus; Muramidase; Peroxidase; Water Pollutants, Chemical

Nutritional fatty acids are known to have an impact on membrane lipid composition of body cells, including cells of the immune system, thus providing a link between dietary fatty acid uptake, inflammation and immunity. In this study we reveal the significance of macrophage membrane lipid composition on gene expression and cytokine synthesis thereby highlighting signal transduction processes, macrophage activation as well as macrophage defense mechanisms. Using RAW264.7 macrophages as a model system, we identified polyunsaturated fatty acids (PUFA) of both the n-3 and the n-6 family to down-regulate the synthesis of: (i) the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α; (ii) the co-stimulatory molecule CD86; as well as (iii) the antimicrobial polypeptide lysozyme. The action of the fatty acids partially depended on the activation status of the macrophages. It is particularly important to note that the anti-inflammatory action of the PUFA could also be seen in case of infection of RAW264.7 with viable microorganisms of the genera R. equi and P. aeruginosa. In summary, our data provide strong evidence that PUFA from both the n-3 and the n-6 family down-regulate inflammation processes in context of chronic infections caused by persistent pathogens.

Topics: Actinomycetales Infections; Animals; B7-2 Antigen; Cell Line; Dietary Fats; Down-Regulation; Fatty Acids, Unsaturated; Immunity, Innate; Inflammation; Interleukin-1beta; Interleukin-6; Macrophage Activation; Macrophages; Membrane Lipids; Mice; Muramidase; Myeloid Differentiation Factor 88; Pseudomonas aeruginosa; Pseudomonas Infections; Rhodococcus equi; Tumor Necrosis Factor-alpha

The effects of unmethylated CpG oligodeoxynucleotides (ODN) on the mammalian immune system are relatively well studied but much less is known of their effects on the immune systems of different fish species. Here we show that CpG ODNs significantly enhance the survival of rainbow trout (Oncorhynchus mykiss) following bacterial challenge when used both as stand-alone prophylactic agents, or as adjuvants to a commercially available vaccine. They are also capable of increasing serum lysozyme activity in vivo and stimulating the production of chemoattractant factors for rainbow trout head kidney (HK) leucocytes in vitro.

Topics: Actinomycetales Infections; Adjuvants, Immunologic; Aeromonas salmonicida; Animals; Anti-Bacterial Agents; Blood Bactericidal Activity; Chemotaxis; Fish Diseases; Macrophages; Muramidase; Oligodeoxyribonucleotides; Oncorhynchus mykiss; Survival Analysis; Time Factors; Up-Regulation