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Title: Recombinant goose-type lysozyme in channel catfish: Lysozyme activity and efficacy as plasmid DNA immunostimulant against Aeromonas hydrophila infection

Author
item Wei Pridgeon, Yuping
item Klesius, Phillip

Submitted to: Aquaculture America Conference
Publication Type: Proceedings
Publication Acceptance Date: 8/30/2013
Publication Date: 2/9/2014
Citation: Wei Pridgeon, Y., Klesius, P.H. 2014. Recombinant goose-type lysozyme in channel catfish: Lysozyme activity and efficacy as plasmid DNA immunostimulant against Aeromonas hydrophila infection. Proceedings Aquaculture America 2014. p. 421.

Interpretive Summary:

Technical Abstract: The objectives of this study were: 1) to investigate whether recombinant channel catfish lysozyme g (CC-Lys-g) produced in E. 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 A. hydrophila infection. Recombinant CC-Lys-g produced in Escherichia 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. Serum of catfish injected with 5 ug pcDNA-Lys-g had significantly (P <0.05) higher lysozyme activity than that of fish injected with 5 ug pcDNA vector alone (Figure 1). In addition, lysozyme activity of serum collected from fish injected with 5 ug pcDNA vector alone was significantly (P <0.05) higher than that of fish treated with TSB or QCDCR alone (Figure 1). 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.