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Immunostimulatory Activities of a Decapeptide Derived from Alcaligenes faecalis FY‐3 to Crucian Carp
Author(s) -
Wang G.X.,
Li F.Y.,
Cui J.,
Wang Y.,
Liu Y.T.,
Han J.,
Lei Y.
Publication year - 2011
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.2011.02533.x
Subject(s) - crucian carp , aeromonas hydrophila , titer , alcaligenes faecalis , immune system , chemistry , microbiology and biotechnology , immunostimulant , thiobarbituric acid , strain (injury) , antibody , biology , biochemistry , enzyme , bacteria , immunology , fish <actinopterygii> , genetics , fishery , anatomy , lipid peroxidation
A strain was isolated from a soil sample collected from Weihe river in Shaanxi province (108°03′E 34°14′N), which was identified as Alcaligenes faecalis by 16S rRNA analysis. A compound M showing potent immune activity was isolated from secondary metabolites of the strain through bioassay‐guided isolation techniques. The structure of the compound M was elucidated using FT‐IR, EI‐MS, 1H NMR and 13C NMR spectra and identified as cyclo‐( l ‐Pro‐Gly)5 which was first time reported as a natural product. We evaluated the immune effects of the cyclo‐( l ‐Pro‐Gly)5 on the basis of serum lysozyme activity, bacterial agglutination titre assay, superoxide anion production and phagocytic activity assay, and they were found to be significantly increased by cyclo‐( l ‐Pro‐Gly)5. The effects of cyclo‐( l ‐Pro‐Gly)5 on immune‐related gene expression were further investigated. The outcomes of real‐time quantitative polymerase chain reaction (RQ‐PCR) proved that the transcribing level of interleukin 6β (IL‐6β) and inducible nitric oxide synthase 1β (iNOS‐1β) mRNA in the blood leucocytes have been augmented by cyclo‐( l ‐Pro‐Gly)5. The challenge experiment showed that crucian carp injected the cyclo‐( l ‐Pro‐Gly)5 had significantly ( P < 0.05) lower cumulative mortality (13.0%) compared with the control (45.4%) after infection with live Aeromonas hydrophila . These results suggested that cyclo‐( l ‐Pro‐Gly)5 is a possible immunostimulant and may strengthen the immune response and protect the heath status of crucian carp against A. hydrophila .