| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4557723 | Journal of Invertebrate Pathology | 2014 | 7 Pages |
•The hemocytic MrALF can kill the G-prawn pathogen A. hydrophila but not the G+ pathogen L. garvieae.•The MrALF concentrations in prawn hemocytes and plasma are lower than the MIC and MBC values.•The phagocytic activity is enhanced after the target bacteria previously treated with MrALF.•The hemocytic MrALF may play an opsonin during a bacterial invasion.
In this study, a 780-bp full-length cDNA encoding Macrobrachium rosenbergii anti-lipopolysaccharide factor (MrALF) from hemocytes was cloned and identified. The ALF isoform exhibited immune activities, and its concentration in hemolymph was determined. An in vivo expression study showed that the ALF mRNA level of hemocytes could be induced by lipopolysaccharides (LPSs) in an exposure time-dependent manner. Purified recombinant MrALF (rMrALF) expressed in the yeast Pichia pastoris SMD1168 eukaryotic protein expression system demonstrated antibacterial activity against the Gram-negative prawn pathogen Aeromonas hydrophila (minimum inhibitory concentration (MIC) = 0.806 μM, minimum bactericidal concentration (MBC) = 1.606 μM) but not the Gram-positive pathogen Lactococcus garvieae exposed to 25.696 μM of rALF. However, rMrALF can bind to Gram-negative and -positive bacteria. An in vivo expression study demonstrated that the ALF concentrations in prawn hemocytes and plasma were 0.176 μM and 0.168 μM, respectively; following LPS treatment for 6 h, the corresponding concentrations were 0.133 μM in hemocytes and 0.272 μM in plasma. Furthermore, the percentage of hemocytes phagocytosing bacteria cells was higher in hemoyctes previously treated with MrALF than those treated with sterile medium. These results suggest that in the innate immune response of M. rosenbergii, the MrALF from hemocytes may play an opsonin during a bacterial invasion.
Graphical abstractThe concentration of anti-lipopolysaccharide factor (ALF) in plasma of Macrobrachium rosenbergii after LPS treatment. The percentage of hemocytes phagocytosing Aeromonas hydrophila treated with recombinant anti-lipopolysaccharide factor (rALF).Figure optionsDownload full-size imageDownload as PowerPoint slide
