title: Function of an anti-lipopolysaccharide factor (ALF) isoform isolated from the hemocytes of the giant freshwater prawn Macrobrachium rosenbergii in protecting against bacterial infection.
abstract: 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)=0.806μM, minimum bactericidal concentration (MBC)=1.606μM) but not the Gram-positive pathogen Lactococcus garvieae exposed to 25.696μM 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 0.176μM and 0.168μM, respectively; following LPS treatment for 6h, the corresponding concentrations were 0.133μM in hemocytes and 0.272μM 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.
authors: Strong Biotech Corporation, Taipei 115, Taiwan, ROC.
authors: Chia-Chen
authors: CC
authors: Liu
authors: Department of Microbiology, Soochow University, Taipei 111, Taiwan, ROC.
authors: Chien-Pang
authors: CP
authors: Chung
authors: Department of Microbiology, Soochow University, Taipei 111, Taiwan, ROC.
authors: Chang-Yi
authors: CY
authors: Lin
authors: Department of Microbiology, Soochow University, Taipei 111, Taiwan, ROC. Electronic address: hhsung@scu.edu.tw.
authors: Hung-Hung
authors: HH
authors: Sung
mesh_terms: D016980:Aeromonas hydrophila / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D060829:Arthropod Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology / Q000502:physiology*; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D060467:Disease Resistance; D006434:Hemocytes / Q000378:metabolism*; D017045:Lactococcus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D033541:Palaemonidae / Q000378:metabolism*; D010587:Phagocytosis / Q000235:genetics; D010843:Pichia / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D060829:Arthropod Proteins; D018076:DNA, Complementary
keywords: Anti-lipopolysaccharide factor; Antibacterial activity; Macrobrachium rosenbergii; Phagocytic activity