title: Anti-lipopolysaccharide factor in Litopenaeus vannamei (LvALF): a broad spectrum antimicrobial peptide essential for shrimp immunity against bacterial and fungal infection.
abstract: Antimicrobial peptides are an essential component of the innate immune system of most organisms. Expressed sequence tag analysis from various shrimp (Litopenaeus vannamei) tissues revealed transcripts corresponding to two distinct sequences (LvALF1 and LvALF2) with strong sequence similarity to anti-lipopolysaccharide factor (ALF), an antimicrobial peptide originally isolated from the horseshoe crab Limulus polyphemus. Full-length clones contained a 528bp transcript with a predicted open reading frame coding for 120 amino acids in LvALF1, and a 623bp transcript with a predicted open reading frame coding for 93 amino acids in LvALF2. A reverse genetic approach was implemented to study the in vivo role of LvALF1 in protecting shrimp from bacterial, fungal and viral infections. Injection of double-stranded RNA (dsRNA) corresponding to the LvALF1 message resulted in a significant reduction of LvALF1 mRNA transcript abundance as determined by qPCR. Following knockdown, shrimp were challenged with low pathogenic doses of Vibrio penaeicida, Fusarium oxysporum or white spot syndrome virus (WSSV) and the resulting mortality curves were compared with controls. A significant increase of mortality in the LvALF1 knockdown shrimp was observed in the V. penaeicida and F. oxysporum infections when compared to controls, showing that this gene has a role in protecting shrimp from both bacterial and fungal infections. In contrast, LvALF1 dsRNA activated the sequence-independent innate anti-viral immune response giving increased protection from WSSV infection.
authors: Marine Biomedicine and Environmental Sciences Center, Medical University of South Carolina, 221 Ft. Johnson Road, Charleston, SC 29412, USA. delavega@musc.edu
authors: Enrique
authors: E
authors: de la Vega
authors: Nuala A
authors: NA
authors: O'Leary
authors: Jessica E
authors: JE
authors: Shockey
authors: Javier
authors: J
authors: Robalino
authors: Caroline
authors: C
authors: Payne
authors: Craig L
authors: CL
authors: Browdy
authors: Gregory W
authors: GW
authors: Warr
authors: Paul S
authors: PS
authors: Gross
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000276:immunology*; D001424:Bacterial Infections / Q000276:immunology / Q000662:veterinary*; D001681:Biological Assay; D020869:Gene Expression Profiling; D020868:Gene Silencing / Q000187:drug effects; D007109:Immunity / Q000187:drug effects / Q000276:immunology*; D007447:Invertebrate Hormones / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D008969:Molecular Sequence Data; D009181:Mycoses / Q000276:immunology / Q000662:veterinary*; D033561:Penaeidae / Q000187:drug effects / Q000276:immunology* / Q000382:microbiology / Q000821:virology; D010802:Phylogeny; D012330:RNA, Double-Stranded / Q000008:administration & dosage / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015996:Survival Rate; D046848:White spot syndrome virus 1 / Q000187:drug effects
chemical_list: D023181:Antimicrobial Cationic Peptides; D007447:Invertebrate Hormones; D012330:RNA, Double-Stranded; D012333:RNA, Messenger