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Avian defensins.

ABSTRACT: Modulation of defensin expression may be one way to improve animal health and to reduce zoonotic diseases. Defensins are small, cationic, and amphipathic cysteine-rich antibiotic peptides found in plants, insects, mammals and birds. Whereas alpha- and theta-defensins appear to be absent in birds, several beta-defensins have been isolated from avian heterophils. In addition, beta-defensins were found to be constitutively or inducibly expressed at mucosal surfaces of the respiratory, intestinal and urogenital tracts. In this review the current knowledge of the defensin repertoire of birds, their tissue-specific expression, regulation and corresponding biological functions are described.

SUBMITTER: van Dijk A

PROVIDER: S-EPMC7112556 | biostudies-literature | 2008 Jul

REPOSITORIES: biostudies-literature

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Avian defensins.

van Dijk Albert A Veldhuizen Edwin J A EJ Haagsman Henk P HP

Veterinary immunology and immunopathology 20080201 1-2

Modulation of defensin expression may be one way to improve animal health and to reduce zoonotic diseases. Defensins are small, cationic, and amphipathic cysteine-rich antibiotic peptides found in plants, insects, mammals and birds. Whereas alpha- and theta-defensins appear to be absent in birds, several beta-defensins have been isolated from avian heterophils. In addition, beta-defensins were found to be constitutively or inducibly expressed at mucosal surfaces of the respiratory, intestinal an ...[more]

PMID: 18313763

Similar Datasets

Initial insights into structure-activity relationships of avian defensins.

Project description:Numerous ?-defensins have been identified in birds, and the potential use of these peptides as alternatives to antibiotics has been proposed, in particular to fight antibiotic-resistant and zoonotic bacterial species. Little is known about the mechanism of antibacterial activity of avian ?-defensins, and this study was carried out to obtain initial insights into the involvement of structural features or specific residues in the antimicrobial activity of chicken AvBD2. Chicken AvBD2 and its enantiomeric counterpart were chemically synthesized. Peptide elongation and oxidative folding were both optimized. The similar antimicrobial activity measured for both L- and D-proteins clearly indicates that there is no chiral partner. Therefore, the bacterial membrane is in all likelihood the primary target. Moreover, this work indicates that the three-dimensional fold is required for an optimal antimicrobial activity, in particular for gram-positive bacterial strains. The three-dimensional NMR structure of chicken AvBD2 defensin displays the structural three-stranded antiparallel ?-sheet characteristic of ?-defensins. The surface of the molecule does not display any amphipathic character. In light of this new structure and of the king penguin AvBD103b defensin structure, the consensus sequence of the avian ?-defensin family was analyzed. Well conserved residues were highlighted, and the potential strategic role of the lysine 31 residue of AvBD2 was emphasized. The synthetic AvBD2-K31A variant displayed substantial N-terminal structural modifications and a dramatic decrease in activity. Taken together, these results demonstrate the structural as well as the functional role of the critical lysine 31 residue in antimicrobial activity.

| S-EPMC3293588 | biostudies-literature

Developmental and Tissue Patterns of the Basal Expression of Chicken Avian <i>?</i>-Defensins.

Project description:Defensins are a class of antimicrobial peptides in vertebrates that function as the first line of innate immunity with potent antimicrobial and immunomodulatory activities. Fourteen defensins, namely, avian ?-defensin 1 to 14 (AvBD1-14), have been identified in chickens. Before characterizing the role of AvBDs in innate immunity during the early development of chickens, we collected tissue segments from the liver, spleen, and gastrointestinal (GI) tract including the esophagus, crop, proventriculus, gizzard, duodenum, jejunum, ileum, cecum, and colon from broilers at days 1, 3, 7, 14, and 28. After RNA isolation and reverse transcription, we determined the expression levels of the 14 AvBD genes in these tissues during the first 28 days after hatching by real-time PCR. The results suggested the AvBDs were widely expressed in the chicken liver, spleen, and gastrointestinal (GI) tract. Interestingly, we did not detect AvBD11 expressed in the GI tract, even in the liver and spleen. Additionally, AvBDs were differentially expressed in the chicken GI tract. AvBD5 and AvBD14 were expressed most abundantly in the proximal GI tract, especially the esophagus and crop. Moreover, AvBD5, AvBD7, AvBD9, and AvBD14 were expressed in an inverted-V pattern with the peak being the observed expression at days 3, 7, or 14 in the chicken spleen, esophagus, duodenum, and cecum. Other AvBDs presented biphasic or inverted-V expression patterns in different tissues. The expression levels of all detected AvBDs were strengthened after hatching rather than decreasing steadily. Therefore, AvBDs were found to be expressed widely in the chicken liver, spleen, and GI tract and their expression levels were primarily up regulated during the early development of chicken, implying the potential essential roles of AvBDs in early innate defense and infection resistance of chickens.

| S-EPMC7787727 | biostudies-literature

Neutrophil Defensins (Alpha-Defensins)

Project description:In the HPLC high-resolution ESI-MS profiles of Gingival Crevicular Fluid, four proteins, with exp. monoisotopic ion [M+H]+ at 3440.54 ± 0.06 m/z, 3369.50± 0.06 m/z, 3484.51 ± 0.06 m/z and 3707.77 ± 0.06, eluting between 24.5-26.6 minutes, were detected. The monoisotopic mass values and the manual inspection of the high-resolution MS/MS spectra of the ions at [M+5H]+5 at 689.31, 675.10, 698.11 and 742.76 m/z, and of the ions at [M+4H]+4 at 843.63, 872.39 m/z allowed to establish that the four proteins were alpha defensins 1, 2, 3 and 4.

2020-07-09 | PXD016049 | Pride

Human Salivary Neutrophil Defensins (Alpha-Defensins)

Project description:In the HPLC high-resolution ESI-MS profiles of both Predominantly Antibody Deficiency syndromes subjects and healthy controls saliva samples, four proteins, with exp. monoisotopic ion [M+H]+ at 3440.54 ± 0.06 m/z, 3369.50± 0.06 m/z, 3484.51 ± 0.06 m/z and 3707.77 ± 0.06, eluting between 24.5-26.6 minutes, were detected. The monoisotopic mass values and the manual inspection of the high-resolution MS/MS spectra of the ions at [M+5H]+5 at 689.31, 675.10, 698.11 and 742.76 m/z, and of the ions at [M+4H]+4 at 843.63, 872.39 m/z allowed to establish that the four proteins were alpha defensins 1, 2, 3 and 4.

2020-01-09 | PXD012688 | Pride

Effects of avian infectious bronchitis with Newcastle disease and Marek's disease vaccinations on the expression of toll-like receptors and avian ?-defensins in the kidneys of broiler chicks.

Project description:The aim of this study was to determine the effect of vaccinations for avian infectious bronchitis with Newcastle disease (IB/ND) and Marek's disease (MD) on the expression of toll-like receptors (TLR) that recognize viral RNA and microbial DNA, and AvBD in chick kidneys. Day-old chicks were vaccinated with MD or IB/ND vaccines or received no treatment (control group). The gene expression of TLR and AvBD in the kidneys of 3-day-old chicks and 10-day-old chicks was examined using real-time PCR. The localization of AvBD2 and AvBD4 was examined by immunohistochemistry at day three only. At 3 days of age, the expression of TLR7 and TLR21 was significantly higher in the IB/ND group (but not in the MD group) than in the control group. Conversely, at 10 days of age there was no significant difference in the expression of the three TLR between groups. In the 3-day-old chicks the expression levels of AvBD4, 5, 6, and 7 were higher in the MD group than in the control group. Furthermore, at this age, the expression levels of other AvBD were not significantly different between the control and vaccination (MD and IB/ND) groups. At 10 days of age, no AvBD expression was affected by MD and IB/ND vaccinations. Immunohistochemistry results localized AvBD2 in the leukocytes in the interstitial tissue and AvBD4 in the surface of microvillus epithelial cells of renal tubules, and in the epithelial cells of the collecting ducts and ureter. The localization of AvBD2 and AvBD4 was identified in all chicks. We suggest that the expression of innate immune molecules (including TLR and AvBD) in kidneys could be modulated by MD and IB/ND vaccination when performed at the day-old stage. Although the effects of both vaccinations may subside within 10 days, the enhanced expression of those innate immune molecules may support the innate immunodefense function in the kidneys of young chicks.

| S-EPMC7486820 | biostudies-literature

Alpha-defensins in enteric innate immunity: functional Paneth cell alpha-defensins in mouse colonic lumen.

Project description:Paneth cells are a secretory epithelial lineage that release dense core granules rich in host defense peptides and proteins from the base of small intestinal crypts. Enteric alpha-defensins, termed cryptdins (Crps) in mice, are highly abundant in Paneth cell secretions and inherently resistant to proteolysis. Accordingly, we tested the hypothesis that enteric alpha-defensins of Paneth cell origin persist in a functional state in the mouse large bowel lumen. To test this idea, putative Crps purified from mouse distal colonic lumen were characterized biochemically and assayed in vitro for bactericidal peptide activities. The peptides comigrated with cryptdin control peptides in acid-urea-PAGE and SDS-PAGE, providing identification as putative Crps. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry experiments showed that the molecular masses of the putative alpha-defensins matched those of the six most abundant known Crps, as well as N-terminally truncated forms of each, and that the peptides contain six Cys residues, consistent with identities as alpha-defensins. N-terminal sequencing definitively revealed peptides with N termini corresponding to full-length, (des-Leu)-truncated, and (des-Leu-Arg)-truncated N termini of Crps 1-4 and 6. Crps from mouse large bowel lumen were bactericidal in the low micromolar range. Thus, Paneth cell alpha-defensins secreted into the small intestinal lumen persist as intact and functional forms throughout the intestinal tract, suggesting that the peptides may mediate enteric innate immunity in the colonic lumen, far from their upstream point of secretion in small intestinal crypts.

| S-EPMC2788835 | biostudies-other

Avian

Project description:RNA virome in wild birds

| PRJNA472212 | ENA

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Project description:Viromes of Anseriformes and Charadriiformes

| PRJNA505206 | ENA

Plant Defensins from a Structural Perspective.

Project description:Plant defensins form a family of proteins with a broad spectrum of protective activities against fungi, bacteria, and insects. Furthermore, some plant defensins have revealed anticancer activity. In general, plant defensins are non-toxic to plant and mammalian cells, and interest in using them for biotechnological and medicinal purposes is growing. Recent studies provided significant insights into the mechanisms of action of plant defensins. In this review, we focus on structural and dynamics aspects and discuss structure-dynamics-function relations of plant defensins.

| S-EPMC7432377 | biostudies-literature

Defensins of Grasses: A Systematic Review.

Project description:The grass family (Poaceae) is one of the largest families of flowering plants, growing in all climatic zones of all continents, which includes species of exceptional economic importance. The high adaptability of grasses to adverse environmental factors implies the existence of efficient resistance mechanisms that involve the production of antimicrobial peptides (AMPs). Of plant AMPs, defensins represent one of the largest and best-studied families. Although wheat and barley seed ?-thionins were the first defensins isolated from plants, the functional characterization of grass defensins is still in its infancy. In this review, we summarize the current knowledge of the characterized defensins from cultivated and selected wild-growing grasses. For each species, isolation of defensins or production by heterologous expression, peptide structure, biological activity, and structure-function relationship are described, along with the gene expression data. We also provide our results on in silico mining of defensin-like sequences in the genomes of all described grass species and discuss their potential functions. The data presented will form the basis for elucidation of the mode of action of grass defensins and high adaptability of grasses to environmental stress and will provide novel potent molecules for practical use in medicine and agriculture.

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