title: Selenium supplementation restores innate and humoral immune responses in footrot-affected sheep.
abstract: Dietary selenium (Se) alters whole-blood Se concentrations in sheep, dependent upon Se source and dosage administered, but little is known about effects on immune function. We used footrot (FR) as a disease model to test the effects of supranutritional Se supplementation on immune function. To determine the effect of Se-source (organic Se-yeast, inorganic Na-selenite or Na-selenate) and Se-dosage (1, 3, 5 times FDA-permitted level) on FR severity, 120 ewes with and 120 ewes without FR were drenched weekly for 62 weeks with different Se sources and dosages (30 ewes/treatment group). Innate immunity was evaluated after 62 weeks of supplementation by measuring neutrophil bacterial killing ability. Adaptive immune function was evaluated by immunizing sheep with keyhole limpet hemocyanin (KLH). The antibody titer and delayed-type hypersensitivity skin test to KLH were used to assess humoral immunity and cell-mediated immunity, respectively. At baseline, FR-affected ewes had lower whole-blood and serum-Se concentrations; this difference was not observed after Se supplementation. Se supplementation increased neutrophil bacterial killing percentages in FR-affected sheep to percentages observed in supplemented and non-supplemented healthy sheep. Similarly, Se supplementation increased KLH antibody titers in FR-affected sheep to titers observed in healthy sheep. FR-affected sheep demonstrated suppressed cell-mediated immunity at 24 hours after intradermal KLH challenge, although there was no improvement with Se supplementation. We did not consistently prevent nor improve recovery from FR over the 62 week Se-treatment period. In conclusion, Se supplementation does not prevent FR, but does restore innate and humoral immune functions negatively affected by FR.
authors: Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, United States of America.
authors: Jean A
authors: JA
authors: Hall
authors: William R
authors: WR
authors: Vorachek
authors: Whitney C
authors: WC
authors: Stewart
authors: M Elena
authors: ME
authors: Gorman
authors: Wayne D
authors: WD
authors: Mosher
authors: Gene J
authors: GJ
authors: Pirelli
authors: Gerd
authors: G
authors: Bobe
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology; D019587:Dietary Supplements; D005260:Female; D005535:Foot Rot / Q000276:immunology* / Q000473:pathology; D006433:Hemocyanins / Q000494:pharmacology; D007111:Immunity, Cellular / Q000187:drug effects; D056724:Immunity, Humoral / Q000187:drug effects*; D007114:Immunization; D012643:Selenium / Q000494:pharmacology*; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology* / Q000473:pathology; D013997:Time Factors
chemical_list: D000276:Adjuvants, Immunologic; D000906:Antibodies; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin; D012643:Selenium