Mutational analysis of chicken interleukin 2.

Chicken interleukin 2 (chIL-2) has low, but significant, homology to both mammalian IL-2 and mammalian IL-15. In view of its unique phylogenetic position and potential use as a vaccine adjuvant, a detailed mutational analysis for critical functional sites was undertaken. It was found that Asp17 is a critical N terminal contact site for binding to the putative chIL-2 receptor, which is similar to results obtained for mammalian IL-2 and IL-15. Analysis of the C terminus did not reveal a single critical amino acid. However, deletion mutant studies demonstrated that removal of C terminal amino acids yielded proteins with decreased bioactivity and that this decrease was a function of the number and kind of amino acids removed. This study is the first non-mammalian IL-2 mutational analysis and proposes a model for the interaction between chIL-2 and its receptor.

Uptake and metabolism of iodine is crucial for the development of thyroiditis in obese strain chickens.

To assess the importance of the role of thyroidal iodine in the pathogenesis of thyroiditis in the obese strain (OS) chicken, a model of spontaneous and severe disease, we studied the effect of antithyroid drugs that reduce thyroidal iodine or prevent its metabolism. Reduction of thyroidal iodine was achieved with KClO4, an inhibitor of iodine transport and mononitrotyrosine (MNT), a drug that promotes loss of thyroidal iodine as iodotyrosines. A regimen consisting of KClO4 and MNT administration beginning in ovo and continuing after hatching reduced thyroidal infiltration to 2% of control values and decreased thyroglobulin antibody (TgAb) production for as long as 9 wk. Untreated birds had severe disease by 5 wk of age. The suppression of disease was independent of TSH, not mediated by generalized immunosuppression and reversed by excess dietary iodine. Two drugs that inhibit the metabolism of iodine, propylthiouracil (PTU) and aminotriazole, reduced thyroidal infiltration and TgAb levels, although to a lesser extent. When splenocytes from OS chickens with thyroiditis were transferred to Cornell strain (CS) chickens, a related strain that develops late onset mild disease, only the recipients that were iodine supplemented developed thyroiditis. In conclusion, autoimmune thyroiditis in an animal model can be prevented by reducing thyroidal iodine or its metabolism and optimal effects require intervention at the embryonic stage.