CLONING OF EQUINE INTERLEUKIN-1 RECEPTOR ANTAGONIST AND DETERMINATIONOF ITS FULL-LENGTH CDNA SEQUENCE

Objectives-To clone equine interleukin 1 receptor antagonist (IL-1ra) and determine its full- length cDNA sequence. Procedure-A cDNA library derived from lipopolysaccharide-stimulated equine monocytes was scree ned by means of plaque hybridization to radiolabeled equine IL-1ra DNA probes generated by means of the polymerase chain reaction. The cDNA nucleotide sequence for equine IL-1ra was determined by use of the did eoxy chain termination technique, analyzed by use of computer software for sequence characteristics, and compared with sequences reported fo r IL-1ra of other species. Results-The cDNA for equine IL-1ra was 1,61 4 base pairs in length with an ORF encoding a peptide of 177 amino aci ds with a predicted molecular mass of 20.427 kd. Similarity between th e amino acid sequence of equine IL-1ra and sequences for human, murine , rat, and lapine IL-1ra was 76%. Similarity between sequence for equi ne IL-1ra and sequences for equine interleukin-1 alpha and equine inte rleukin-1 beta were 22.6 and 24.6%. respectively. Conclusion-Compariso n of the sequence for equine IL-1ra with sequences for IL-1ra of other species indicated a high degree of conservation. Clinical Relevance-R esults establish a basis for studying the roles of interleukin-1 in he althy and diseased joints in horses.