Sequence and functional characterization of feline interleukin 2.

Since the discovery of its involvement in the pathogenesis of feline immunodeficiency virus infection ("cat AIDS") and feline leukemia virus infection, the role of feline interleukin 2 (IL-2) has been a focus of particular interest. The purpose of this study was to clone feline IL-2 cDNA, as well as synthesize bioactive recombinant feline IL-2. The isolation of cDNA encoding feline IL-2 was carried out using a PCR-based strategy and screening of a feline leukocyte cDNA library. Feline IL-2 consists of 154 amino acids including a putative signal sequence and has 81%, 69%, 60% and 64% identity to human, bovine, murine and rat IL-2, respectively. Feline IL-2 cDNA was expressed in COS-7 cells. The secreted protein has CTLL-4 murine cytotoxic T cell proliferative activity characteristic of authentic IL-2. These data confirm the synthesis of bioactive recombinant feline IL-2.