Expression of recombinant feline serum amyloid A (SAA) protein

Feline serum amyloid A (SAA) cDNA clone was isolated from a hepatic mRNA of a mixed-breed cat. The feline SAA cDNA clone contains 333 nucleotides and deduced amino acid sequence shows 87.4%, 73.9%, and 65.8% homology with dog , human and mouse SAA respectively. Relative to the human and mouse SAA pro teins, an additional peptide of eight amino acids is specified in the felin e cDNA clone. Recombinant feline SAA (rfSAA) was expressed at high levels u sing pGEX bacterial expression system. Cleavage from the fusion moiety, and purification using glutathione-sepharase yielded pure soluble form of rfSA A. Antibodies generated against rfSAA were specific for feline SAA and show ed no cross-reactivity with human SAA. Furthermore, antibodies against huma n SAA did not react with feline SAA. These results indicate that antigenici ty of feline SAA is totally different from human SAA.