The 6 sequences, referred to as SAA1, SAA1 des Arg, SAA2-alpha, SAA2-alpha des Arg, SAA2-beta, and SAA2-beta des Arg, are resolved by electrofocusing into 6 isoforms. SAA1 is the product of one gene, while SAA2-alpha and SAA2-beta, which differ by only a single amino acid, represent allelic sequences of a second gene. Although the first reported AA protein corresponded to SAA2-beta, subsequent analyses showed that the vast majority of the protein isolated from amyloid deposits is derived from SAA1. The SAA2-tat/HIV-sTNFR:Ig construct, and derivatives thereof, may therefore be ideally suited to gene therapy applications that require the local production of potent and specific immune modifiers only when there is active pathology..