ABSTRACT

Systemic amyloidosis is frequently reported in a wide variety of domestic animals, including avian, canine, feline, equine and ruminants. In most cases, the amyloid has been identified to be the AA-type. Porcine amyloidosis has been reported less frequently, in fact, descriptions are rare and refer to single cases (Jacob, 1971). Furthermore, the amyloid has not been typed chemically thusfar. In the present report, we have extracted amyloid material from formalin fixed tissue sections. By subsequent amino acid sequencing, a N-terminal fragment was obtained which amino acid sequence showed a high degree of homology with known sequence of bovine and bovine AA-amyloid. This identifies porcine systemic amyloid as AA-amyloid. This is the first report on chemical identification of porcine amyloid. Furthermore, based on the partial sequence obtained, is was established that the amino acid sequence differs from the only porcine SAA sequences available in the public domain. The latter are derived from macrophages, and represent local or tissue-specific SAA (SAA3). This fact, and the similarity to bovine and ovine SAA1 suggests that pig AA-amyloid is derived from the systemic (hepatic) isoform of SAA. It is argued that this is a valuable addition to the sequences from various species already known, since pig SAA apparently has a low tendency to form amyloid. This will contribute to the elucidation of amyloidogenic factors by comparative sequence analysis.