SERUM AMYLOID A IN RUMINANTS: DIAGNOSTIC VALUE AND FOOD CONTAMINATION ASSESSMENT

The aims of the work presented in this thesis were to investigate the bovine acute phase protein Serum Amyloid A, focussing on its value as safety marker in farm animals. SAA can be considered as a natural anti-inflammatory and immunomodulatory agent and local expression of SAA, at the site of the initial acute phase reaction, could protect against the deleterious effects of inflammation. In this study whether SAA can be isolated from tissues of bovine with clinical amyloidosis was investigated. We also investigated if AA fibrils present in milk can be then found in cheese after caseification, i.e. if the process of ripeining can degrade the AA fibrils. In bovine, SAA was identified as potential marker of mastitis, and SAA milk concentration in milk increases before the raising of somatic cells. In this thesis two aspect of the involvement of SAA in food safety were explored: a)the acute phase reaction, strongly focused on the mammary gland. The animal model chosen was water buffalo, since no information is available so far about the acute phase reaction in this species. The acute phase proteins sequences are unknown, and also their concentration in physiological and pathological conditions are not established. b)The possibility that high concentration of SAA in milk induce the formation of amyloid fibrils, which are considered to be potentially dangerous for human safety. Results presented in this thesis advanced the knowledge of the acute phase reaction in water buffalo: the five APPs included in this investigation, namely Serum amyloid A, Haptoglobin, Ceruloplasmin, α1-acid glycoprotein and Lipolysaccaride Binding Protein were sequenced for the first time, and two of them were quantified. In the second part of the thesis, we purified amyloid fibrils from amyloidosis-affected cows, and added purified fibrils at a given concentration in milk before ripening. Results demonstrated the presence of insoluble fibrils in cheese added with amyloid proteins, even if a lower amount of precipitated insoluble SAA could be detected also in negative control cheese.