Determination by Immunohistochemistry of Acute Phase Proteins in Naturally Infected Sheep with Listeriosis

Abstract Listeriosis is an infectious and fatal disease affecting domestic mammals, poultry, and humans worldwide. The effectiveness of local tissue expression of acute phase proteins in listeriosis in domestic mammals is not yet clear. The aim of this study is to evaluate the local expression of acute phase proteins in 26 brainstem tissue samples according to the distribution and severity of inflammation due to natural Listeriosis disease in sheep. The study material consisted of 26 brainstem paraffin blocks, including 20 from listeriosis-infected cases and 6 from healthy controls. Sections obtained from the paraffin blocks were subjected to histopathological and immunohistochemical analyses. Histopathological examination revealed normal histological structures in the brainstems of the control group. In contrast, brainstem sections from listeriosis cases exhibited histopathological findings such as micro abscesses composed of neutrophil granulocytes and microglial cells, gliosis, meningitis, congestion, perivascular cuffs, neuronal degeneration, and neuronophagia. Based on the distribution and severity of inflammation, listeriosis cases were categorized into three groups: 5 mild cases (Group I), 8 moderate cases (Group II), and 7 severe cases (Group III). Immunohistochemical analysis demonstrated significantly increased expression levels of C-reactive protein (CRP), Haptoglobin (Hp), and Serum Amyloid A (SAA) in listeriosis groups compared to the control group, with the highest statistical scores observed in Group II and Group III (p<0.001). The findings of this study suggest that acute-phase proteins may play crucial roles in the pathophysiological processes of naturally infected listeriosis and could express locally. Particularly, the increased expression of these proteins with the progression of inflammation may provide valuable insights into disease severity and the infection process.