Colibacillosi del vitello : indagine morfologica ed immunofenotipica sulla distribuzione di Escherichia coli in relazione allo stato immunitario di vitelli deceduti in corso di patologia enterica spontanea

Neonatal calf enteritis is constantly associated to depletion of gut-associated lymphoid tissue (GALT). The aim of these study is to evaluate GALT lesions in 14 calves from a bio herd, where no drugs are admitted. These calves were necropsied and samples were taken for microbiological examination, with constant Escherichia coli (Ec) isolation, histological and immunohistochemical investigations, these later by means of antibodies against CD3, CD79, and MHC II, Heat Shock Proteins (HSPs) 72 and 27. Severe hyperemia and catarrhal enteritis, severe immunodepletion of the Peyer plaques, lymph nodes and spleen were histologically evident. Immunoistochemically reduced numbers of CD 79+ cells in follicular centres of lymphoid tissue, admixed with macrophages MHC II positive (APC) were detectable. Intense cytoplasm expression of HSPs in enterocytes and APC resident in lymphoid tissues was also evident. Immunodepletion finding appeared to have an important role in the severity of the described lesions, therefore further studies are needed to determine the possible presence and role of other bacterial and viral pathogens, the interaction between Ec, intestinal epithelial cells and GALT to better understand host pathogen balance.