Biomarkers of the Caseous Lymphadenitis in Sheep by NMR-Based Metabolomics

Abstract

Caseous Lymphadenitis (CLA) is a disease that affects animals, such as sheep, whose etiologic agent is Corynebacterium pseudotuberculosis. In sheep, it causes enormous damages, expressed through a reduction in milk, meat and wool production, or death of infected animals, and, also, difficulties in sterilizing infected animals habitats. Another problem in the control of this disease is its late diagnosis. Thus, we present the pioneer results on NMRbased metabolomics applied in CLA with the aim to detect blood serum profile alterations provoked by a pathogen in C. pseudotuberculosis seropositive sheep. We have compared two types of serum samples: The ones taken from the seropositive animals, which we called infected, and others taken from the seronegative (healthy) animals. Significant metabolomics profile changes occurred in the spectral regions δ: 0.20 to 2.20; 3.20 to 4.40 and 6.40 to 8.00 that refer to hydrogen atoms of proteins, organic acids, alcohols, lipids and some amino acids, correspondingly. When applying chemometrics, a significative separation of 59 serum samples into two groups, sick and healthy animals, was achieved. Additionally, key-metabolites that were only present in the group of sick animals and that can be considered as exclusively bacteria derived were pointed as possible biomarkers for CLA. Therefore, these data might contribute to the development of a non-invasive NMR-based diagnostic method, as well as to bring new insights into the development of new immunoprohylaxis tools.