Nuclear Magnetic Resonance-based Metabolomics of Blood Plasma from Dairy Calves Infected with the Main Causal Agents of Bovine Respiratory Disease (BRD)

Abstract

Each year, Bovine Respiratory Disease (BRD) results in significant economic loss in the cattle sector, and novel metabolic profiling and early diagnosis techniques represent a promising tool for developing effective measures for disease management. Here, proton - Nuclear Magnetic Resonance (1H - NMR) spectra were used to characterize metabolites from blood plasma collected from dairy calves intentionally infected with the main BRD causal agents, bovine respiratory syncytial virus (BRSV) and Mannheimia haemolytica (MH), to generate a well-defined metabolomic profile under controlled conditions. In response to infection, 42 metabolites (BRSV = 27, MH = 24) changed in concentration compared to the Baseline (non-infected) state. Fuel substrates and products exhibited a particularly strong effect, reflecting imbalances that occur during the immune response. Glucose levels decreased only during bacterial infection, suggesting that the clinical signs of bacterial BRD are more energetically taxing than those of viral BRD. Furthermore, 1H - NMR spectra from Baseline and Infected samples were discriminated with an accuracy, sensitivity, and specificity ≥ 95% using chemometrics to model the changes associated with disease, suggesting that metabolic profiles can be used for further development and validation of diagnostic tools.

Bovine Respiratory Syncytial Virus (BRSV) Infection Detected in Exhaled Breath Condensate of Dairy Calves by Near-Infrared Aquaphotomics

“…On day 7 post-inoculation of cells, the cell culture supernatant containing −5.20 TCID 50 units of BRSV per mL was collected. Then, 5 mL of the supernatant was administered via a nebulizer (DeVilbiss Pulmo-Neb) through a custom-made face mask to each of five non-vaccinated three-month-old Holstein steers weighing approximately 130 kg and housed in outdoor pens isolated from other cattle at Mississippi State University (Animal Care and Use Committee IACUC-19-037) [17]. Clinical signs (VCD) of respiratory infection, including rectal temperature, heart rate, respiratory rate, assessment of nasal and ocular discharge, presence of cough, breathing pattern, and character of lung sounds, were evaluated before and after infection (Figure 1) [17,34].…”

“…By comparison, analysis using reverse transcription-polymerase chain reaction (RT-PCR), which is currently considered the gold standard for BRSV diagnosis, has 99% sensitivity and specificity [1,3,11]. More recently, analytical techniques such as nuclear magnetic resonance (NMR) and gas chromatography based mass spectrometry (GC-MS) have been used in blood plasma, blood serum, nasal secretions, and exhaled breath condensate to identify biomarkers related to BRDC to create new diagnostic tools that facilitate appropriate treatment [12][13][14][15][16][17].…”