Protein biomarkers that are secreted into the blood from infected host cells following infection may become the basis of early and specific disease diagnostics. To identify such mechanistic biomarkers, two human trophoblast cell lines (JAr and AC-1M88) were infected with Brucella abortus 2308 for 20 hours. Light membrane vesicles were prepared from infected and control cultures and the secretory protein-enriched soluble content recovered for proteomics analysis. Statistical analysis identified 287 and 143 significantly differentially expressed proteins from each of the infected JAr and AC-1M88 trophoblast preparations respetively. Proteins selected from each cell line were used for MRM qualication. Two hundred on (201) peptides corresponding to 113 proteins were monitored. Seventy four (74) proteins were qualified as candidate biomarkers of Brucella diagnosis