Past research has focused on Salmonella choleraesuis virulence determinants and the interaction of this organism with the porcine immune system. Emphasis was placed on interaction of virulent S. choleraesuis field isolates with neutrophils and macrophages. Results suggested a correlation between relative bacterial virulence and the organisms ability to interfere with phagocyte ingestion, inhibit superoxide anion production, and overall intracellular survivability. A 40 kDal outer membrane protein was identified and determined to be involved with bacterial translocation and eukaryotic cell invasion.