Novel and Highly Specific Monoclonal Antibody to Acidovorax citrulli and Development of ELISA-Based Detection in Cucurbit Leaves and Seed

A novel monoclonal antibody (MAb) specific to the seedborne bacterium Acidovorax citrulli was produced. MAb 11E5 reacted specifically with 19 strains of A. citrulli but not with three closely related bacteria in the family Comamonadaceae (i.e., A. facilis, Comamonas acidovorans, and C. testosteroni) and another seven phytopathogenic bacteria. Moreover, this MAb detected a strain of A. citrulli that was not detected by a commercial enzyme-linked immunosorbent assay (ELISA)-based kit and a commercial immunochromatographic strip test. In Western blot analysis, MAb 11E5 reacted with an A. citrulli protein of a molecular mass >170 kDa. MAb 11E5 was employed to develop two sandwich ELISA systems: MAb captured-sandwich ELISA (MC-sELISA) and polyclonal antibody captured-sandwich ELISA (PC-sELISA). MC-sELISA was 10 times more sensitive than PC-sELISA for detection of A. citrulli in cucurbit leaf and seed extracts. The detection limit of the MC-sELISA was 5 × 104 CFU/ml. Detection of A. citrulli in naturally infected cucurbit leaves, fruit, and seed was also feasible using MC-sELISA. The newly established MCsELISA provides another alternative for specific detection of A. citrulli in cucurbits and can be applied for routine field inspection.

Human infection with Delftia tsuruhatensis isolated from a central venous catheter

We present the case of a patient with catheter-related infection caused by Delftia tsuruhatensis, a newly described species closely related to Delftia acidovorans (formerly Comamonas acidovorans). To date, D. tsuruhatensis has not been described as a pathogen. To the best of our knowledge, this is the first report describing D. tsuruhatensis as the causative agent of a human infection.