Double antibody pairs sandwich-ELISA (DAPS-ELISA) detects Acidovorax citrulli serotypes with broad coverage

PLoS One. 2020 Aug 27;15(8):e0237940. doi: 10.1371/journal.pone.0237940. eCollection 2020.

Abstract

Acidovorax citrulli, a seedborne bacterium and quarantine pest, causes the devastating bacterial fruit blotch disease in cucurbit plants. Immunological assays such as ELISA are widely used in routine field inspections for this bacterium. However, to the best of our knowledge, none of the currently available monoclonal antibodies (MAbs) can detect all common A. citrulli strains. We therefore aimed to produce a panel of MAbs and to develop an ELISA-based method capable of detecting all A. citrulli strains. We used a high-throughput bead array technique to screen and characterize A. citrulli-specific MAbs produced from hybridoma clones. The hybridoma library was simultaneously screened against five A. citrulli strains (PSA, KK9, SQA, SQB and P) and the closely related bacterium, Delftia acidovorans. Three MAbs exhibiting different binding patterns to A. citrulli were used to develop an ELISA-based method called "double antibody pairs sandwich ELISA" (DAPS-ELISA). DAPS-ELISA employing mixtures of MAbs was able to specifically detect all 16 A. citrulli strains tested without cross-reactivity with other bacteria. By contrast, our previously developed MAb capture-sandwich ELISA (MC-sELISA) and a commercial test kit detected only 15 and 14 of 16 strains, respectively. The sensitivity of the DAPS-ELISA ranged from 5×105 to 1×106 CFU/mL, while those of the MC-sELISA and the commercial test kit ranged from 5×104 to 1×107 CFU/mL and 5×104 to 5×105 CFU/mL, respectively. DAPS-ELISA thus represents an alternative method enabling rapid, accurate, and inexpensive detection of all A. citrulli strains. The method can be applied to seed testing prior to planting as well as to routine field inspections.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / immunology*
  • Antibodies, Monoclonal / immunology*
  • Comamonadaceae / immunology*
  • Enzyme-Linked Immunosorbent Assay / methods*
  • Hybridomas
  • Limit of Detection
  • Serogroup*

Substances

  • Antibodies, Bacterial
  • Antibodies, Monoclonal

Supplementary concepts

  • Acidovorax citrulli

Grants and funding

This work was financially supported by the National Science and Technology Development Agency (NSTDA, grant number P-19-51272) and the National Center for Genetic Engineering and Biotechnology (BIOTEC, grant number P-15-50886).