Investigation of a monoclonal antibody against enterotoxigenic Escherichia coli, expressed as secretory IgA1 and IgA2 in plants

Gut Microbes. 2021 Jan-Dec;13(1):1-14. doi: 10.1080/19490976.2020.1859813.


Passive immunization with antibodies is a promising approach against enterotoxigenic Escherichia coli diarrhea, a prevalent disease in LMICs. The objective of this study was to investigate expression of a monoclonal anti-ETEC CfaE secretory IgA antibody in N. benthamiana plants, with a view to facilitating access to ETEC passive immunotherapy. SIgA1 and SIgA2 forms of mAb 68-81 were produced by co-expressing the light and engineered heavy chains with J chain and secretory component in N. benthamiana. Antibody expression and assembly were compared with CHO-derived antibodies by SDS-PAGE, western blotting, size-exclusion chromatography and LC-MS peptide mapping. N-linked glycosylation was assessed by rapid fluorescence/mass spectrometry and LC-ESI-MS. Susceptibility to gastric digestion was assessed in an in vitro model. Antibody function was compared for antigen binding, a Caco-2 cell-based ETEC adhesion assay, an ETEC hemagglutination inhibition assay and a murine in vivo challenge study. SIgA1 assembly appeared superior to SIgA2 in plants. Both sub-classes exhibited resistance to degradation by simulated gastric fluid, comparable to CHO-produced 68-61 SIgA1. The plant expressed SIgAs had more homogeneous N-glycosylation than CHO-derived SIgAs, but no alteration of in vitro functional activity was observed, including antibodies expressed in a plant line engineered for mammalian-like N glycosylation. The plant-derived SIgA2 mAb demonstrated protection against diarrhea in a murine infection model. Although antibody yield and purification need to be optimized, anti-ETEC SIgA antibodies produced in a low-cost plant platform are functionally equivalent to CHO antibodies, and provide promise for passive immunotherapy in LMICs.

Keywords: Enterotoxigenic Escherichia coli; Nicotiana benthamiana; immunotherapy; monoclonal antibody; passive immunization; secretory IgA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Bacterial / genetics
  • Antibodies, Bacterial / immunology
  • Antibodies, Bacterial / metabolism
  • Antibodies, Bacterial / therapeutic use
  • Antibodies, Monoclonal / genetics
  • Antibodies, Monoclonal / immunology*
  • Antibodies, Monoclonal / metabolism
  • Antibodies, Monoclonal / therapeutic use
  • Antibody Affinity
  • Bacterial Adhesion / drug effects
  • Caco-2 Cells
  • Enterotoxigenic Escherichia coli / immunology*
  • Escherichia coli Infections / microbiology
  • Escherichia coli Infections / therapy
  • Gastric Acid / metabolism
  • Glycosylation
  • Humans
  • Immunoglobulin A, Secretory / genetics
  • Immunoglobulin A, Secretory / immunology*
  • Immunoglobulin A, Secretory / metabolism
  • Immunoglobulin A, Secretory / therapeutic use
  • Immunotherapy
  • Mice
  • Plants, Genetically Modified
  • Tobacco / genetics
  • Tobacco / metabolism*


  • Antibodies, Bacterial
  • Antibodies, Monoclonal
  • Immunoglobulin A, Secretory

Grant support

This work was supported by the Bill and Melinda Gates Foundation (Investment ID OPP1194526 (JM) and OPP1173647 (MK)).