Expression and immunogenicity of enterotoxigenic Escherichia coli heat-labile toxin B subunit in transgenic rice callus.
Enterotoxigenic Escherichia coli is one of the leading causes of diarrhea in developing countries, and the disease may be fatal in the absence of treatment. Enterotoxigenic E. coli heat-labile toxin B subunit (LTB) can be used as an adjuvant, as a carrier of fused antigens, or as an antigen itself. The synthetic LTB (sLTB) gene, optimized for plant codon usage, has been introduced into rice cells by particle bombardment-mediated transformation. The integration and expression of the sLTB gene were observed via genomic DNA PCR and western blot analysis, respectively. The binding activity of LTB protein expressed in transgenic rice callus to G(M1)-ganglioside, a receptor for biologically active LTB, was confirmed by G(M1)-ELISA. Oral inoculation of mice with lyophilized transgenic rice calli containing LTB generated significant IgG antibody titers against bacterial LTB, and the sera of immunized mice inhibited the binding of bacterial LTB to G(M1)-ganglioside. Mice orally immunized with non-transgenic rice calli failed to generate detectable anti-LTB IgG antibody titers. Mice immunized with plant-produced LTB generated higher IgG1 antibody titers than IgG2a, indicating a Th2-type immune response. Mice orally immunized with lyophilized transgenic rice calli containing LTB elicited higher fecal IgA antibody titers than mice immunized with non-transgenic rice calli. These experimental results demonstrate that LTB proteins produced in transgenic rice callus and given to mice by oral administration induce humoral and secreted antibody immune responses. We suggest that transgenic rice callus may be suitable as a plant-based edible vaccine to provide effective protection against enterotoxigenic E. coli heat-labile toxin.
Kim
Tae-Geum
TG
Division of Biological Sciences, Research Center for Bioactive Materials, Chonbuk National University, Jeonju, 561-756, Republic of Korea. tgkim@chonbuk.ac.kr
Kim
Bang-Geul
BG
Kim
Mi-Young
MY
Choi
Jae-Kwon
JK
Jung
Eun-Sun
ES
Yang
Moon-Sik
MS
D000284:Administration, Oral; D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology*; D004768:Enterotoxins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology*; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology*; D029968:Escherichia coli Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology*; D022361:Escherichia coli Vaccines / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology*; D006358:Hot Temperature; D051379:Mice; D012275:Oryza / Q000235:genetics / Q000276:immunology*; D008517:Phytotherapy / Q000379:methods*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000276:immunology; D015202:Protein Engineering; D011994:Recombinant Proteins / Q000276:immunology
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; D011994:Recombinant Proteins; C027538:heat-labile enterotoxin, E coli