Assessment of potential adjuvanticity of Cry proteins

Regul Toxicol Pharmacol. 2016 Aug:79:149-155. doi: 10.1016/j.yrtph.2016.04.005. Epub 2016 Apr 20.

Abstract

Genetically modified (GM) crops have achieved success in the marketplace and their benefits extend beyond the overall increase in harvest yields to include lowered use of insecticides and decreased carbon dioxide emissions. The most widely grown GM crops contain gene/s for targeted insect protection, herbicide tolerance, or both. Plant expression of Bacillus thuringiensis (Bt) crystal (Cry) insecticidal proteins have been the primary way to impart insect resistance in GM crops. Although deemed safe by regulatory agencies globally, previous studies have been the basis for discussions around the potential immuno-adjuvant effects of Cry proteins. These studies had limitations in study design. The studies used animal models with extremely high doses of Cry proteins, which when given using the ig route were co-administered with an adjuvant. Although the presumption exists that Cry proteins may have immunostimulatory activity and therefore an adjuvanticity risk, the evidence shows that Cry proteins are expressed at very low levels in GM crops and are unlikely to function as adjuvants. This conclusion is based on critical review of the published literature on the effects of immunomodulation by Cry proteins, the history of safe use of Cry proteins in foods, safety of the Bt donor organisms, and pre-market weight-of-evidence-based safety assessments for GM crops.

Keywords: Adjuvant; Bacillus thuringiensis; Cry proteins; Food/feed safety; GM crops; Genetic modification.

Publication types

  • Review

MeSH terms

  • Animals
  • Bacillus thuringiensis Toxins
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / immunology
  • Bacterial Proteins / metabolism
  • Consumer Product Safety*
  • Crops, Agricultural / genetics*
  • Crops, Agricultural / immunology
  • Crops, Agricultural / metabolism
  • Crops, Agricultural / parasitology
  • Endotoxins / genetics*
  • Endotoxins / immunology
  • Endotoxins / metabolism
  • Food Safety*
  • Gene Expression Regulation, Plant
  • Genotype
  • Hemolysin Proteins / genetics*
  • Hemolysin Proteins / immunology
  • Hemolysin Proteins / metabolism
  • Host-Parasite Interactions
  • Humans
  • Insecta / growth & development*
  • Insecta / metabolism
  • Pest Control, Biological / methods*
  • Phenotype
  • Plants, Genetically Modified / genetics*
  • Plants, Genetically Modified / immunology
  • Plants, Genetically Modified / metabolism
  • Plants, Genetically Modified / parasitology
  • Risk Assessment

Substances

  • Bacillus thuringiensis Toxins
  • Bacterial Proteins
  • Endotoxins
  • Hemolysin Proteins
  • insecticidal crystal protein, Bacillus Thuringiensis