An Approach to Reconfirm Transgenic "Cry" Protein Sequences as Safe for Use in Genetic Engineering by Bioinformatic Tools

Background : Genetically engineered (GM) crops are produced by the insertion of specific genes from Bacillus thuringiensis [Bt] that encode a transgenic protein which must be evaluated for potential safety and allergenicity prior to crop development and market release. Objective : The aim of the present work was to re inspect the allergenicity of Cry 1Ab, Cry 1Ac and Cry 1C transgenic protein sequences using FASTA based bioinformatics tools. Methods : An in silico approach was employed to assess allergenicity and cross-reactivity of three Cry proteins- Cry 1Ab, Cry 1Ac and Cry 1C being preferred transgenic proteins of crop developers in India. A non-allergenic dietary spinach rubisco, a small subunit protein, and a known food allergen Arah 1 were analysed as per recommended criteria, using Full FASTA alignment and 80 amino acid window approach in allergen databases- FARRP and SDAP. Results : None of the transgenic Cry 1Ab, Cry 1Ac and Cry 1C proteins showed sequence similarity of >35% with any known allergenic sequence in allergen databases. Dietary protein showed a high of only 21% similarity with Apim allergen sequence, while Arah 1, a proven food allergen reflected greater than 35% sequence similarity with known allergen such as beta-conglycin under the 80 amino acid window approach. Conclusion : The allergenicity assessment by in silico tools of three Cry proteins, used for development of genetically engineered crops did not indicate significant alignment and similarity with any known allergen(s) in the database. This confirmed the approach for use of Cry proteins as safe transgenic proteins in genetic engineering from allergenicity point of view.