New methodology for Vip3A monitoring in corn resistant to Spodoptera frugiperda (Lepidoptera: Noctuidae)

Here we report the main research results demonstrating the expression of the insecticidal toxin Vip3Aa in transgenic Bt-Vip3Aa corn hybrids, at ‘high dose’ according to the Environmental Protection Agency of the USA. It was also developed a quantitative ELISA assay named TOXIVip, specific against the Vip3Aa protein. The Vip3Aa toxin was cloned and expressed in Escherichia coli (Ec-Vip3Aa), purified by Immobilized Metal Affinity Chromatography (IMAC) and used for the generation of monoclonal antibodies (mAbs). The mAbs were able to recognize the native Vip3Aa protein expressed in transgenic corn plants and were used in the development of the TOXIVip method. Specifically, the TOXIVip method allowed quantifying the expression of the toxin in Bt-Vip3Aa corn hybrids, and aided on corroborating them as complying with the ‘high dose’ criterion. So far, the TOXIVip method was the first quantitative system ever reported for selecting the best Bt-Vip3Aa corn plants showing insecticidal activity according to the highest levels of the Vip3Aa toxin expressed. Advantageously, the TOXIVip method provides a fast and specific procedure to determine the Vip3Aa protein in transgenic plants, particularly in Bt-Vip3Aa corn plants, and also in the environment and as part of the screening tests in the food stock chain. Such system could be determinant to establish the ‘high dose’ criterion during the introduction of new lines and hybrids of Bt-Vip3A corn, also helping in genetic introgression analyses while developing new corn genotypes. This research granted the 2016 Award of the Cuban National Academy of Sciences.