RAPID DETECTION OF BT-CRY TOXINS

摘要

The present invention is based on the use of 1) two polyclonal IgGs against two Cry toxins, 2) Cry toxin receptors isolated from lepidopteran larvae and 3) manual striping methods to manufacture immunochromatographic strips that are useful in detecting a variety of analytes. Immunochromatographic strips, which facilitate rapid detection of analytes are expensive if made using monoclonal antibodies and cannot be affordable for Indian farmers and extension workers. The main objective of the current method was to simplify the development of the immunochromatographic detection method for Cry (Bt) toxin detection using affinity purified polyclonal antibodies specific to the analyte and also to provide a robust and easy method suitable for manufacture of "Cry1Ac/Cry1Ab/Cry2Aa/Cry2Ab toxin" detection strips at affordable cost, under Indian conditions. Anti-Bt (anti-Cry1 Ac or anti-Cry2Aa/Ab or both) antibody or Cry receptor proteins are immobilized on a cellulose nitrate membrane by manual striping. The membrane is blocked using casein or BSA and preservatives. Anti-Bt (anti-Cry1 Ac or anti-Cry2Aa/Ab or both) antibody is labeled with gold and adsorbed on glass-fibre membrane which is placed at the bottom the membrane so as to overlap 2mm. Specificity and accuracy of the assay are greatly enhanced due to the use of antigen-affinity and Protein-A affinity purified polyclonal IgG raised in two different animals (goat and rabbit). The schematic diagram of the Cry toxin detection lateral flow strip assembly is shown in a diagram appended herewith. The strips thus made represent rapid, sensitive devices and methods for detecting the presence of Cry1Ac/Cry1Ab/Cry2Aa/Cry2Ab and crystal toxins either from transgenic plants or in Bt-fermented products. The methods and devices have high sensitivity to detect either single or two Cry toxins simultaneously on a single strip. Use of the present methods provide an assay system which involve a minimal number of steps, and yield reliable results even when used by untrained persons.