Development of highly sensitive chemiluminescence enzyme immunoassay based on the anti-recombinant HC subunit of botulinum neurotoxin type A monoclonal antibodies

Botulinum neurotoxins (BoNTs) are the most poisonous substances ever known. The early detection of these toxins could bear more time for appropriate medical intervention. The standard method for detecting BoNTs is the mouse bioassay, which is time consuming (up to 4 days) and requires a large number of laboratory animals. The immunologic detection methods could detect the toxins within a day, but most of these methods are less sensitive compared with the mouse bioassay due to the lack of high-affinity antibodies. Recently, the recombinant HC subunit of botulinum neurotoxin type A (rAHC) was expressed as an effective vaccine against botulism, indicating that the rAHC could be an effective immunogen that raises the monoclonal antibody (mAb) for detecting BoNT/A. After immunized BALB/c mice with rAHC, 56 mAbs were generated. Two of these mAbs were selected to establish a highly sensitive sandwich chemiluminescence enzyme immunoassay (CLEIA), in which FMMU-BTA-49 and FMMU-BTA-22 were used as capture antibody and detection antibody, respectively. The calculated limit of detection (LOD) based on molecular weight of rAHC and BoNT/A reached 0.45 pg mL−1. This CLEIA can be used in the detection of BoNT/A in matrices such as milk and beef extract. This method has 20–40 fold lower LOD than that of the mouse bioassay and takes only 3 h to complete the detection, indicating that it can be used as a valuable method to detect and quantify BoNT/A.

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► The rAHC could elict highly protective antibody titer as vaccine.
► Two anti-rAHC mAbs were selected to form the sensitive CLEIA for detecting BoNT/A.
► The CLEIA detecting BoNT/A is more sensitive than that of the ELISA reported.