Scientists at the Southwest Foundation for Biomedical Research (SFBR) developed a technique using llama antibodies to detect the seven types of botulinum neurotoxins (BoNTs) simultaneously. BoNTs are about 100 billion times more toxic than cyanide and are part of the CDC’s category A list of potential bioterror threats along with anthrax, Ebola, and other infectious agents.
The llama antibodies, called single domain antibodies (sdAbs), or nanobodies, are molecularly flexible unlike conventional antibodies, the SFBR team points out. “As such, sdAbs may allow biosensors to be regenerable and used over and over without loss of activity,” according to Andrew Hayhurst, Ph.D., an SFBR virologist.
“Also, for some types of BoNT, conventional antibodies are not generally available, and we are filling this biosecurity gap,” Dr. Hayhurst continues. His work is described in the January 21 issue of PLoS ONE. The paper is titled “Llama Single Domain Antibodies Specific for the 7 Botulinum Neurotoxin Serotypes as Heptaplex Immunoreagents.”
The group immunized a llama with harmless versions of seven types of BoNT, and blood was taken to provide antibody-producing cells. The antibody genes were cloned, and the resulting antibodies were tested for their ability to detect BoNT in a selection of drinks.
Dr. Hayhurst and his team are continuing to study the molecular interactions of the llama antibodies to find out why they are so specific and why some of them inhibit toxins. “We not only aim to use the antibodies in BoNT detection tests but also to understand how they bind and inhibit these fascinating molecules,” Dr. Hayhurst notes.
“We are also striving to improve our test by making it more sensitive such that one day it may be able to detect much smaller amounts of toxins found in patients' blood. Since BoNTs also have therapeutic applications with carefully controlled preparations and dosing regimens, there is also an increasing need to monitor BoNT levels in these treatments.”