Evaluation of antidiphtheria toxin nanobodies

Abstract

Nanobodies are the smallest fragments of naturally occurring single-domain antibodies that have evolved to be fully functional in the absence of a light chain. Conventional antibodies are glycoproteins comprising two heavy and two light chains. Surprisingly, all members of the Camelidae family possess a fraction of antibodies devoid of both light chains and the first constant domain. These types of antibodies are known as heavy-chain antibody (HcAb) nanobodies. There are three subclasses of IgG in dromedaries, namely IgG1, IgG2, and IgG3 of which IgG2 and IgG3 are of the HcAb type. These heavy chain antibodies constitute approximately 50% of the IgG in llama serum and as much as 75% of the IgG in camel serum. In the present work, the different IgG subclasses from an immunized camel (Camelus dromedarius) with divalent diphtheria-tetanus vaccine were purified using their different affinity for protein A and protein G and their absorbance measured at 280 nm. Purity control and characterization by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis of IgG subclasses was done under reducing conditions. Protein bands were visualized after staining with Coomassie Blue, showing two bands at 50 kDa and 30 kDa for IgG1, while IgG2 and IgG3 produced only one band at 46 kDa and 43 kDa, respectively. An enzyme-linked immunosorbent assay test using diphtheria toxin and purified IgG subclasses from the immunized camel were performed to evaluate their efficiency. Compared with conventional IgG1, heavy chain antibodies (nanobodies) were shown to be more efficient in binding to diphtheria toxin antigen. This study revealed the possibility of using IgG2 and IgG3 nanobodies as an effective antitoxin for the treatment of diphtheria in humans.

Broadly Neutralizing Antibodies for Influenza: Passive Immunotherapy and Intranasal Vaccination

“…Camelid IgG2 and IgG3 lack light chains and C H 1 domains. The hinge region of IgG2 is longer than that of IgG3 (the model is representative) [ 85 ]. ( C ) V H H, known as a nanobody, consists of a variable domain of camelid IgG (IgG2 or IgG3) and forms a paratope with a single domain.…”

Distribution of immunoglobulin G antibody secretory cells in small intestine of Bactrian camels (Camelus bactrianus)

“…Because their antigen-binding domain consists of a single variable domain (referred to as VHH), which have smaller size [ 3 ], high level and stable expression in many vectors (such as Escherichia coli [ 7 ], Saccharomyces cerevisiae [ 8 ], tobacco plants [ 9 ] and Lactobacilli [ 10 ]), better tissue penetration, enlarge the antigen binding repertoire [ 11 ] and low immunogenicity. It is a useful tool for treating some diseases [ 12 ] (such as anti-diphtheria toxin [ 13 ], anti-α-cobratoxin [ 14 ]).…”

Enhanced Delivery of 4-Thioureidoiminomethylpyridinium Perchlorate in Tuberculosis Models with IgG Functionalized Poly(Lactic Acid)-Based Particles

“…Camel IgG is known to be a good therapeutic agent itself [44,45]. Here, it was applied for macrophage targeting, but its own therapeutic activity against tuberculosis is also possible.…”