Our exclusive shark platform
Conventional vertebrate immunoglobulins (Igs) are tetramers of two heavy and two light chains, in which the variable domains of each chain (VH and VL, respectively) assemble to form the antigen-binding site.
In 1993, a research team led by Hamers-Casterman et al. made the discovery of heavy-chain-only antibodies in the sera of camelid species, specifically in llamas and camels. Two years later, it was reported that sharks and other cartilaginous fish also produce a distinct type of heavy-chain-only antibodies called Ig new antigen receptors (IgNARs). These antibodies are unique to the immune system of sharks and are structurally different from the heavy-chain-only antibodies found in camelids.
VHH versus vNAR:
The heavy-chain-only antibodies found in camelids consist of two identical heavy chains. Each heavy chain comprises two constant domains (CH2 and CH3), a hinge region, and a variable VHH domain responsible for antigen recognition. The binding of antigens by VHH domains is facilitated by three complementarity-determining regions (CDRs): CDR1, CDR2, and CDR3.
In contrast, IgNARs are composed of two identical heavy chains, each consisting of five constant domains (CNAR1 – 5) and a variable vNAR domain responsible for antigen recognition. The vNAR domain binds to antigens through CDR1, CDR3, and two additional small HV loops (HV2 and HV4). It is important to note that vNARs belong to the Ig superfamily and exhibit a ß-sandwich fold comprising only eight strands.
Why use vNARs?
- Superior detection of human antigens due to evolutionary distance from mammal VH domains.
- Unique paratope structure enriches epitope diversity for broad antigen coverage.
- Exceptional resistance to high pH, temperature, and organic solvents due to high urea concentration in shark blood.
- Reduced cross-reactivity, particularly against mammalian biomarkers, ensuring greater specificity.
- vNARs do not bind to mammalian Fc receptors, avoiding platelet activation commonly seen with IgG antibodies in flow cytometry assays.
- Background reduction as vNARs do not bind to rheumatoid factors, preventing false positive results.
- Accurate measurement of complement components by using vNARs against anti-complement components, avoiding complement system activation and false results.
Jotbody’s approach: Nanobodies from whitespotted bamboo sharks
The vNAR of IgNAR from several species of shark, including nurse shark and wobbegong shark, is a valid alternative to camelids-derived products. Unfortunately, the large size of shark species together with the impossibility of captivity, slow maturity, aggressive temper, and unpredictable behavior are the major issues hampering the success of vNAR-derived products.
To address these issues, we have established and validated a nanobody discovery platform using a local small shark species, the whitespotted bamboo shark, commonly kept as a home aquarium fish. This species is known for its docility and small size, allowing for large-scale husbandry and cost-effective production of superior nanobodies.
Discover the groundbreaking realm of nanobodies by delving into the comprehensive article “Single Domain Antibody: Advantages and Applications in Pharma” on Pharma Focus Asia’s website (https://www.pharmafocusasia.com/articles/single-domain-antibody).
Read more about our work:
- Bamboo sharks for affordable single domain antibody production. Front. Bioeng. Biotechnol. 9:792111
- Cas9-based local enrichment and genomics sequence revision of megabase-size shark immunoglobulin new antigen receptor loci. J Immunol. 2022 Jan 1;208(1):181-189
- The White-Spotted Bamboo Shark Genome Reveals Chromosome Rearrangements and Fast-Evolving Immune Genes of Cartilaginous Fish. Iscience. 2020; 23(11): 101754