Select the Best-Fit Host Species for VHH Discovery

Equipped with a world-leading VHH development platform and professional scientific staff, Creative Biolabs is proud to support high-efficiency VHH development projects for our customers all over the world. Compared with conventional IgG, single domain antibodies present better properties, such as smaller size and higher penetrability, making them one of the most promising candidates for drug discovery and other applications. Currently, our scientists can generate novel VHHs from different species, including llamas, alpacas, camels, and even sharks.

Llama

Like all members of the camelid family, llama antibodies have three IgG subclasses: the conventional IgG₁, and the non-conventional IgG₂ and IgG₃. Compared with IgG₁, there is a splicing defect in the CH1 exon which results in the absence of the CH1 domain in both IgG₂ and IgG₃. Additionally, many camel VHH sequences contain an extra pair of Cys residues in the H1 and H3 loops, forming an interloop disulfide bond. However, the frequency of this additional disulfide bond is relatively low in llamas, and their H3 loop is significantly shorter than that of camel VHHs.

Alpaca

The alpaca is a species of South American camelid often confused with the llama. Depending on its fiber, the alpaca can be divided into two major breeds: the Huacaya alpaca and the Suri alpaca. Compared with camels and llamas, alpacas are smaller, more tractable and widely available. Alpaca sera IgG consists of almost 50% heavy chain-only antibodies (HCAbs), most of which are of the short-hinge variety. In addition, there is only one IGHM gene with a functional CH1 splicing site in the alpaca genome.

Camel

The camel is an even-toed ungulate in the genus Camelus. In general, camels can be divided into two breeds: the one-humped Arabian camel which makes up 94% of the world's camel population, and the two-humped Bactrian camel, which makes up the remainder. Compared with South American camelid species, the percentage of HCAbs in the blood of camels is significantly higher, ranging from 50% to 80%.

Shark

As a typical species of cartilaginous fish, sharks have been around for over 500 million years. Compared with the various immunoglobulin isotypes in other species, sharks mainly produce IgM, IgW, and IgNAR (immunoglobulin new antigen receptor). IgNAR is a heavy chain homodimer consisting of five constant domains and one variable region (VNAR). VNAR has proven to be a valuable source for the development of VHHs. Relative to the HCAbs in camelids, shark IgNARs are slightly less abundant, making up about 5% of the total immunoglobulins in the blood.

With extensive rich experience in VHH development, Creative Biolabs now offers a variety of species to meet the special needs of our clients. If you are interested in our service, please do not hesitate to contact us for more details.

Published Data

Fig. 1 Comparisons of structures among conventional antibody IgG and natural VHH derived from camelids and sharks.^1,2

This article provides an overview regarding the applications of sdAbs from different sources as new biomarker detectors. Single-domain antibodies derived from camelids (VHH) and those derived from sharks (VNAR) exhibit numerous similarities. Both are composed of a single variable domain, resulting in the formation of small antibody fragments with relatively low molecular weights. Besides, they demonstrate high thermal stability under extreme temperatures and conditions and exhibit high affinity binding to their target antigens. VHH and VNAR have the potential to be utilized in various of biomedical research applications, the development of diagnostic assays, and as a basis for potential therapeutic uses. However, there are also notable differences. VHH is derived from camelids, whereas VNAR originates from sharks, resulting in structural variations, including the absence of the CH1 domain observed in conventional antibodies in VNAR. Another discrepancy is their capacity to identify specific types of antigens, with VNAR demonstrating enhanced abilities to recognize epitopes that are inaccessible to conventional antibodies. Currently, VHH may have reached a more advanced stage in certain fields due to its longer development history. Conversely, recently discovered VNARs might demonstrate distinctive advantages in novel applications. Furthermore, the production methods for VHH and VNAR may diverge, potentially influencing their cost-effectiveness and scalability.

FAQ

1. How does immunization differ between different camelid species?

Immunization may vary between species. Camels often receive numerous injections of the target antigen over several weeks, while llamas and alpacas typically receive lower doses. The main distinctions include the amount of antigen that can be delivered and metabolic variables that influence the immunological response.

2. What considerations should be made regarding the host species when planning VHH library construction?

When constructing a VHH library, researchers must consider genetic diversity, the availability of lymphatic tissue, and the ease of collecting blood for B cell isolation. Additionally, during the immunization process, the animal's health and well-being, as well as the size of their spleen and lymph nodes, may affect the quantity and quality of B cells that can be extracted.

3. What impact does the host species have on the quality and affinity of the resulting VHH antibodies?

Genetic diversity and changes in immune system dynamics between host species influence the production of VHH antibodies with varying affinities and specificities. Generally, all camelid species have the ability to produce strong antibodies. However, antigen presentation and overall health can impact the quality of VHH antibodies.

4. What practical considerations should be taken into account when selecting a host species for VHH discovery?

Several practical considerations should be addressed before selecting host animals, including the animal's size and ease of handling, the logistical feasibility of housing and caring for the species, economic factors (such as the cost of acquisition, housing, and maintenance), and the availability of technical expertise for managing and working with a specific species.

5. What is the impact of the selected host species on the potential applications of the VHH antibodies?

The determination of the host species may impact the stability and affinity of the discovered VHH antibodies, which could have a mixed influence on their efficacy in downstream applications such as diagnostics, therapeutics, and research tools. Furthermore, species-specific post-translational modifications or glycosylation patterns may influence the functional performance of the VHHs.

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