Select the Best-Fit Host Species for sdAb Discovery
Equipped with the world-leading sdAb development platform and professional scientific staffs, Creative Biolabs is proud to support high-efficiency sdAb development projects for our customers all over the world. Compared with conventional IgG, single domain antibody presents better properties, such as smaller size and higher penetrability, which has become one of the most promising candidates for drug discovery and other applications. Currently, our scientists can generate novel sdAbs from different species, including llama, alpaca, camel, and even shark.
Llama
Like all members of the camelid family, the llama antibodies have three IgG subclasses which are the conventional IgG1, and the non-conventional IgG2 and IgG3. Compared with the IgG1, there is a splicing defect in the CH1 exon which results in the absence of the CH1 domain in both IgG2 and IgG3. What’s more, many camel VHH sequences contain an extra pair of Cys residues in the H1 and H3 loops, which form an interloop disulfide bond. However, the frequency of this additional disulfide bond is relatively low in llama, but its H3 loop is significantly shorter than camel VHH.
Alpaca
The alpaca is a species of South American camelid which is always 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. The alpaca sera IgG consists of almost 50% heavy chain only antibodies (HCAbs), most 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, the camel 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 makes up the remainder. Compared with the South American camelid species, the percentage of HCAbs in the blood of camels is significantly higher, ranging from 50% to 80%.
Shark
As one typical species of cartilaginous fishes, 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 consists of five constant domains and one variable region (VNAR). VNAR has been served as a wonderful source for the development of sdAbs. Relative to the HCAbs in Camelidae, the shark IgNARs are slightly at a lower level, reaching 5% of the total Igs in the blood.
Along with rich experience in sdAb development, Creative Biolabs now can provide 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.
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