Custom llama polyclonal antibodies

Llama

Covalab, it’s 20 years of custom antibody engineering, including development, production, purification and other services. Our scientists have 30 years of experience in immunology, and master the immunisation procedures of many host species.

From now on, we are able to provide antibodies raised in an exclusive additional species thanks to our governmental agreements as well as adapted facilities. Indeed, llamas have phylogenetic characteristics that can help circumvent cross-reactivity issues due to conserved patterns within conventional species. Furthermore, llamas exhibit camelids-specific features that lead to important breakthroughs in scientific and medical research (see section below).

We can also ensure the best project management for the development of your llama antibodies as every step in the development process, including animal breeding, immunisation, bleeds as well as serum purification are performed within our region, in Rhône-Alpes, France. France

About camelids antibodies

Like all mammals, camelids produce conventional antibodies made of 2 heavy chains and 2 light chains bound together with disulphide bonds in a Y shape (IgG1). However, they also produce two unique subclasses of immunoglobulin G, IgG2 and IgG3, also known as heavy chain IgG (hcIgG). These antibodies are made of only two heavy chains 1, that lack the CH1 region but still bear an antigen binding domain at their N-terminus called VHH.

Conventional Ig require the association of variable regions from both heavy and light chains to allow a high diversity of antigen-antibody interactions. Although isolated heavy and light chains still show this capacity 2, 3, they exhibit very low affinity 4 when compared to paired heavy and light chains. The unique feature of hcIgG is the capacity of their monomeric antigen binding regions to bind antigens with specificity, affinity and especially diversity that are comparable to conventional antibodies without the need of pairing with another region.

Heavy chain IgG

This feature is mainly due to a couple of major variations within the amino acid sequence of the variable region of the two heavy chains, which induce deep conformational changes when compared to conventional Ig. Major substitutions in the variable regions 5, 6, 7 prevent the light chains from binding to the heavy chains, but also prevent unbound heavy chains from being recycled by the Immunoglobulin Binding Protein (BiP) 8.

The third Complementarity Determining Region (CDR3) of the variable region of these antibodies has been found to be twice as long as the conventional ones 8. This results in an increased interaction surface with the antigen as well as an increased diversity of antigen-antibody interactions, which compensates the absence of the light chains. Moreover, an additional cysteine residue allow the structure to be more stable, thus increasing the strength of the interaction9.

Advantages of llama antibodies

Very interesting characteristics result from their smaller size.

  • their steric hindrance is reduced, allowing them to reach hardly accessible antigens that conventional antibodies can not, such as active sites of enzymes (useful to inhibit enzyme activity) as well as smaller enzymes, such as lysozymes or ribonucleases.
  • their capacity to penetrate tissues is increased when compared to conventional antibodies, allowing a more precise staining of tissue sections when performing immunohistochemistry.

Furthermore, the high refolding capacity of the VHH region allow them to be thermodynamically more stable and especially to resist to high temperatures (up to 90°C / 194°F) 10, 11, 12, 13 and extreme pH, such as gastric acid 14.

Development and purification of camelid IgG

Animals have been immunised according to our exclusive protocol, using two peptides we have designed and synthesised to mimic the prion protein, and coupled to carrier proteins prior to injection. Serum immunoreactivity has been monitored against both peptides by ELISA. The serum sample showing the best immunoreactivity has been purified by affinity chromatography using protein A (IgG2) or protein G (IgG1 and IgG3) columns. Fractions of purified IgG2 have been subsequently hydrolysed by papain (10 µg/mg of antibody) or pepsin (5 µg/mg of antibody) overnight at 37°C to isolate VHH fragments.

SDS-PAGE

Fractions of purified products have been separated by SDS-PAGE under denaturing conditions using a 10% acrylamide gel and Tris-glycine buffer, and then revealed using silver staining.

  • A: IgG2 fraction
  • B: IgG1 fraction
  • C: IgG3 fraction
SDS-PAGE

Products of digestion by papain or pepsin have been separated by SDS-PAGE under denaturing conditions using a 15% acrylamide gel and Tris-glycine buffer, and then revealed using silver staining.

  • A: Control IgG2 fraction
  • B: Papain digestion products
  • C: Pepsin digestion products

References

  • 1 - Hamers-Casterman C. et al., Naturally occurring antibodies devoid of light chains. Nature 363:446–448 (1993)
  • 2 - Utsumi S. et al., The subunits of purified rabbit antibody. Biochemistry 3:1329–1338 (1964)
  • 3 - Yoo TJ. et al., Specific binding activity of isolated light chains of antibodies. Science 157:707-709 (1967)
  • 4 - Ward ES. et al., Binding activities of a repertoire of single immunoglobulin variable domains secreted from Escherichia coli. Nature 341:544-546 (1989)
  • 5 - Muyldermans S. et al., Sequence and structure of VH domain from naturally occurring camel heavy chain immunoglobulins lacking light chains. Protein engineering 7:1129-1135 (1994)
  • 6 - Vu KB. et al., Comparison of llama VH sequences from conventional and heavy chain antibodies. Protein engineering 7:1129-1135 (1994)
  • 7 - Muyldermans S. et al., Recognition of antigens by single-domain antibody fragments: the superfluous luxury of paired domains. Mol Immunol. 34:1121-1131 (1997)
  • 8 - Muyldermans S. et al., Unique single-domain antigen binding fragments derived from naturally occurring camel heavy-chain antibodies. J Mol Recognit. 12:131-140 (1999)
  • 9 - Desmyter A. et al., Antigen specificity and high affinity binding provided by one single loop of a camel single-domain antibody. J Biol Chem. 276:26285-26290 (2001)
  • 10 - Van der Linden RH. et al., Comparison of physical chemical properties of llama VHH antibody fragments and mouse monoclonal antibodies. Biochim Biophys Acta 1431:37-46 (1999)
  • 11 - Perez JM. et al., Thermal unfolding of a llama antibody fragment: a two-state reversible process. Biochemistry 40:74-83 (2001)
  • 12 - Dumoulin M. et al., Single-domain antibody fragments with high conformational stability. Protein Sci 11:500-515 (2002)
  • 13 - Ewert S. et al., Biophysical properties of camelid V(HH) domains compared to those of human V(H)3 domains. Biochemistry 41:3628-3636 (2002)
  • 14 - Van der Vaart JM. et al., Reduction in morbidity of rotavirus induced diarrhoea in mice by yeast produced monovalent llama-derived antibody fragments. Vaccine 24:4130–4137 (2006)

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