Human scFv and Fab Naïve Libraries
Naïve human libraries containing billions of antibodies for the discovery of human IgGs can be accessed for antibody discovery programs. Antibodies are expressed in bacteria in either an scFv or Fab format and can be rapidly configured into IgG for expression in mammalian cell lines. The variable region genes (V genes) that have been derived from IgM heavy (VH) and light chain (VL) gene sequences from naïve human donors using both peripheral human blood and tonsil as source material.
Our human Fab libraries contain over 10 billion antibodies for the discovery of human IgGs. These human Fab libraries are a complementary approach to the human single chain variable fragments (ScFvs) libraries. Compared to scFvs, Fabs are much less prone to aggregation issues and loss of activity when formatting to IgG. Moreover, the monovalent display of a Fab results in a truly 1:1 interaction without any avidity involved for monomeric antigens. Therefore, the antibody format of choice of the human Fab library is a key feature for the successful isolation of human antibodies with desired target specificities and properties.
Our human scFv phage display libraries allow the rapid selection of antibodies with high affinity and specificity. Furthermore, scFv antibodies are well suited for technologies in which a single chain antibody fragment is needed (e.g. CART). Antibodies are expressed in bacteria in an scFv format and can be rapidly configured into IgG or Fab format for expression in mammalian cell lines. Typically, the libraries show 99% of scFv having both VH and VL inserts with over 80% of clones expressing full length in-frame scFv. Consequently, the libraries are very large with rich diversity and are ideal for screening all antigen types for selection of functional and high affinity antibodies.
Llama VHH Naïve Library
The use of single domain antibody libraries generated upon immunization of llamas has proved to be a very valid method for the isolation of highly specific binders. Nevertheless, immunizations have drawbacks and may not be appropriate in certain cases e.g. where availability of the antigen is limited, antigen is toxic, immunodominant epitopes exist. An effective alternative is to bypass the immunization and use a naïve library of llama single domain antibodies. We have generated several llama VHH Naïve libraries using biological samples from over 20 different animals that can be selected against virtually any antigen. The 1.5E09 size library has been validated and delivered anti human CXCR4 and anti HER2 VHHs with low nM EC50 values.
Llama VHH-huFc Naïve Library
Using the proprietary triple vector system (as described below) we have generated a Llama VHH-huFc Naïve Library using biological samples from eight different animals that can be selected against virtually any antigen. The 1.3E09 size library has been validated and delivered anti-human CXCR4 VHH-huFc molecules with pM EC50 values.