Technology

VHH libraries

At QVQ we offer services with immune-, non-immune-, synthetic- and combinatorial sdAb libraries.

Immune libraries

QVQ has experience with a large variety of antigens, such as purified natural and recombinant proteins and more complex samples like cells and tissues. QVQ collaborates with well-accredited CROs for immunizations which are conducted according to the applicable animal welfare act at place. All immunizations are reviewed by the internal animal experiment commission. After the immunization, we always determine titers of antigen-specific antibodies in sera by ELISA or flow cytometry.

Next, VHH gene regions are picked up by PCR from reverse-transcribed RNA from PBMCs and cloned into our proprietary phagemid vectors. In our phagemid vector, the VHH genes are fused to a C-terminal tag and the bacteriophage coat protein pIII. QVQ’s immune libraries contain on average 10^8 transformants with ~100% correct insert frequency.

Ready-to-use libraries

Pooled
>100 animals
∼ 10¹¹ transformants

Synthetic
>1500 unique, good-producing sdAbs
Theoretical div. 10³⁰

– the large pooled sdAb library

To allow immediate panning at QVQ without immunizations, we generated a large, pooled library (QPoLi) from >100 different immune libraries that contains ~10¹¹ sdAb-phagemid transformants. QVQ has dedicated protocols for working with libraries with large diversity.

– a VH3-3-based synthetic sdAb library

Based on over a decade of VHH sequence experience, QVQ designed a synthetic library (QSyLi) that resembles the most prominent VHH germline (VH3-3) with germline-matched diversifications of both frameworks and CDRs. This germline is characterized by a long, kinked CDR3, which results in a relatively large paratope and good binding affinities. In addition, to facilitate large-scale purification of lead clones later, we have incorporated protein A binding sequences in the frameworks.

Synthetic libraries can also be designed and generated for other VHH germlines. QVQ can custom-design and generate synthetic variant phagemid libraries for your sdAb of choice.