Phage and Gram-positive bacterial display of human antibody repertoires enables isolation of functional high affinity binders

• Surface display couples genotype with a surface exposed phenotype and thereby allows for screening of gene-encoded protein libraries for desired characteristics. Of the various display systems, phage display is by far the most popular, mainly thanks to its ability to harbor large library sizes. Here, we describe the first use of a grampositive host for display of a library of human antibody genes. The method allows for swift generation of binders by combining phage and gram-positive display, for its ease of use for screening, sorting and ranking by flow cytometry. We demonstrate the utility of this method by identifying specific low nanomolar scFv towards human HER2. The ranking and performance of the scFv isolated by flow sorting in surface immobilized form was retained when expressed as soluble scFv and analyzed by biolayer interferometry as well as after expression as full-length antibodies in mammalian cells. We also show the possibility to use gram-positive display to directly improve the affinity of the identified binders via an affinity maturation step using random mutagenesis and flow sorting. We believe this combined approach has the potential for a more complete scan of the antibody repertoire and for swift affinity maturation of human antibody formats.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik -- Annan industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology -- Other Industrial Biotechnology (hsv//eng)

Nyckelord

S.carnosus

Flow cytometry

Antibody

HER2

phage display

cell-surface display

affinity maturation

Bioteknologi

Biotechnology

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