Press release:

Bioxtal aquired new "Cytobody" technology enabeling to fulfill unmet needs in function determination of multi-domain proteins in cell signalling pathways.

Bio-Xtal signed a licence agreement with CNRS / Inserm / Université de Strasbourg on its cyto-soluble recombinant ScFv (Single chain variable fragments) library called Cytobody™(1).

The Cytobody™ library was developed by Prof Weiss and Dr. Martineau on a ScFv scaffold optimised by directed evolution for maximising cytoplasmic expression. As opposed to most randomised libraries developed on an antibody scaffold, the cytobodies are expressed in a soluble and stable state without disulphide bonds. Furthermore, the library was cleared from all non expressed fragments resulting in fast selection of wide variety of highly expressed Cytobodies against any antigen.

An attractive application of such a tool is the study of cell signaling pathways. The high specificity and affinity of cytobodies allows to efficiently block protein-protein interaction in the cell and in animal models. It also limits the off-target effects frequently found with enzyme inhibitors and RNAi.

A first proof of concept was obtained by Dr. Dariavach and Dr Martineau on an important target involved in inflammation: the spleen tyrosin kinase "Syk". Instead of blocking the kinase catalytic activity of Syk, Dr. Dariavach and Dr Martineau discovered a new site between the two SH2 domains of the protein allowing a specific shutdown of mast cells degranulation pathway (2).

Bio-xtal will propose cytobody's selection and characterization services from January 2011 including activity assays, and structure resolution of Cytobody™/antigen complexes. Etienne L’Hermite Bio-xtal’s president declared “Besides applications in cell signalling, the combination of the Cytobody™ technology and our know-how in membrane receptors purification will lead to numerous exiting developments.”

Reference publications:

(1) A focused antibody library for selecting scFvs expressed at high level in the cytoplasm BMC Biotechnology 2007, 7:81
Pascal Philibert, Etienne Weiss, Pierre Martineau etal.

(2) A novel drug like spleen tyrosine kinase binder prevents anaphylactic shock when administered orally. The Journal of Allergy and Clinical Immunology (2008) 122: 188-194.
Pierre Martineau, Piona Dariavach et al.