TARGETING THE MOST COMPLEX ANTIGENS

PERFECT ANTIGEN
STRONG IMMUNE RESPONSE

Ciloa’s recombinant exosomes permit the antibody development against the most complex membrane antigens.

Current technologies have to face 4 bottlenecks specific of membrane protein targets; all are unlocked by Ciloa’s technology :

  • Requirement of a perfect antigen
  • Low immunogenicity of membrane antigens
  • Time for antibody hit screening against epitopes in a natural context
  • Difficulty to characterize all interaction parameters of a lead with its membrane protein target.

TECHNOLOGICAL CONSTRAINTS

The antigens necessary to develop monoclonal antibodies that recognize conformational epitopes must exhibit fully native conformation. This is particularly challenging for proteins with multi-transmembrane domains, such as GPCRs.

For the development of new therapies or preventive strategies, it would be fundamental to have membrane proteins in the purest form but still in native conformation and embedded in a membrane. In contrast to soluble proteins that are quite easy to produce, this is very challenging for integral membrane proteins; indeed, they lay on different mutually incompatible environments, i.e. “aqueous-lipidic-aqueous”. The influence of membrane phospholipids on membrane proteins is especially significant. In absence of such specific environments, membrane proteins do not fold properly and consequently are not functional. In addition, most membrane proteins must acquire specific post-translational modifications for their proper folding and several are active as homo- or hetero-oligomers.

The scientific community is well-aware that these specific constraints can be satisfied for human membrane proteins only by expression in human or animal cells. Therefore, most human membrane proteins produced either synthetically, or in E. coli, or yeast, or insect cells do not present a fully native conformation. In addition, membrane proteins produced in human cells extracted by detergents (even when reinserted in liposomes) lose their native conformations.

Until now, the best source of native membrane proteins for the development of antibodies is whole cells expressing these proteins, or membranes purified from these cells, or VLPs (Viral Like Particles containing HIV or MuLV capsids). Unfortunately, the low concentration of  membrane proteins and the high amount of other proteins (like those of viral capsids) are major drawbacks for developing strong and specific immune responses targeting membrane proteins that are generally poor immunogens.

OVERCOME TECHNOLOGICAL LOCKS

1 – PERFECT ANTIGEN

Ciloa’s membrane proteins on exosomes are embedded in a membrane originated from cells with a topology identical to that of the original proteins on cells. This is the sole technology that tailors the most challenging membrane proteins (GPCRs, Ion Channels, Kinase Receptors…) on exosomes :

  • fully native and mature
  • as complexes of homo-oligomers or hetero-oligomers
  • associated with their accessory proteins
2 – IMMUNIZATION

The development of specific immune response is helped by :

  • Exosome functions in natural immune response
  • High concentration of antigen
  • Few contaminants
  • Proteins with fully native conformation
  • Potent immunization methods
3 – HIT SCREENING & LEAD PROFILING

Rapid selection and potent characterization of monoclonal antibody hits by ELISA, SPR (Surface Plasmon Resonance) or cytofluorimetry :

  • No antigen labeling required
  • Screening automation
  • Immediate access to all interaction parameters
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