Antibody Research

Infectivity of SARS-CoV-2 is regulated by three sites on the spike protein: a receptor binding motif (RBM), a subunit (S)1/S2 cleavage site acted upon by the host protease furin, and an S2’ cleavage site acted upon by host protease TMPRSS2. The RBM of the spike protein binds to angiotensin converting enzyme 2 (ACE2) that is highly expressed in cells of the lower respiratory tract. Cleavage of the S1/S2 site by furin liberates a RRAR sequence that is C-terminal in the S1 domain that subsequently binds to neuropilin-1 receptors expressed in respiratory and olfactory epithelial cells. Additionally, cleavage at the S1/S2 site enables a structural change that allows further proteolytic processing by TMPRSS2 that is essential for membrane fusion.

Multipass transmembrane and multimeric membrane proteins are targets for the development of therapeutic monoclonal antibodies, but they present challenges for antibody generation. Membrane proteins represent ~25% of the entire genome and the majority of those are multi-pass, complex proteins that are challenging to express in a native, bio-active state with appropriate quaternary structure.

Conditioned media from cultured cells have long been used to increase the cloning efficiency, growth rate and antibody secretion of hybridomas. The potential sources of conditioned media include cultured splenocytes, peritoneal macrophages, and macrophage, endothelial or fibroblast cell lines. The conditioned media from these cultures contain a variety of cytokines that act as growth factors for hybridomas. However, the constituents of conditioned media are largely undefined. Conditioned media may contain cell metabolites, cellular contaminants, and other undefined components that may interfere with the bio-analysis of hybridoma-derived antibodies.

Infectivity of SARS-CoV-2 is regulated by three sites on the spike protein: a receptor binding motif (RBM), a subunit (S)1/S2 cleavage site acted upon by the host protease furin, and an S2’ cleavage site acted upon by host protease TMPRSS2. The RBM of the spike protein binds to angiotensin converting enzyme 2 (ACE2) that is highly expressed in cells of the lower respiratory tract. Cleavage of the S1/S2 site by furin liberates a RRAR sequence that is C-terminal in the S1 domain that subsequently binds to neuropilin-1 receptors expressed in respiratory and olfactory epithelial cells. Additionally, cleavage at the S1/S2 site enables a structural change that allows further proteolytic processing by TMPRSS2 that is essential for membrane fusion.

Recent studies have suggested a link between the growth of cysts found in the lungs of patients with lymphangioleiomyomatosis (LAM) and elevated levels of vascular endothelial growth factor (VEGF)-C and VEGF-D. The cysts found in LAM patients are lined with cells that are of lymph origin which express and respond to VEGF-C and VEGF-D, which act as primary lymphangiogenic growth factors. Further, LAM patients have dramatically elevated serum levels of VEGF-D, up to one hundred times those of healthy women. Elevated levels of VEGFD in combination with lung cysts are diagnostic for LAM. Inhibiting the actions of VEGF-C and/or VEGF-D, using antibodies, are a potential therapeutic treatment for LAM.

"Using a Molecular Modeling Platform to Guide Therapeutic Antibody Discovery” details the integration of advanced 3-D modeling tools for the analysis of proteins and antibody-antigen interactions in our discovery platform. We show that adding molecular 3D modeling to the mix can reduce the cost and time of antibody discovery. 

Immunization of transgenic animals producing human antibodies is the most successful approach to obtaining fully human therapeutic antibodies. They allow for the rapid generation of candidate antibodies and the ability to transition lead candidates to clinical development without undergoing time-consuming steps such as the humanization of murine antibodies or the affinity maturation of antibodies from structural display libraries.

Hybridoma cell lines have historically offered an efficient, low-cost means to produce large numbers of monoclonal antibodies. However, there are reasons that warrant recombinantly expressing an antibody at a preclinical, R&D stage. These reasons include the need to express antibodies from primary B cells, a surface display library, convert chimeric antibodies to fully human antibodies, humanization of rodent antibodies, and isotype switching. We have developed a recombinant expression system for drug discovery with the ability to express a large number of recombinant antibodies in a timely, cost-efficient manner.

Immunization of transgenic animals producing human antibodies is by far the most successful approach to obtaining “fully human” therapeutic antibodies. They allow for the rapid generation of candidate antibodies and the ability to transition lead candidates to clinical development without undergoing time consuming steps such as humanization or affinity maturation of antibodies from structural display libraries. In collaboration with Harbour Biomed and utilizing transgenic Harbour H2L2TM mice, Antibody Solutions has generated therapeutic human monoclonal antibody candidates against an immune checkpoint membrane protein target, designated “HBM-1”.

Antibody Solutions performed its first program in OmniAbTM animals in September of 2012. In our 6.5 year history with OminAb animals we have worked with >1000 animals for 27 clients. The purpose of this poster is to update Antibody Solutions history of work with OmniAb animals with an emphasis on work performed in