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Tetrahymena offers industry-first alternatives to current manufacturing practices (TetraExpress™; PRISM™) that are particularly amenable to the production of difficult to express eukaryotic proteins including fully assembled heavy and light chain antibodies, viral and protozoan surface antigens, single and multispan membrane proteins, and multi-subunit enzymes. Such proteins have numerous applications in therapeutic drug development; diagnostics, human and animal vaccine development; structure-based drug design, and industrial enzyme production.
Monoclonal antibodies (mAbs) are the fastest growing class of therapeutic recombinant protein due to their exquisite specificity, and their wide-ranging applications in the treatment of autoimmune disease, cancer, infectious disease and inflammation. Long restricted to production in mammalian tissue culture cells, expression of full-length tetrameric antibodies in microbial systems has been hampered by low yields, protein folding difficulties (in bacteria), and addition of non-human post-translational modifications (in yeast). Having none of these drawbacks, Tetrahymena is a powerful alternative to more conventional hosts with the potential to 1) greatly accelerate the identification of lead therapeutic candidates; 2) provide a scalable platform for the production of therapeutic and diagnostic antibodies; and, 3) increase access to these life-saving drugs by reducing costs. The system has the ability to produce fully assembled and constitutively secreted H+L chain mAbs at yields that greatly surpass those reported in other microbial systems. A major strength of this system with regard to mAb production is its ability to produce both aglycosylated and uniformly glycosylated biologics.
Relative to conventional microbial systems, Tetrahymena offers distinct advantages for the production of recombinant subunit vaccines for the prevention of human and animal disease. Being a eukaryote, it produces correctly folded membrane and secreted proteins, a key requirement for vaccine efficacy, given that the preponderance of neutralizing antibodies are directed at conformational epitopes on their targets. Bacterial platforms often fail to meet this requirement. Second, with a surface membrane that is greatly expanded by cilia, and with no cell wall (as in bacteria and yeast), Tetrahymena produces high yields of prospective subunit antigens that are readily purified. Finally, expression of subunit antigens in the context of PRISM™ – a naturally occurring immunostimulatory matrix - has the potential to significantly increase potency even in the absence of adjuvants, and offers an entirely new approach to the production of multivalent and combinatorial vaccines against new and emerging pathogens. Preclinical trials have demonstrated the utility of T. thermophila for the manufacture of effective vaccines against viral and protozoan pathogens.
Recombinant enzymes have become indispensable in many industrial settings ranging from food and agriculture processes to biofuel production. For many industrial processes the costs of enzymes represent the single largest expense associated with production. Therefore, decreasing enzyme costs through generation of high-yield cell lines and economies of scale can have a substantial positive impact on industrial production costs. Highlighting the opportunity Tetrahymena offers in this space, a recent benchmarking study found that T. thermophila can produce a commercially available serine protease via the constitutive secretory pathway at 21-fold higher yield and with comparable specific activity compared to the currently used yeast expression platform.
Membrane proteins play critically important roles in a vast number of cellular processes. Despite this, and despite the fact that such proteins comprise roughly ~70% of all drug targets currently under development by the pharmaceutical industry, they are remarkably understudied in terms of their 3-dimensional structures. Indeed, only ~1% of the roughly 10,000 predicted membrane proteins encoded by the human genome have unique structures assigned to them. This is a major impediment for rational drug design, and is in large part due to the inability of current systems to provide sufficient amounts of recombinant protein for X-ray crystallography and NMR. Recent studies at Tetragenetics demonstrate the unique potential of the TetraExpress™ system to produce a wide range of eukaryotic membrane proteins including GPCRs, receptor tyrosine kinases, glutamate receptors, protein modifying enzymes, multisubunit vaccine antigens, and GPI-anchored proteins at the 5-100 mg/L scale with near uniform N-glycosylation. We are working with our clients in industry, academics and government to make the TetraExpress™ platform an essential part of their structural biology toolkit.
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