A high yielding IFNAR1 ECD mammalian expression process for use in autoimmune disease drug development.

Interferon-alpha receptor 1 (IFNAR1) is a target of interest for recombinant biotherapeutics that block the JAK/STAT pathway. This pathway is believed to play a role in many diseases including Hepatitis B and C, Herpes Simplex, Multiple Sclerosis, and other autoimmune disorders. By using IFNAR1 as a target to block Type I IFN from binding to the JAK/STAT pathway and prevent activation of this target, autoimmune disease progression can be modulated. Current IFNAR1 extracellular domain (ECD) expression and purification protocols are labor intensive with low product yield and limited scalability. In this work, we evaluate three different expression systems (baculovirus, human embryonic kidney 293 (HEK293×), and Chinese hamster ovary (CHO)) to improve expression of IFNAR1 ECD. We demonstrate the benefits of utilizing mammalian CHO cell transient transfection to increase expression titer, as well as an improved two-step purification process performed using immobilized metal affinity chromatography (IMAC) as the capture step and Ceramic Hydroxyapatite (CHT) Type II for HMW impurity removal in flow through mode. This process showed an 20-fold increase in productivity compared to the baseline process as measured by grams purified per liter of cell culture fluid. Lastly, the improved process showed good scalability, enabling efficient purification of 3.6 g of product from a 30 L scale bioreactor.

Molecular characterization of feline type I interferon receptor 2.

The cDNA sequence of feline interferon receptor 2 (feIFNAR2) was generated using RT-PCR method in present study. This gene included 1,572 bp and encoded a 523 aminoacid (aa) protein with a 35 aa signal peptide. The deduced protein shared 61% amino acid identity to the human IFNAR2. There were two fibronectin type III (FBN-III) domains of about 110 residues in the extracellular domain. Homology modeling of feIFNAR2 presented a similar structure with other IFN receptors. The ELISA and FACS experiments demonstrated that the protein could bind to feIFN-alpha or feIFN-omega. However, antiviral activity assay found that feIFN-omega had broader species spectrum compared with feIFN-alpha. To define the functional differences, several point mutations of feIFNAR2 were constructed and the relative affinities of feIFN-alpha or feIFN-omega for feIFNAR2 and mutants were evaluated. The results suggested that feIFN-alpha and feIFN-omega had different binding sites on feIFNAR2. T75 and M77 on feIFNAR2 were hotspots for binding to feIFN-alpha, but not to feIFN-omega. These findings suggested that the cloned feline IFNAR2 interacted with both feIFN-alpha and feIFN-omega, however, not sharing the same binding sites.