In silico analysis of different signal peptides to discover a panel of appropriate signal peptides for secretory production of Interferon-beta 1b in Escherichia coli.

Signal peptides (SPs) are one of the most important factors for suitable secretion of the recombinant  heterologous proteins in Escherichia coli (E. coli). The objective of this study was to identify a panel of signal peptides (among the 90 biologically active SPs) required for the secretory production of interferon-beta 1b (IFN-beta 1b) recombinant protein into the periplasmic space of E. coli host. In the initial step, after predicting the accurate locations of the cleavage sites of signal peptides and their discrimination scores using SignalP 4.1 server, 31 SPs were eliminated from further analysis because their discrimination scores were less than 0.5 or their cleavage sites were inappropriately located. Therefore, only 59 SPs could be theoretically applied to secrete IFN-beta 1b into the periplasmic space of E. coli. The physico-chemical and the solubility properties, which are necessary parameters for selecting appropriate SPs, were predicted using ProtParam and SOLpro servers using the 59 remaining signal peptides. The final subcellular localization of IFN-beta 1b in combination with different SPs was predicted using ProtComB server. Consequently, according to the ranking of 59  confirmed SPs, the obtained results revealed that SPs Flagellar P-ring protein (flgI), Glucan 1,3-beta-glucosidase I/II (EXG1) and outer membrane protein C (OmpC) were theoretically the most potent and desirable SPs for secretion of recombinant IFN-beta 1b into the periplasmic space of E. coli. For further studies in the future, the experimental investigations on the obtained results will be considered.

An Albumin-Free Formulation for Escherichia coli-Derived Interferon Beta-1b with Decreased Immunogenicity in Immune Tolerant Mice.

Human serum albumin (HSA)-free formulation of Escherichia coli-derived human interferon beta (IFNß-1b) with a high percentage of monomeric protein and low immunogenicity is developed and characterized in the current study. UV spectroscopy, fluorescence spectroscopy, dynamic light scattering, sodium dodecyl sulfate polyacrylamide gel electrophoresis, Western blotting, Micro-Flow Imaging, resonant mass measurement, size exclusion, and reversed-phase high performance liquid chromatographies were applied to assess the effect of excipients on the stability of IFNß-1b to establish a HSA-free formulation. The antiviral activity of IFNß-1b was evaluated using human lung carcinoma cell line. Immune tolerant mice to hIFNß were used to assess the immunogenicity of the HSA-free formulated IFNß-1b in comparison to Betaferon drug product and Avonex drug substance as standards through IgG titering of plasma. HSA-free formulated IFNß-1b, including 200 mM L-arginine, 200 mM trehalose, and 0.1% n-dodecyl ß-D-maltoside in 10 mM sodium acetate buffer, pH 7.4, showed the highest biological activity. The stability of IFNß-1b in the HSA-free formulation was monitored for 3 weeks at 4°C and 37°C with relative humidity of 10% and 75%, respectively. Protein aggregation and immunogenicity in transgenic mice were decreased in the HSA-free formulated IFNß-1b compared to Betaferon. The stability, biological activity, and immunogenicity of the HSA-free formulation and Betaferon were evaluated. Incubation of formulations at 4°C and 37°C for 3 weeks showed that the HSA-free formulated IFNß-1b was more stable and less immunogenic in transgenic FVB/N mice. Low immunogenicity and the absence of HSA, which reduces the potential risk of viral infection (eg, HIV and HCV), are promising for clinical studies.

[Solubilization Specificities Interferon beta-1b from Inclusion Bodies].

A new solubilization method of recombinant interferon beta-1b (IFNß-1b) from the inclusion bodies was developed. This method allows to extract the target protein selectively in the solutions of different alcohols, such as ethanol, propanol and isopropanol. It was shown that the more effective IFNß-1b solubilization was achieved in the 55% propanol solution. This method allowed to extract the target protein from inclusion bodies around 85-90%, and significantly reduced Escherichia coli content in the solubilizate, in comparison with standard methods.