From cloning to a commercial realization: human alpha interferon

Interferon lambda protects cattle against bovine viral diarrhea virus infection

Interferon lambda (IFN-λ) plays an important role in inducing an antiviral state in mucosal surfaces and has been used as an effective biotherapeutic against several viral diseases. Here we performed a proof of concept study on the activity of a biologically active recombinant bovine IFN-λ (rIFN-λ) produced in eukaryotic cells against Bovine Viral Diarrhea Virus (BVDV) in cattle. We first confirmed the lack of toxicity of different concentrations of rIFN-λ in bovine peripheral blood cells and the safety of its subcutaneous application in calves in doses up to 12 IU/kg. The antiviral activity of the rIFN-λ against BVDV was assessed in calves that were inoculated with 6 IU/kg of rIFN-λ (n = 4) or mock-treated (n = 2) two days before and after challenge with a BVDV type-2 non-cytopathic strain. Mock-treated animals developed respiratory disease, shedded the virus from 4 to 7 days post-infection (dpi) and had viremia between 4 and 14 dpi. Conversely, calves treated with rIFN-λ did not develop clinical symptoms. The virus was not found in nasal secretions or sera. Only one animal had a positive viral RNA detection in serum at 7 dpi. All infected animals treated with rIFN-λ increased systemic type-I IFNs levels at 4 dpi. The antiviral treatment induced an earlier onset of the anti-BVDV neutralizing antibodies. Altogether, these results constitute the proof-of-principle of bovine IFN-λ as an antiviral biotherapeutic to protect cattle against the clinical disease caused by BVDV.

Principles of Immunotherapy: Implications for Treatment Strategies in Cancer and Infectious Diseases

The advances in cancer biology and pathogenesis during the past two decades, have resulted in immunotherapeutic strategies that have revolutionized the treatment of malignancies, from relatively non-selective toxic agents to specific, mechanism-based therapies. Despite extensive global efforts, infectious diseases remain a leading cause of morbidity and mortality worldwide, necessitating novel, innovative therapeutics that address the current challenges of increasing antimicrobial resistance. Similar to cancer pathogenesis, infectious pathogens successfully fashion a hospitable environment within the host and modulate host metabolic functions to support their nutritional requirements, while suppressing host defenses by altering regulatory mechanisms. These parallels, and the advances made in targeted therapy in cancer, may inform the rational development of therapeutic interventions for infectious diseases. Although "immunotherapy" is habitually associated with the treatment of cancer, this review accentuates the evolving role of key targeted immune interventions that are approved, as well as those in development, for various cancers and infectious diseases. The general features of adoptive therapies, those that enhance T cell effector function, and ligand-based therapies, that neutralize or eliminate diseased cells, are discussed in the context of specific diseases that, to date, lack appropriate remedial treatment; cancer, HIV, TB, and drug-resistant bacterial and fungal infections. The remarkable diversity and versatility that distinguishes immunotherapy is emphasized, consequently establishing this approach within the armory of curative therapeutics, applicable across the disease spectrum.

Soluble Prokaryotic Expression and Purification of Human Interferon Alpha-2b Using a Maltose-Binding Protein Tag

Human interferon alpha-2b (IFNα-2b) has therapeutic applications as an antiviral and antiproliferative drug and has been used for a wide range of indications. Efficient production of IFNα-2b in Escherichia coli has been difficult because the protein tends to form inclusion bodies. This obstacle has garnered interest in efficiently expressing IFNα-2b and overcoming its poor solubility. In this study, seven N-terminal fusion partners - hexahistidine (His6), thioredoxin, glutathione S-transferase (GST), maltose-binding protein (MBP), N-utilization substance protein A, protein disulfide bond isomerase (PDI), and b'a' domain of PDI - were tested for soluble overexpression of codon-optimized IFNα-2b in E. coli. Low temperature increased the expression level of all of the tagged proteins except for the GST fusion. All the tags, except for His6 and GST, improved solubility. We purified IFNα-2b from the MBP-tagged fusion using immobilized metal affinity chromatography and anion exchange chromatography, and obtained a final yield of 7.2 mg from an initial 500-ml culture. The endotoxin level was 0.46 EU/µg. Biological activity was demonstrated using a luciferase assay, which showed a dose-dependent response with a calculated EC50 of 10.3 ± 5.9 pM. Our results demonstrate that using an MBP-tagged fusion is an efficient way to produce pure IFNα-2b.

A strategy for high-level expression of soluble and functional human interferon alpha as a GST-fusion protein in E. coli

Escherichia coli is the most extensively used host for the production of recombinant proteins. However, most of the eukaryotic proteins are typically obtained as insoluble, misfolded inclusion bodies that need solubilization and refolding. To achieve high-level expression of soluble recombinant human interferon alpha (rhIFNalpha) in E. coli, we have first constructed a recombinant expression plasmid (pGEX-hIFNalpha2b), in which we merged the hIFNalpha2b cDNA with the glutathione S-transferase (GST) coding sequence downstream of the tac-inducible promoter. Using this plasmid, we have achieved 70% expression of soluble rhIFNalpha2b as a GST fusion protein using E. coli BL21 strain, under optimized environmental factors such as culture growth temperature and inducer (IPTG) concentration. However, release of the IFN moiety from the fusion protein by thrombin digestion was not optimal. Therefore, we have engineered the expression cassette to optimize the amino acid sequence at the GST-IFN junction and to introduce E. coli preferred codon within the thrombin cleavage site. We have used the engineered plasmid (pGEX-Delta-hIFNalpha2b) and the modified E. coli trxB(-)/gor(-) (Origami) strain to overcome the problem of removing the GST moiety while expressing soluble rhIFNalpha2b. Our results show the production of soluble and functional rhIFNalpha2b at a yield of 100 mg/l, without optimization of any step of the process. The specific biological activity of the purified soluble rhIFNalpha2b was equal to 2.0 x 10(8) IU/mg when compared with the WHO IFNalpha standard. Our data are the first to show that high yield production of soluble and functional rhIFNalpha2b tagged with GST can be achieved in E. coli.

Construction, expression and characterization of human interferon α2b-(G4S)n-thymosin α1 fusion proteins in Pichia pastoris

AIM: Interferon α2b (IFNα2b) and thymosin α1 (Tα1) exhibit synergic effects in the treatment of hepatitis B and hepatitis C when used together. For developing a fusion protein drug, fusion proteins of IFNα2b and Tα1 linked by different lengths of (G4S)n (n = 1-3) were constructed and expressed in Pichia pastoris.

METHODS: Using PCR and molecular clone techniques, the fusion genes of IFNα2b-(G4S)n-Tα1 (n = 1-3) were constructed and subcloned into the eukaryotic expression vector pPIC9. After transformation of these plasmids into P. pastoris, the expressed fusion proteins IFNα2b-(G4S)n-Tα1 (n = 1-3) were obtained. These proteins were purified through diethylaminoethyl (DEAE) affinity chromatography and Superdex™ 75 gel filtration and analyzed by SDS-PAGE and Western blot. Antiviral and E-rosette assays were used to investigate the bioactivities of these fusion proteins.

RESULTS: DNA sequencing confirmed that the fusion genes of IFNα2b-(G4S)n-Tα1 (n = 1-3) were correctly cloned to the pPIC9 vector. The recombinant IFNα2b-(G4S)n-Tα1 (n = 1-3) fusion proteins expressed in P. pastoris were purified with DEAE and Superdex™ 75 gel filtration chromatography. The fusion proteins could be observed on sodium dodecylsulfate-polyacrylamide gel electrophoresis with molecular weight (MW) of 23.2, 22.9, and 22.6 ku, respectively, and reacted to the IFNα2b monoclonal antibody and Tα1 polyclonal antibody. The purified fusion proteins exhibit antiviral activity and can enhance the percentage of E-rosette-forming-cell in E-rosette assay.

CONCLUSION: The recombinant IFNα2b-(G4S)n-Tα1 (n = 1-3) fusion proteins were successfully expressed in P. pastoris. Purified fusion proteins exhibit both antiviral activity of IFNα2b and immunomodulatory activity of Tα1 in vitro. These results will be the basis for further evaluation of the fusion proteins’ function in vivo.

Inhibition of growth, transformation, and expression of human papillomavirus type 16 E7 in human keratinocytes by alpha interferons

We used a model system of normal human keratinocytes (HKc) and HKc immortalized with human papillomavirus type 16 DNA (HKc/HPV16) to investigate the effects of alpha interferons (IFN-alpha) on the growth of HPV16-immortalized human epithelial cells, on HPV16-mediated immortalization of normal HKc, and on HPV16 gene expression. Normal HKc and HKc/HPV16 were treated with several recombinant human IFN-alpha subtypes (IFN-alpha B, IFN-alpha D, and IFN-alpha B/D). These IFN-alpha subtypes inhibited proliferation of both normal HKc and HKc/HPV16 in a dose-dependent fashion; however, although 1,000 to 10,000 U of IFN-alpha per ml were required to inhibit growth of normal HKc, HKc/HPV16 were substantially growth inhibited by 100 U/ml. In addition, 100 U of IFN-alpha B/D per ml inhibited transformation of normal HKc by HPV16 DNA. Northern (RNA) blot analysis showed no effect of IFN-alpha on the mRNA levels of the HPV16 E6 and E7 open reading frames. However, immunofluorescence studies of the HPV16 E6 and E7 proteins with anti-E6 and anti-E7 monoclonal antibodies showed significant inhibition of E7 protein expression in cells treated with IFN-alpha, whereas E6 protein expression was not altered. The inhibition of E7 protein expression in cells treated with IFN-alpha was further confirmed by Western immunoblot analysis. These results suggest that IFN-alpha may inhibit HPV16-mediated transformation of HKc and proliferation of HKc/HPV16 through an inhibition of HPV16 E7 protein expression.