Isolation of HuIFN-beta by immunosorbent and high-pressure liquid chromatography

Inclusion bodies and purification of proteins in biologically active forms

Even though recombinant DNA technology has made possible the production of valuable therapeutic proteins, its accumulation in the host cell as inclusion body poses serious problems in the recovery of functionally active proteins. In the last twenty years, alternative techniques have been evolved to purify biologically active proteins from inclusion bodies. Most of these remain only as inventions and very few are commercially exploited. This review summarizes the developments in isolation, refolding and purification of proteins from inclusion bodies that could be used for vaccine and non-vaccine applications. The second section involves a discussion on inclusion bodies, how they are formed, and their physicochemical properties. In vivo protein folding in Escherichia coli and kinetics of in vitro protein folding are the subjects of the third and fourth sections respectively. The next section covers the recovery of bioactive protein from inclusion bodies: it includes isolation of inclusion body from host cell debris, purification in denatured state alternate refolding techniques, and final purification of active molecules. Since purity and safety are two important issues in therapeutic grade proteins, the following three sections are devoted to immunological and biological characterization of biomolecules, nature, and type of impurities normally encountered, and their detection. Lastly, two case studies are discussed to demonstrate the sequence of process steps involved.

Purification of recombinant human interferon-beta by immobilized antisense peptides

Synthetic antisense peptides encoded in the antisense strands of DNA corresponding to the 1-14, 42-54 and 103-115 fragments of the human interferon-beta sequence were applied in the purification of recombinant human interferon-beta from a mammalian cell culture. The protein fragments were selected on the basis of their computer-predicted exposure on the surface of the protein. The antisense peptides were synthetized by the solid-phase method directly on the resin used as the stationary phase in affinity chromatography. All the tested antisense peptides showed a selective affinity for human interferon-beta, permitting a ten-fold purification of the protein.

Highly sensitive enzyme immunoassay of human interferon-beta 1

A highly sensitive sandwich enzyme immunoassay for human interferon-beta 1 (HuIFN-beta 1) was developed. HuIFN-beta 1-containing samples and horseradish peroxidase (HRP)-labeled mouse anti-HuIFN-beta 1 monoclonal antibody (Fab') were incubated overnight at 2-10 degrees C in the wells of a 96-well microtiter plate, onto which affinity-purified rabbit anti-HuIFN-beta 1 polyclonal antibody was coated. The EIA was able to detect 0.5 IU/ml of HuIFN-beta 1, thus showing higher sensitivity than bioassay. The values obtained by the EIA closely paralleled those obtained by bioassay in the concentration which bioassay can detect. In order to detect the concentration below 0.5 IU/ml of HuIFN-beta 1, the avidin/biotin-amplified EIA was also developed. The use of biotinylated mouse anti-HuIFN-beta 1 monoclonal antibody (F(ab')2) and HRP-avidin in the EIA made it possible to detect 0.1 IU/ml of HuIFN-beta 1. These EIAs were applied for the studies such as process control of HuIFN-beta 1 production, pharmacokinetics of HuIFN-beta 1, and determination of serum level of HuIFN-beta 1 in healthy subjects.

Detection of high levels of immunoreactive human beta-1 interferon in sera from HIV-infected patients

We have examined human interferon beta-1 (HuIFN-beta 1) levels in the sera from patients with various diseases by using a newly developed highly sensitive enzyme-linked immunosorbent assay system (ELISA). High levels of HuIFN-beta 1 were detected in the sera from Human Immunodeficiency Virus-I (HIV-I) infected patients, especially of asymptomatic carriers. The serum level of HuIFN-beta 1 may be a good indicator of HIV-I infection and of other immunological disorders.

Preparative reversed-phase high-performance liquid chromatography of iodinated insulin retaining full biological activity

Insulin monoiodinated in Tyr A14, A19, B16 and B26 can be separated from insulin and diiodoinsulins using reversed-phase high-performance liquid chromatography on LiChrosorb RP-18 columns. Monoiodoinsulins with high and low specific activities were isolated from a number of buffer systems without any reduction in binding affinity and biological activity in isolated rat fat cells. The reason for the previously observed reduction in the binding affinity was probably column bleeding, i.e., chemical degradation of the column support.