Highly efficient strategy of lipopolysaccharide (LPS) decontamination from rHBsAg: synergistic effect of enhanced magnetic nanoparticles (MNPs) as an LPS affinity adsorbent (LAA) and surfactant as a dissociation factor.

The interaction of lipopolysaccharide with a recombinant protein is a serious bottleneck, particularly in the purification step of bioprocessing. Recombinant hepatitis B surface antigen (rHBsAg), the active ingredient of the hepatitis B vaccine, is probably contaminated by extrinsic LPS like other biopharmaceuticals. This research intends to eliminate LPS from its mixture with rHBsAg efficiently. Immobilized polymyxin B on magnetic nanoparticles (PMB-MNPs) was synthesized and implemented as an enhanced LPS affinity adsorbent (LAA). The 20-80 EU/dose binary samples with and without surfactant were applied to PMB-MNPs. Formerly, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were examined on the samples to qualitatively show the dissociation effect of the surfactant. Considering the high potential interaction of LPS with HBsAg, the dissociation effects of 0.5 and 1.5% Tween 20 on the binary samples were assessed using immunoaffinity chromatography (IAC) as a quantification tool. The dissociation effect of Tween 20 substantially diminished the interaction, leading to a proportional increase of free LPS up to 66%. The synergetic effect of Tween 20 and privileged LAA was highly effective in eliminating more than 80% of LPS with a remarkable LPS clearance factor of 5.8 and a substantial protein recovery rate of 97%.

Quantitative assessment of LPS-HBsAg interaction by introducing a novel application of immunoaffinity chromatography.

Lipopolysaccharide (LPS), as a stubborn contamination, should be monitored and kept in an acceptable level during the pharmaceutical production process. Recombinant hepatitis B surface antigen (r-HBsAg) is one of the recombinant biological products, which is probable to suffer from extrinsic endotoxin due to its long and complex production process. This research aims to assess the potential interaction between LPS and r-HBsAg by recruiting immunoaffinity chromatography (IAC) as a novel tool to quantify the interaction. Molecular modeling was performed on the HBsAg molecule to theoretically predict its potential binding and interaction sites. Then dynamic light scattering (DLS) analysis was implemented on HBsAg, LPS, and mixtures of them to reveal the interaction. The virus-like particle (VLP) structure of HBsAg and the ribbon-like structure of LPS were visualized by transmission electron microscopy (TEM). Finally, the interaction was quantified by applying various LPS/HBsAg ratios ranging from 1.67 to 120 EU/dose in the IAC. Consequently, the LPS/HBsAg ratios in the eluate were measured from 1.67 to a maximum of 92.5 EU/dose. The results indicated that 77 to 100% of total LPS interacted with HBsAg by an inverse relationship to the incubated LPS concentration. The findings implied that the introduced procedure is remarkably practical in the quantification of LPS interaction with a target recombinant protein.

A novel application of ion exchange chromatography in recombinant hepatitis B vaccine downstream processing: Improving recombinant HBsAg homogeneity by removing associated aggregates.

Production of recombinant HBsAg as a main component of the hepatitis B vaccine has already been established in commercial scale. So far, many studies have been performed to optimize the production process of this recombinant vaccine. However, still aggregation and dissociation of rHBsAg virus-like particles (VLPs) are major challenges in downstream processing of this biomedicine. The structural diversity of rHBsAg is dependent on many factors including cell types, molecular characteristics of the expressed recombinant rHBsAg, buffer composition as well as operation condition and specific characteristics of each downstream processing unit. Hence, it is not relatively easy to implement a single strategy to prevent aggregation formation in already established rHBsAg production processes. In this study, we examined the efficacy of weak anion exchange chromatography (IEC)- packed with DEAE Sepharose Fast Flow medium- on isolation of rHBsAg VLPs from aggregated structures. For this purpose, the influence of ionic strength of elution buffer as a key factor was investigated in isolation and recovery of rHBsAg VLPs. The elution buffer with electrical conductivity between 27 and 31 mS/cm showed the best results for removing aggregated rHBsAg based on SEC-HPLC analysis. The results showed that in the selected conductivity range, about 79% of rHBsAg was recovered with purity above 95%. The percentage of rHBsAg VLPs in the recovered sample was between 94% and 97.5% indicating that we could obtain highly homogeneous rHBsAg within the acceptable quality level. The TEM, SDS-PAGE and western blot analysis were also in agreement with our quantitative measurements.

Exploration of Recombinant Streptokinase Degradation Products Under Various pH Reduction Conditions in Downstream Processing.

BACKGROUND: Methods of producing streptokinase, which can be used in the treatment of myocardial infarction, by hemolytic streptococci and recombinant E. coli have been described in patents since 1955. Degradation products in active pharmaceutical ingredients (APIs) and finished pharmaceutical products are considered as impurities and it is required that these degradation impurities are minimized or rather avoided throughout manufacturing process. OBJECTIVE: The aim of this study was to explore the occurrence of rSK degradation during acidification step in downstream processing. METHODS: The polyclonal antibody was produced by immunization of New Zealand white (NZW) rabbit with pure rSK (purity>98%). The solubilized inclusion bodies with various pH values (4.2, 5.0 and 6.0) were analyzed by Western blotting using rSK polyclonal antibody. RESULTS: Western blot analysis demonstrated the generation of rSK degradation products (with the molecular weight of about 27, 20 and 17 kDa) when the pH value of the solubilized inclusion bodies was reduced to 5.0 and 4.2, while no degradation of rSK observed at pH 6.0. CONCLUSION: This study demonstrates that the level of pH reduction in the solubilized inclusion bodies during downstream processing plays an important role in generating rSK degradation products, and substantial post-solubilization degradation of rSK occurs at pH lower than 6.0. Development of these degradation impurities, which cannot be eliminated by subsequent chromatographic purifications, can be exclusively avoided during acidification procedure by appropriate pH adjustment approach in downstream processing.

Effect of post-solubilization conditions on the yield and efficiency of recombinant streptokinase purification at large-scale.

Streptokinase, a plasminogen activator which converts plasminogen to plasmin and consequently promotes fibrinolysis, is the leading drug for treating acute myocardial infarction in developing countries and its production is industrially demanded. In this work, the substantial influence of inclusion body (IB) post-solubilization condition on the performance of a sequential chromatography method for large-scale purification of recombinant streptokinase was demonstrated. In the preliminary experiments, various post-solubilization pH conditions were studied, and it was shown that the pH value of solubilized inclusion bodies (i.e., in 4M urea) had a marked impact on the purity of streptokinase obtained at the end of post-solubilization process. When the pH value of the solution containing solubilized IBs was decreased from 7.5 to 6.5 and 6.0, the greatest increases (10% and 27%, respectively) in streptokinase purity occurred. The influence of different post-solubilization pH conditions on the efficiency and yield of large-scale chromatographic purification methods was next investigated. When the solubilized IBs solution with pH adjusted to 6.0 was utilized for subsequent sequential chromatography process, the complete elution peak with high overall yield (91.3%) and purity (98%) was achieved. In comparison to this, while the sequential chromatography procedure was instigated by using the solubilized IBs solution with pH 4.2, four elution fractions (EF1 to EF4) with disparate target protein purities (i.e., 57%, 77.3%, 91.4% and 86.7%, respectively) were attained, the process was incompletely effective, and the highest recovery and purity figures (81.8% and 91.4%, respectively, belonging to EF3) were much lower than those for the earlier process.