Purification of equine IgG using membrane based enhanced hybrid bioseparation technique: A potential method for manufacturing hyperimmune antibody

Membrane-Based Hybrid Method for Purifying PEGylated Proteins

PEGylated proteins are usually purified using chromatographic methods, which are limited in terms of both speed and scalability. In this paper, we describe a microfiltration membrane-based hybrid method for purifying PEGylated proteins. Polyethylene glycol (or PEG) is a lower critical solution temperature polymer which undergoes phase transition in the presence of a lyotropic salt and forms micelle-like structures which are several microns in size. In the proposed hybrid method, the PEGylated proteins are first converted to their micellar form by the addition of a lyotropic salt (1.65 M ammonium sulfate). While the micelles are retained using a microfiltration membrane, soluble impurities such as the unmodified protein are washed out through the membrane. The PEGylated proteins thus retained by the membrane are recovered by solubilizing them by removing the lyotropic salt. Further, by precisely controlling the salt removal, the different PEGylated forms of the protein, i.e., mono-PEGylated and di-PEGylated forms, are fractionated from each other. Hybrid separation using two different types of microfiltration membrane devices, i.e., a stirred cell and a tangential flow filtration device, are examined in this paper. The membrane-based hybrid method for purifying PEGylated proteins is both fast and scalable.

Simple and efficient protocol for immunoglobulin Y purification from chicken egg yolk

Besides being a common food component broadly consumed worldwide, egg yolk immunoglobulin Y (IgY) has essential therapeutic potentials. In fact, in a time of ever-increasing risk of antibiotic resistance, it is crucial to find new ways to battle infection, and oral administration of preformed specific antibodies represents one of the most attractive approaches against infection. Infectious diseases of bacterial and viral origin in humans and animals can be controlled and passively cured by orally applied IgYs isolated from chicken egg yolks. Despite multiple obvious advantages of oral administration of IgY, harvesting IgY from egg yolk in a pure form is a challenging task.

In this study, we developed a fast, simple, cost-effective, and efficient protocol for IgY isolation from chicken egg yolks. First, egg yolk was collected and diluted with 5 volumes of cold distilled water, homogenized, pH adjusted, and centrifuged. Next, the supernatant was collected, to which caprylic acid at concentration of 2% v/v was added, followed by pH adjustment to pH 5.0, centrifugation at 4°C, and collection of the resulting supernatant. This step was repeated twice, with adding 2% v/v of caprylic acid each time. The final supernatant was concentrated using ultrafiltration, and the IgY purity and activities were checked by SDS-PAGE, western blotting, and ELISA. The sequential (2, 2, 2%) addition of caprylic acid yielded IgY with a purity of 63.5, 90.6, and 95.8%, respectively, and reached 97.9% after ultrafiltration at pH 9.0. The IgY activity increased exponentially to reach 99% after the ultrafiltration step.

The proposed caprylic-acid-based protocol of IgY purification from the yolk of chicken eggs seems to be simple, fast, direct, and very cheap. This indicates that this protocol has great potential for scale-up processing.

Purification of IgG against ribonucleoprotein by a homemade immunoaffinity chromatography column for rabies diagnosis

Polyclonal or monoclonal antibodies against rabies virus ribonucleoprotein (RNP) conjugated to fluorescein isothiocyanate (FITC) have been employed for Rabies virus (RABV) antigen detection by the direct fluorescent antibody test (DFA). To date, these biomolecules have been purified by traditional methods such as precipitation by ammonium sulfate or ion exchange chromatography followed by ammonium sulfate precipitation, which allows only for partial detection of the protein of interest. In this study, we aimed to purify anti-RNP polyclonal horse IgG antibodies by cation-exchange chromatography in combination with a homemade immunoaffinity chromatography on RNP immobilized (RNP-IAC). Furthermore, to evaluate the accuracy of the prepared anti-RNP IgG fluorescent antibody in diagnostic purposes, DFA was applied for RABV antigen detection in suspected brain samples of different animal species. The combination of these two techniques made it possible to obtain antibodies with high selectivity and purity. Compared with the performance of the traditional method, anti-RNP IgG antibodies purified by RNP-IAC can be obtained from a smaller volume of hyperimmune serum and with greater avidity. Furthermore, the results obtained by DFA analyses revealed that the prepared anti-RNP IgG fluorescent antibody achieved 100% diagnostic specificity and sensitivity for RABV antigen detection. Thus, two-technique chromatographic, including RNP-IAC technology could be appropriate methods for the purification of polyclonal anti-RNP IgG for the use as a diagnostic reagent for rabies.

Directing membrane chromatography to manufacture α1-antitrypsin from human plasma fraction IV

The surging demand for plasma proteins, mainly driven by the growing market and the development of new therapeutic indications, is promoting manufacturers to improve the throughput of plasma proteins. Due to the inherent convective mass transfer, membrane chromatography has been proved to be an efficient approach for extracting a small amount of target proteins from large-volume feed. In this study, α1-antitrypsin (AAT) was extracted from human plasma fraction IV by a two-step membrane chromatography. An anion-exchange membrane chromatography (AEMC) was used to capture the plasma proteins in bind/elute mode, and the obtained effluent was further polished by a hydrophobic interaction membrane chromatography (HIMC) in flow-through mode. Under optimal conditions, the recovery and purity of AAT achieved 87.0% and 0.58 AAT/protein (g/g) by AEMC, respectively. After the precise polishing by HIMC, the purity of AAT was 1.22 AAT/protein (g/g). The comparison results showed that membrane chromatography outperformed column chromatography in both steps because of its high throughput. This two-step membrane chromatography could obtain an AAT recovery of 83.3% and an activity recovery of 91.4%. The outcome of this work not only offers an alternative process for protein purification from plasma, but also provides guidelines for manufacturing product from a large-volume feed with multi-components by membrane chromatography.