Isolation of immunoglobulins from cheese whey using ultrafiltration and immobilized metal affinity chromatography

Shelf life and storage stability of spray-dried bovine colostrum powders under different storage conditions

Spray dried bovine colostrum (SDBC) powders were packaged in aluminium-laminated polyethylene (ALPE) and polyethylene terephthalate (PET) pouches and then stored under different conditions (25 °C and 50 % relative humidity (RH), 4 °C and 40-70 % RH, 50 °C and 20-50 % RH). The shelf life of SDBC powder was evaluated as 425.5 and 86.5 days in ALPE and PET pouches under 25 °C and 50 % RH, respectively. The storage stability of SDBC powder in terms of quality parameters including thiobarbituric acid (TBA), hydroxymethyl furfural (HMF), colour change, moisture content and IgG concentration was studied in both packaging materials under different storage conditions. Results showed that ALPE pouches were more suitable for packaging SDBC powder than PET pouches and storage condition of 4 °C and 40-70 % RH was relative suitable for keeping quality of SDBC powder. The glass transition concept was helpful for evaluating the chemical stability of SDBC powder during storage.

Purification of egg yolk immunoglobulin (IgY) by ultrafiltration: effect of pH, ionic strength, and membrane properties

Immunoglobulin Y (IgY) was purified from hen egg yolk water-soluble protein fraction by ultrafiltration-diafiltration with different membranes. The effect of changing solution properties (pH and ionic strength) on purification factor (P), process selectivity (Psi), and IgY recovery (RIgY) was studied. Salt presence (150 and 1500 mM) decreased the selectivity and purity factor. This effect was more evident at pH values closer to or higher than the IgY's isoelectric point. The best results were obtained in the absence of salt at pH values of 5.7 and 6.7 using poliethersulfone (PES) and modified PES (MPES), respectively. Process selectivity was doubled, and IgY's purification factors were increased in more than 1 order of magnitude when diafiltration was used. Results from this work show the potential of membrane technology for the purification of IgY from hen's egg yolk.

Bovine milk immunoglobulins against microbial human diseases

Immunoglobulins (Igs), also called antibodies, are present in milk and colostrum of all lactating species. Igs are divided into classes having different physico-chemical structures and biological activities. The major Ig classes in bovine and human milk are IgA, IgG and IgM. Bovine colostral Igs provide the newborn calf with passive immune protection against microbial infections until the calf’s own immune system matures. Colostral Ig preparations designed for farm animals have been commercially available for many years. Potential health benefits attributed to bovine colostrum have increased manufacture and marketing of colostral Ig-based dietary supplements also for human use. Furthermore, specific anti-microbial antibodies can be produced into colostrum by immunizing cows with vaccines made of pathogenic microorganisms. These antibodies can be concentrated and used to formulate so-called immune milk preparations. Such preparations have proven effective in prevention of animal and human infections caused, e.g. by rotavirus, Shigella flexneri, Escherichia coli, Clostridium difficile, Streptococcus mutans, Cryptosporidium parvum and Helicobacter pylori. Their therapeutic efficacy, however, seems limited. A few immune milk products have been commercialized and more can be expected in the future for use, e.g. as a supportive means in antibiotic treatments and for prevention of hospital infections.

Milk immunoglobulins for health promotion

The biological function of bovine colostral immunoglobulins is to provide the newborn calf with adequate passive immune protection against microbial infections. Immunoglobulin preparations designed for farm animals are commercially available, and some colostrum-based products are marketed also for humans as dietary supplements. The concentration of specific antibodies against a certain pathogenic microorganism can be raised in colostrum and milk by immunizing cows with this pathogen or its antigen. Advances in bioseparation and chromatographic techniques have made it possible to fractionate and enrich these antibodies and formulate so-called hyperimmune colostral or milk preparations. Their efficacy in prevention and treatment of various microbial infections has been evaluated in numerous studies. Immune milk preparations have proven effective in prophylaxis against infections caused by a variety of gastrointestinal pathogens. Their therapeutic efficacy, however, seems more limited. A few commercial immune milk products are already on market and more applications can be expected in the coming years. This article reviews the recent progress made in isolation techniques of bovine immunoglobulins and the application of colostral and immune milk preparations in fighting various microbial infectious diseases in humans.

Demonstration of a strategy for product purification by high-gradient magnetic fishing: recovery of superoxide dismutase from unconditioned whey

A systematic approach for the design of a bioproduct recovery process employing magnetic supports and the technique of high-gradient magnetic fishing (HGMF) is described. The approach is illustrated for the separation of superoxide dismutase (SOD), an antioxidant protein present in low concentrations (ca. 0.15-0.6 mg L(-1)) in whey. The first part of the process design consisted of ligand screening in which metal chelate supports charged with copper(II) ions were found to be the most suitable. The second stage involved systematic and sequential optimization of conditions for the following steps: product adsorption, support washing, and product elution. Next, the capacity of a novel high-gradient magnetic separator (designed for biotechnological applications) for trapping and holding magnetic supports was determined. Finally, all of the above elements were assembled to deliver a HGMF process for the isolation of SOD from crude sweet whey, which consisted of (i) binding SOD using Cu2+ -charged magnetic metal chelator particles in a batch reactor with whey; (ii) recovery of the "SOD-loaded" supports by high-gradient magnetic separation (HGMS); (iii) washing out loosely bound and entrained proteins and solids; (iv) elution of the target protein; and (v) recovery of the eluted supports from the HGMF rig. Efficient recovery of SOD was demonstrated at approximately 50-fold increased scale (cf magnetic rack studies) in three separate HGMF experiments, and in the best of these (run 3) an SOD yield of >85% and purification factor of approximately 21 were obtained.

Isolation and partial characterization of catalytic antibodies with oligonuclease activity from bovine colostrum

Catalytic antibodies (abzymes) which hydrolyze RNA and DNA were isolated from bovine colostrum by sequential chromatography on Protein A Sepharose, denaturated DNA-cellulose, Mono Q, and gel permeation chromatography on Superose 12 at pH 2.3 after acidic shock. Metachromatic agar containing toluidine blue and yeast RNA was used to measure RNase activity. Electrophoresis in agarose showed DNase activity on plasmid DNA from Escherichia coli and DNA from calf thymus in fractions from all 4 purification steps. Gel permeation chromatography showed that the abzymes hydrolysed both a single-stranded polyadenylic acid (Poly A) and single-stranded polycitidylic acid (Poly C), while partially purified RNase from the colostrum hydrolysed Poly (C), but not Poly (A). Electrophoresis of purified abzymes under denaturing conditions showed protein bands of molecular mass corresponding to heavy and light chains of IgG. The abzymes immunoreacted with anti-bovine IgG. The RNase activity of the purified abzymes represented 0.022% of total RNase activity in the colostrum; acid shock and gel filtration at low pH reduced the specific RNase activity of abzymes 3.6-fold. The RNase activity of abzymes at pH 6.6 was reduced by 90% by heat treatment at 75 degrees C for 52 min.

Milk immunoglobulins and complement factors

The importance of colostrum for the growth and health of newborn offspring is well known. In bovine colostrum, the antibody (immunoglobulin) complement system provides a major antimicrobial effect against a wide range of microbes and confers passive immunity until the calf's own immune system has matured. Bovine serum and lacteal secretions contain three major classes of immunoglobulins: IgG, IgM and IgA. The immunoglobulins are selectively transported from the serum into the mammary gland, as a result of which the first colostrum contains very high concentrations of immunoglobulins (40-200 mg/ml). IgG1 accounts for over 75 % of the immunoglobulins in colostral whey, followed by IgM, IgA and IgG2. All these immunoglobulins decrease within a few days to a total immunoglobulin concentration of 0.7-1.0 mg/ml, with IgG1 representing the major Ig class in milk throughout the lactation period. Together with the antibodies absorbed from colostrum after birth, the complement system plays a crucial role in the passive immunisation of the newborn calf. The occurrence of haemolytic or bactericidal complement activity in bovine colostrum and milk has been demonstrated in several studies. This review deals with the characteristics of bovine Igs and the complement system to be exploited as potential ingredients for health-promoting functional foods.

Efficiency and protective effect of encapsulation of milk immunoglobulin G in multiple emulsion

Milk immunoglobulin G (IgG), separated with protein G affinity chromatography, and IgG in colostral whey were encapsulated by 0.5% (w/v) of Tween 80, sucrose stearate, or soy protein, which were used as secondary emulsifiers in the water in oil in water type multiple emulsion. The residual contents of separated IgG and IgG in colostral whey, ranging from 58.7 to 49.7% and from 13.2 to 21.3%, respectively, in the inner water phase (water phase surrounded by oil phase) with emulsifiers were determined by ELISA. However, the emulsion stability decreased after 24 h, and the residual IgG content in the inner water phase was lowered. Encapsulation of IgG in the multiple emulsion increased the stability of separated IgG against acid (pH 2.0) and alkali (pH 12.0) by 21-56% and 33-62%, respectively, depending on the emulsifier used. Moreover, multiple emulsion also provided a remarkable protective effect on separated IgG stability against proteases. The residual contents of separated IgG in multiple emulsion, using Tween 80 as secondary emulsifier, incubated for 2 h with pepsin (pH 2.0) and trypsin and chymotrypsin (pH 7.6) (enzyme/substrate = 1/20) were 35.4, 72.5, and 82.3%, whereas those of separated IgG in enzyme solution were only 7.2, 33. 1, and 35.2%, respectively. However, the separated IgG loss during the preparation of multiple emulsion was almost 41-50%.

Purification of monospecific polyclonal antibodies from hyperimmune bovine whey using immunoaffinity chromatography

Whey, a by-product of cheese production, is a potential source of proteins. Immunization of dairy cows in mid-lactation with mouse IgG and dinitrophenyl-keyhole limpet hemocyanin resulted in the formation of antibodies to these antigens in both blood serum and milk. The antibodies remained in whey during cheese making, and were isolated by immunoaffinity chromatography on matrices with immobilized antigens. The isolated monospecific antibodies were pure and retained their reactivity to antigens.