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

IgY technology: Methods for developing and evaluating avian immunoglobulins for the in vitro detection of biomolecules

The term “IgY technology” was introduced in the literature in the mid 1990s to describe a procedure involving immunization of avian species, mainly laying hens and consequent isolation of the polyclonal IgYs from the “immune” egg yolk (thus avoiding bleeding and animal stress). IgYs have been applied to various fields of medicine and biotechnology. The present article will deal with specific aspects of IgY technology, focusing on the currently reported methods for developing, isolating, evaluating and storing polyclonal IgYs. Other topics such as current information on isolation protocols or evaluation of IgYs from different avian species are also discussed. Specific advantages of IgY technology (e.g., novel antibody specificities that may emerge via the avian immune system) will also be discussed. Recent in vitro applications of polyclonal egg yolk-derived IgYs to the field of disease diagnosis in human and veterinary medicine through in vitro immunodetection of target biomolecules will be presented. Moreover, ethical aspects associated with animal well-being as well as new promising approaches that are relevant to the original IgY technology (e.g., development of monoclonal IgYs and IgY-like antibodies through the phage display technique or in transgenic chickens) and future prospects in the area will also be mentioned.

In vitro Inhibitory Activity of IgY Antibodies Against Salmonella Ser. Newport Isolated from Horses

Equine salmonellosis is caused by several Salmonella serotypes, including Salmonella Newport, which cause enterocolitis and diarrhea. Treatment usually includes the administration of antibiotics. However, since multidrug-resistant Salmonella is commonly detected, alternative options to control the pathogen are needed. One of these options is the use of specific egg yolk antibodies (IgY) for passive immunotherapy. Thus, the aim of our work was to produce IgY antibodies against an equine S. Newport strain and assess their in vitro inhibitory activity. To this end, laying hens were immunized with an inactivated S. Newport strain by using either Freund's or Montanide adjuvant and egg yolk extracts were obtained. The levels of specific IgY antibodies against Salmonella in sera and egg extracts were determined by dot-blot and microagglutination. Besides, the IgY extracts were characterized by total protein analysis, SDS-PAGE, Western Blot, and inhibition of bacterial motility. IgY extracts showed high purity (87.7 to 91.8 %), high microagglutination titers, and the ability to inhibit the motility of the bacterium. The results using Montanide were similar to those using the traditional Freund's adjuvant. Thus, Montanide may also be a good adjuvant to produce IgY. IgY-technology represents a potential tool for the control of salmonellosis in horses.

In vivo neutralization of bee venom lethality by IgY antibodies

Bee venom is a complex mixture of molecules, among which melittin and phospholipase A₂ (PLA₂) are the toxic components involved in envenoming accidents with multiple honeybee stings. Traditionally, the treatment of envenomings has been based on the administration of specific antibodies to neutralize the deleterious effects of toxins. An alternative to mammalian polyclonal antibodies is the use of egg yolk immunoglobulins (IgY) due to their advantages regarding animal welfare and lower costs of production as compared to the conventional production methods. In this work, a novel composition containing specific IgY antibodies was developed. After four immunizations, IgY extracted from the egg yolks was able to recognize several components of the bee venom, including melittin and PLA₂. The performance of IgY to neutralize the lethal activity was evaluated in a mouse model by using one median lethal dose (LD₅₀) of the bee venom. The effective dose of the IgY extract was determined as 30.66 μg/mg. These results demonstrate the feasibility to produce IgY-based antivenoms to treat envenomings by multiple bee stings.

Anticancer and immunomodulatory activity of egg proteins and peptides: a review

Eggs are widely recognized as a highly nutritious food source that offer specific health benefits for humans. Eggs contain all of the proteins, lipids, vitamins, minerals, and growth factors necessary for embryonic development. In particular, egg white and yolk proteins are considered functional food substances because they possess biological activities such as antimicrobial, antioxidant, metal-chelating, antihypertensive, anticancer, and immunomodulatory activities. Peptides produced via processes such as enzymatic hydrolysis, fermentation by microorganisms, and some chemical and physical treatments of egg proteins have been shown to enhance the functional properties and solubility of these peptides. Peptide activity is strongly related to amino acid sequence, composition, and length. At present, cancer remains among the leading causes of mortality worldwide, and therefore research aimed at developing new treatments for cancer immunotherapy is of great interest. The present review focuses primarily on the anticancer and immunomodulatory activities of egg proteins and their peptides and provides some insight into their underlying mechanisms of action. A number of egg proteins and peptides have been reported to induce apoptosis in cancer cells, protect against DNA damage, decrease the invasion ability of cancer cells, and exhibit cytotoxic and antimutagenic activity in various cancer cell lines. Furthermore, egg proteins and peptides can stimulate or suppress pro- or anti-inflammatory cytokines, as well as affect the production of inflammatory mediators in a variety of cell lines. In addition, the composition of eggs and the processes of egg proteins and peptides production will be discussed.

How Can the Value and Use of Egg Yolk Be Increased?

The major driving force for the egg consumption in the United States over the past few decades was processed egg. However, the consumption of egg through the processed egg reached the plateau in recent years because of the imbalance in the demands between the egg white and yolk products. The consumer demands for egg white products are very high while those for the egg yolk, the co-product of dried egg white, are low because of the negative perceptions on egg yolk. Two key approaches that can be used to increase the value and use of egg yolk are: (1) developing new commodity products by fractionating egg yolk and apply them in various food processing, and (2) separating functional proteins and lipids from yolk and use them as is or further develop functional peptides and functional lipids and use them as pharmaceutical, nutraceutical, and cosmeceutical agents. These approaches can diversify the use of egg yolk, which eventually will help increase the consumption of egg. This review (1) discusses the current use of egg yolk products and the development of new functional commodity products from egg yolk, (2) review the important functional components in egg yolk and overview the current separation methods and their applications, (3) discuss the production of functional peptides and lipids using the separated egg proteins and lipids, and (4) suggest the future directions for the best use of egg yolk components. Development of scale-up production methods, which is vital for the practical applications, is discussed when appropriate.

Novel biocompatible and self-buffering ionic liquids for biopharmaceutical applications

Antibodies obtained from egg yolk of immunized hens, immunoglobulin Y (IgY), are an alternative to the most focused mammal antibodies, because they can be obtained in higher titers by less invasive approaches. However, the production cost of high-quality IgY for large-scale applications remains higher than that of other drug therapies due to the lack of efficient purification methods. The search for new purification platforms is thus vital. The solution could be liquid-liquid extraction by using aqueous biphasic systems (ABS). Herein, we report the extraction and attempted purification of IgY from chicken egg yolk by using a new ABS composed of polymers and Good's buffer ionic liquids (GB-ILs). New self-buffering and biocompatible ILs based on the cholinium cation and anions derived from Good's buffers were synthesized and the self-buffering characteristics and toxicity were characterized. Moreover, when these GB-ILs are combined with PPG 400 (poly(propylene) glycol with a molecular weight of 400 g mol(-1)) to form ABS, extraction efficiencies, of the water-soluble fraction of proteins, ranging between 79 and 94% were achieved in a single step. Based on computational investigations, we also demonstrate that the preferential partitioning of IgY for the GB-IL-rich phase is dominated by hydrogen-bonding and van der Waals interactions.

Sequential separation of immunoglobulin Y and phosvitin from chicken egg yolk without using organic solvents

A study was conducted to develop a simple sequential separation protocol to separate phosvitin and IgY from egg yolk without using organic solvents. Egg yolk was diluted with 2 volumes of distilled water (DW), homogenized, and centrifuged. The precipitant was collected and homogenized with 4 volumes of 10% NaCl (wt/vol) in 0.05 N NaOH solution to extract phosvitin. The pH of the homogenate was adjusted to 4.0 and the precipitate was removed by centrifugation. The supernatant was collected and then heat-treated at 70°C for 30 min and centrifuged to remove impurities. The supernatant containing phosvitin was collected, had salts removed, and was concentrated and then freeze-dried. The supernatant from the centrifugation of diluted egg yolk was diluted again with 3 volumes of DW, and the precipitate was removed by centrifugation. The resulting supernatant was concentrated using ultrafiltration and then IgY was precipitated using 20% saturated (NH₄)₂SO₄+ 15% NaCl (wt/vol). The precipitant was collected after centrifugation at 3,400 × g for 30 min at 4°C and dissolved with DW, had salts removed, and then was freeze-dried. The purity of separated phosvitin and IgY was checked using SDS-PAGE and the proteins were verified using Western blotting. The purity of phosvitin and IgY was 97.2 and 98.7%, and the yield was 98.7 and 80.9%, respectively. The ELISA results indicated that the activities of separated IgY and phosvitin were 96.3 and 98.3%, respectively. This study proved that both phosvitin and IgY can be separated in sequence from egg yolk without using an organic solvent. Also, the method is very simple and has a high potential for scale-up processing.

Coral snake antivenom produced in chickens (Gallus domesticus)

The production of anti-snake venom from large mammal's blood has been found to be low-yielding and arduous, consequently, antivenom immunoglobulins for treatment are achieved regularly as polyvalent serum. We have standardized an undemanding technique for making purified immunoglobulin IgY antivenom consisting of polyclonal antibodies against coral snake venom in the egg yolk of immunized hens. We have adapted a reported process of antibody purification from egg yolks, and achieved 90% antibody purity. The customized technique consisted of the removal of lipids from distilled water-diluted egg yolks by a freeze–thaw sequence. The specific immunoglobulins were present in the egg yolk for up to 180 days postimmunization. Therefore, by means of small venom quantities, a significant amount of immunoglobulins were found in an adequately purified state (The obtained material contained about 90% pure IgY). The antigen binding of the immunoglobulins was detected by a double immunodiffusion test. Titers of antibodies in the yolk were estimated with a serum protection assay (Median effective dose = ED₅₀) (ED₅₀= 477 mg/kg). Given that breeding hens is economically feasible, egg gathering is noninvasive and the purification of IgY antibodies is quick and easy, chicken immunization is an excellent alternative for the production of polyclonal antibodies. To the best of our knowledge, this is the first coral snake antivenom prepared in birds.

Highly hydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes via postfabrication grafting of surface-tailored silica nanoparticles

Polyvinylidene fluoride (PVDF) has drawn much attention as a predominant ultrafiltration (UF) membrane material due to its outstanding mechanical and physicochemical properties. However, current applications suffer from the low fouling resistance of the PVDF membrane due to the intrinsic hydrophobic property of the membrane. The present study demonstrates a novel approach for the fabrication of a highly hydrophilic PVDF UF membrane via postfabrication tethering of superhydrophilic silica nanoparticles (NPs) to the membrane surface. The pristine PVDF membrane was grafted with poly(methacrylic acid) (PMAA) by plasma induced graft copolymerization, providing sufficient carboxyl groups as anchor sites for the binding of silica NPs, which were surface-tailored with amine-terminated cationic ligands. The NP binding was achieved through a remarkably simple and effective dip-coating technique in the presence or absence of the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) cross-linking process. The properties of the membrane prepared from the modification without EDC/NHS cross-linking were comparable to those for the membrane prepared with the EDC/NHS cross-linking. Both modifications almost doubled the surface energy of the functionalized membranes, which significantly improved the wettability of the membrane and converted the membrane surface from hydrophobic to highly hydrophilic. The irreversibly bound layer of superhydrophilic silica NPs endowed the membranes with strong antifouling performance as demonstrated by three sequential fouling filtration runs using bovine serum albumin (BSA) as a model organic foulant. The results suggest promising applications of the postfabrication surface modification technique in various membrane separation areas.

Chicken egg yolk antibodies (IgY) for detecting circulating antigens of Schistosoma japonicum

BACKGROUND

IgY isolated from egg yolk has been widely used in immunodiagnostic tests, including tests to detect circulating antigen (soluble egg antigen or SEA) of Schistosoma japonicum.

RESULTS

A sandwich ELISA was established using a combination of anti-S. japonicum SEA-IgY polyclonal antibodies and IgM monoclonal antibodies. To explore sensitivity and specificity of the sandwich ELISA, serum samples from 43 patients infected with S. japonicum were tested. All acute cases and 91.3% of the chronic cases showed a positive reaction. Only 5% of the control sera from healthy persons gave a positive response. Cross-reactions with antibodies to nine other parasites were rare.

CONCLUSION

The developed immunoassay is reasonably sensitive and specific. It could be used for field research and treatment efficacy assessments.