Chicken egg yolk antibodies as therapeutics in enteric infectious disease: a review

A dominant antigenic epitope on SARS-CoV spike protein identified by an avian single-chain variable fragment (scFv)-expressing phage

Severe acute respiratory syndrome (SARS) is a newly emergent human disease, which requires rapid diagnosis and effective therapy. Among antibody sources, immunoglobulin Y (IgY) is the major antibody found in chicken eggs and can be used as an alternative to mammalian antibodies normally used in research and immunotherapy. In this study, phage-expressing chicken monoclonal scFv antibody was chosen and characterized with phage display antibody technology. Truncated fragments of SARS-CoV spike protein were cloned in pET-21 vector and expressed in BL-21 Escherichia coli (E. coli) cells. After purification, the purity of these recombinant spike proteins was examined on SDS-PAGE and their identity verified with Western blot analysis using anti-his antibodies and sera from convalescent stage SARS-CoV-infected patients. Using these bacteria-derived proteins to immunize chickens, it was found that polyclonal IgY antibodies in the egg yolk and sera were highly reactive to the immunogens, as shown by Western blot and immunocytochemical staining analysis. A phage displaying scFv library was also established from spleen B cells of immunized chicken with 5 x 10(7) clones. After four panning cycles, the eluted phage titer showed a 10-fold increase. In sequence analysis with chicken germline gene, five phage clones reacted, with large dissimilarities of between 31 and 62%, in the complementarity-determining regions, one dominant phage 4S1 had strong binding to fragment Se-e, located between amino acid residues 456-650 of the spike protein and this particular phage had significantly strong binding to SARS-CoV-infected Vero E6 cells. Based on the results, we conclude that generating specific scFv-expressing phage binders with the phage display system can be successfully achieved and that this knowledge can be applied in clinical or academic research.

Egg yolk-derived immunoglobulin (IgY) against Porphyromonas gingivalis 40-kDa outer membrane protein inhibits coaggregation activity

The anaerobic bacterium Porphyromonas gingivalis, a major pathogen in periodontitis, aggregates with a number of oral bacteria to form dental plaque, which is important for its colonization. We previously cloned the gene coding the 40-kDa outer membrane protein (OMP) of P. gingivalis 381 and produced large amounts of the recombinant (r) protein. Affinity-purified rabbit antiserum against r40-kDa OMP effectively inhibited the coaggregation activity of P. gingivalis to oral bacteria, thus 40-kDa OMP was thought to be an important coaggregation factor of P. gingivalis. Further, since it is conserved among many P. gingivalis strains, this coaggregation factor may be an effective target for passive immunotherapy against P. gingivalis infection. Recently, passive immunization approaches using a specific antibody produced from hen egg yolk (IgY) have been developed for oral infectious diseases, and shown to be convenient and economic. In the present study, we immunized hens intramuscularly with r40-kDa OMP and obtained highly purified IgY from the egg yolks. The purified IgY specifically recognized r40-kDa OMP and also reacted with a functional coaggregation-associated domain peptide of 40-kDa OMP. Our results demonstrated that a ratio of purified IgY as low as 2.5 microg/150 microl significantly inhibited the coaggregation of P. gingivalis with Streptococcus gordonii, which was verified by a visual coaggregation assay and radioactivity-based quantitative micro-coaggregation assay. We concluded anti-r40-kDa OMP IgY may be useful for passive immunization against periodontal diseases caused by P. gingivalis infection.

Protection of Carassius auratus Gibelio against infection by Aeromonas hydrophila using specific immunoglobulins from hen egg yolk

Specific immunoglobulin (IgY) from egg yolk against Aeromonas hydrophila was produced by immunization of White Leghorn hens with formalin-killed whole cells of A. hydrophila. ELISA test using A. hydrophila as the coating antigen revealed that the specific antibody titer started to increase in the egg yolk at the 13th day post-immunization (P/N=2.18), reached the peak at the 56th day (P/N=13.82), and remained at high level until day 133 (P/N=7.03). The antibody was purified by saturated ammonium sulphate with a recovery rate of 63.5%. The specific IgY inhibited the growth of A. hydrophila at a concentration of 1.0 mg/ml during the 18 h incubation. Pre-treatment of polyploid gibel carps Carassius auratus Gibelio with specific IgY had a protection rate of 60% (6/10) against challenge with A. hydrophila, while none of the fishes in the control groups receiving sterile phosphate buffered saline (PBS) or non-specific IgY survived the challenge. Treatment of fishes with the specific IgY 4 h after the challenge also had lower mortality (70%, 7/10), a 30% reduction against the control PBS or non-specific IgY groups (10/10). These results indicate that specific IgY antibodies could be obtained easily from hens immunized with an inactivated A. hydrophila and could provide a novel alternative approach to control of diseases in fishes caused by this organism.

Formulation and delivery issues for monoclonal antibody therapeutics

Antibodies can have exquisite specificity of target recognition and thus generate highly selective outcomes following their systemic administration. While antibodies can have high specificity, the doses required to treat patients, particularly for a chronic condition, are typically large. Fortunately, advances in production and purification capacities have allowed for the exceptionally large amounts of highly purified monoclonal antibodies to be produced. Additionally, genetic engineering of antibodies has provided a stable of antibody-like proteins that can be easier to prepare. Together, these advances have made antibody-based therapies one of the most commonly pursued pharmaceuticals in biotechnology pipelines. With this success, however, has come a series of technical challenges in the formulation of antibody-based materials to maintain sufficient stability in a variety of configurations and sometimes at particularly high concentrations. This review focuses on issues related to identifying and verifying stable antibody-based formulations.

DNA-designed avian IgY antibodies: novel tools for research, diagnostics and therapy

We have recently demonstrated, using the duck Hepatitis B virus (DHBV) model, closely related to human HBV, that following DNA immunization of breeding ducks with a plasmid encoding the targeted protein, specific and biologically active IgY (egg yolk immunoglobulines) are vertically transmitted from their serum into the egg yolk from which they can be extracted and purified. Thus an egg can be considered as a small "factory" for antibody production, since about 60-100 mg of purified IgY can be obtained from each egg yolk of a DNA-immunized duck. One of the major advantages of this new method of "DNA-designed" IgY antibodies is their production via immunization with a gene vector that expresses a corresponding antibody in situ in the cells of an avian host. Therefore this approach allows direct generation of antibodies from plasmid DNA and avoids the costly and tedious preparation of purified antigens required for conventional antibody production. In addition, duck IgY are of remarkable high affinity, avidity and are highly neutralizing. Moreover, the epitope pattern of IgY generated by DNA immunization of ducks is closely related to that observed in viral infection. Such duck IgY are also of particular value as immunodiagnostic tools, since they do not cross-react serologically with mammalian immunoglobulins and complement. Because IgY are resistant to the gastric barrier, the recently described DNA-designed IgY specific to H. pylori Urease B can be of particular interest for passive immunotherapy of gastrointestinal tract infections. Another interesting application is the recent generation in our laboratory of DNA-designed IgY antibodies specific to HBsAg mutants. These antibodies are currently being used to design new diagnostic assay for detection of HBV mutants that are undetectable by actual tests. Moreover, this approach allowing a quick and inexpensive production of a new generation of antibodies will provide pertinent tools to link the fields of genomics and protcomics.

In vitro activity of IgY against recombinant VacA protein of Helicobacter pylori

AIM: To explore the physicochemical and biolo-gical properties of IgY extracted from the yolk of hen's egg immunized with recombinant VacA protein of Helicobacter pylori.

METHODS: The purified antigen of recombinant VacA was used to immunize the hens and the VacA-IgY antibody was extracted from the yolk of hen's egg by water dilution methods and then purified by deposition technique with ammonium sulfate. In order to evaluate VacA-IgY heat stability, the titer of VacA-IgY was detected by enzyme-linked immunosorbent assay (ELISA) after being heated for 15 min under different temperatures. VacA-IgY was added into Tris-HCl of different pH values and incubated under a temperature of 37℃ to access its acid stability using ELISA. The competence of anti-pepsin digestion was also measured by ELISA. The VacA⁺H. pylori were co-cultured with Hela cells and VacA-IgY antibody was added to observe its neutralization on the cytotoxity of H. pylori by MTT assay in vitro.

RESULTS: The activity of VacA-IgY was maintained about 50% after water baths (70℃, 15 min). The activity of VacA-IgY seldom changed at pH values 5.0-7.0, but declined rapidly below the pH value 5.0, even absolutely disappeared at pH value 2.0. After incubation with pepsin (pH4.0, 60 kU/L) for 1 h, the activity of VacA-IgY had no changes, and 2 h after incubation, it still maintained over 50%. The VacA-IgY antibody neutralized the cytotoxity of VacA⁺H. pylori in a concentration-dependent manner. VacA⁺H. pylori ultrasonic extracts inhibited 50% proliferation of Hela cells at a concentration of 20 mg/L, while VacA-IgY completely neutralized the cytotoxity of H. pylori at concentrations of 80-320 mg/L (P < 0.01).

CONCLUSION: The VacA-IgY antibody shows a good heat stability, certain acid stability, and competence of anti-pepsin digestion, and can neutralize the cytotoxity of VacA protein of H. pylori effectively in vitro.

Stable production of recombinant chicken antibody in CHO-K1 cell line

When compared with mammalian IgG, chicken IgY is advantageous in terms of cross-reactivity. In this study, two plasmids were constructed for expression of recombinant chicken IgY derived from a chicken hybridoma. The first was for expression of the light (L) chain, and the other was for the heavy (H) chain with a histidine (His) tag at the carboxy-terminal. After transfection of recombinant chicken IgY gene into Chinese hamster ovary cells, a transfectant designated HF33 that secreted the specific antibody was selected. HF33 cells produced recombinant IgY with His tag at 10-15 microg/10(6) cells/24 h. On Western blotting analysis, the recombinant IgY was detected as one band for the H chain and two bands for the L chain. The recombinant IgY was successfully purified in a one-step procedure using a nickel-affinity resin. These results indicate that the present recombinant chicken IgY is useful for further applications.

Chicken egg yolk antibodies (IgY-technology): a review of progress in production and use in research and human and veterinary medicine

The production of antibodies (Abs) in chickens and the extraction of specific Abs from egg yolk (IgY Abs) are increasingly attracting the interest of the scientific community, as demonstrated by the significant growth of the IgY literature. This review offers detailed and comprehensive information about IgY-technology, including: a) possibilities for hen keeping in accordance with the Three Rs principles; b) new insights into the IgY transfer mechanism from blood to yolk as a biological basis for the technology; c) the comparative characteristics of IgY Abs and IgG Abs; d) the high efficacy of the technique, in view of the extraordinary amount of IgY Ab produced by one hen in one year (between 20 g and 40 g IgY in total); e) comparisons between the efficacies of IgY Abs and IgG Abs (rabbit, sheep, mouse) in several immunological assays; f) immunisation protocols, as well as the most commonly used IgY-extraction procedures; g) new possibilities for application in human and veterinary medicine, including strategies for the treatment of Helicobacter pylori infection or fatal intestinal diseases in children, particularly in poor countries, for reducing the use of antibiotics, and, in Asia and South America, for producing Abs against snake, spider and scorpion venoms; and h) the use of IgY Abs in various fields of research, also taking into consideration recent developments in South America (particularly Argentina and Cuba) and in Asia.

Antibodies: an alternative for antibiotics?

In 1967, the success of vaccination programs, combined with the seemingly unstoppable triumph of antibiotics, prompted the US Surgeon General to declare that "it was time to close the books on infectious diseases." We now know that the prediction was overly optimistic and that the fight against infectious diseases is here to stay. During the last 20 yr, infectious diseases have indeed made a staggering comeback for a variety of reasons, including resistance against existing antibiotics. As a consequence, several alternatives to antibiotics are currently being considered or reconsidered. Passive immunization (i.e., the administration of more or less pathogen-specific antibodies to the patient) prior to or after exposure to the disease-causing agent is one of those alternative strategies that was almost entirely abandoned with the introduction of chemical antibiotics but that is now gaining interest again. This review will discuss the early successes and limitations of passive immunization, formerly referred to as "serum therapy," the current use of antibody administration for prophylaxis or treatment of infectious diseases in agriculture, and, finally, recent developments in the field of antibody engineering and "molecular farming" of antibodies in various expression systems. Especially the potential of producing therapeutic antibodies in crops that are routine dietary components of farm animals, such as corn and soy beans, seems to hold promise for future application in the fight against infectious diseases.

Effect of dietary anti-urease immunoglobulin Y on Helicobacter pylori infection in Mongolian gerbils

BACKGROUND AND AIM

Helicobacter pylori is known to be a major pathogenic factor in the development of gastritis, peptic ulcer disease and gastric cancer. Recently, chicken egg yolk immunoglobulin Y (IgY) has been recognized as an inexpensive antibody source for passive immunization against gastrointestinal infections. The present study was designed to investigate the effect of anti-urease IgY on H. pylori infection in Mongolian gerbils.

METHODS

H. pylori-infected Mongolian gerbils were administered a diet containing anti-urease IgY, with or without famotidine (F). After 10 weeks, bacterial culture and measurement of the gastric mucosal myeloperoxidase (MPO) activity were performed. In a second experiment, another group of gerbils was started on a diet containing F + IgY a week prior to H. pylori inoculation. After 9 weeks, these animals were examined.

RESULTS

In the H. pylori-infected gerbils, there were no significant differences in the level of H. pylori colonization among the different dietary and control groups. However, the MPO activity was significantly decreased in the H. pylori group administered the F + IgY diet compared with that in the H. pylori group administered the IgY, F, or control diet. Furthermore, in the gerbils administered the F + IgY diet prior to the bacterial inoculation, inhibition of H. pylori colonization and suppression of the elevated gastric mucosal MPO activity were observed.

CONCLUSIONS

Oral administration of urease-specific IgY not only inhibited H. pylori disease activity in H. pylori-infected gerbils, but also prevented H. pylori colonization in those not yet infected. These encouraging results may pave the way for a novel therapeutic and prophylactic approach in the management of H. pylori-associated gastroduodenal disease.

Refinement of Polyclonal Antibody Production by Combining Oral Immunization of Chickens with Harvest of Antibodies from the Egg Yolk

Polyclonal antibody production in mammals is generally associated with multiple injections of antigens and adjuvants and repeated blood sampling procedures. During the past 20 yr, the use of chickens instead of mammals for this purpose has increased. A major advantage of using birds is that the antibodies can be harvested from the egg yolk instead of serum, thus making blood sampling obsolete. In addition, the antibody productivity of an egg-laying hen is much greater than that of a similar sized mammal. This article focuses on the developments in oral immunization strategies for chickens that combined with the antibodies from the egg yolk, have great potential for active implementation of the three Rs (replacing, reducing, and refining the use of laboratory animals to the extent possible) in polyclonal antibody production schemes.

Affinity separation: divide and conquer the proteome

A major challenge in protein target discovery and validation is how to specifically dissect complex protein mixtures and measure trace targets. Immunoaffinity-based protein capture, separation and detection have proven to be one of the most effective approaches. Avian IgY antibody microbeads (Seppro™), representing a type of novel and specific protein sorbent, have several distinct advantages over IgG. Their utility and applications are compared with those of IgG and other affinity reagents.:

Effect of food protein supplements on Salmonella enteritidis infection and prevention in laying hens

Reduction of intestinal colonization of Salmonella enteritidis (SE) during the grow-out period is crucial to provide safer eggs, minimize economic losses, and reduce the spread of human salmonellosis. In the search for novel elimination and prevention methods based on feed supplementation, the effects of feed supplemented with nonimmunized egg yolk powder (did not contain anti-S. enteritidis antibodies), immunized egg yolk powder (with anti-S. enteritidis antibodies), egg yolk proteins, egg white, and skim milk powder were examined on laying hens. In the elimination study, the chickens were orally infected with SE then given a supplemented feed of 5, 10, or 15% (wt/wt) of each of the test samples. Fecal samples tested weekly showed an absence of SE after the first week of feeding nonimmunized egg yolk powder and a gradual decrease with the other samples. In the prevention study, Salmonella-free chickens were fed the supplemented feed for 4 wk and then infected orally. Fecal samples tested for 4 wk showed that SE was prevented from colonizing the intestinal tract throughout the test period by nonimmunized egg yolk powder, whereas the other samples only delayed the colonization. None of the fed supplements disrupted the balance of the intestinal microflora, and the counts in the feces remained constant. These results show that the administration of only 5.0% (wt/wt) of nonimmunized egg yolk powder can eliminate and prevent SE colonization in laying hens with no adverse effects. Furthermore, the present results indicate that hen egg yolk contains novel anti-adhesive or immunomodulatory components that may act to prevent SE infection.

Fine mapping of sequential neutralization epitopes on the subunit protein VP8 of human rotavirus

The epitopes of the HRV (human rotavirus), especially those involved in virus neutralization, have not been determined in their entirety, and would have significant implications for HRV vaccine development. In the present study, we report on the epitope mapping and identification of sequential neutralization epitopes, on the Wa strain HRV subunit protein VP8, using synthetic overlapping peptides. Polyclonal antibodies against recombinant Wa VP8 were produced previously in chicken, and purified from egg yolk, which showed neutralizing activity against HRV in vitro. Overlapping VP8 peptide fragments were synthesized and probed with the anti-VP8 antibodies, revealing five sequential epitopes on VP8. Further analysis suggested that three of the five epitopes detected, M1-L10, I55-D66 and L223-P234, were involved in virus neutralization, indicating that sequential epitopes may also be important for the HRV neutralization. The interactions of the antibodies with the five epitopes were characterized by an examination of the critical amino acids involved in antibody binding. Epitopes comprised primarily of hydrophobic amino acid residues, followed by polar and charged residues. The more critical amino acids appeared to be located near the centre of the epitopes, with proline, isoleucine, serine, glutamine and arginine playing an important role in the binding of antibody to the VP8 epitopes.

The use of gene-specific IgY antibodies for drug target discovery

Genomics and gene expression data require interpretation at the protein level to validate the biological or pathological findings. To match with the efficiency and capacity of DNA microarray application, methods and approaches of protein analysis in multiplex and high-throughput manner are required for effectively discovering disease-related proteins. Two-dimensional gel and MS-based technologies provide researchers with such approaches, but neither of them can directly and selectively detect target proteins in situ. Antibodies are one of the most crucial tools for meeting this need. Efficient generation of antibodies based on genomics and gene-expression information is an important strategy for producing gene-specific antibodies to link genome to proteome. Avian immunoglobulins isolated from egg yolk (so-called IgY) have several attractive advantages over conventional IgG antibodies.

Oral immunoglobulin for the prevention of rotavirus infection in low birth weight infants

BACKGROUND

Rotavirus infection is the most common neonatal nosocomial viral infection. Epidemics with the newer P(6)G9 strains have been reported in neonatal units worldwide. These strains can cause severe symptoms in infected infants. Infection control measures become necessary and the utilisation of hospital resources increase. Local mucosal immunity in the intestine to rotavirus is important in the resolution of infection and protection against subsequent infections. Boosting local immunity by oral administration of anti-rotaviral immunoglobulin preparations might be a useful strategy in preventing rotaviral infections, especially in low birth weight babies.

OBJECTIVES

To determine the effectiveness and safety of oral immunoglobulin preparations for the prevention of rotavirus infection in hospitalised low birthweight infants (birth weight less than 2500 gms)

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2002), MEDLINE, EMBASE and CINAHL were searched. Science Citation Index was searched for all articles which referenced Barnes 1982. The proceedings of the Pediatric Academic Societies which were published in the journal, Pediatric Research from 1991 onwards were searched as well as abstracts of doctoral dissertations and theses from 1960 onwards. The above mentioned search strategy was completed in June 2002. Authors prominent in the field were contacted for any unpublished articles and more information on published articles was sought. Reference lists of identified clinical trials and personal files were reviewed.

SELECTION CRITERIA

The criteria used to select studies for inclusion were: 1) DESIGN: randomised or quasi-randomised controlled trials. 2) PARTICIPANTS: Hospitalised low birthweight infants. 3) INTERVENTION: Oral immunoglobulin preparations for prevention of rotavirus infection compared to placebo OR no intervention. 4) At least one of the following outcomes were reported: All cause mortality during hospital stay, mortality due to rotavirus infection during hospital stay, rotavirus infection, duration of diarrhoea, need for rehydration, duration of viral excretion, duration of infection control measures, length of hospital stay in days, recurrent diarrhoea or chronic diarrhoea.

DATA COLLECTION AND ANALYSIS

The two reviewers independently abstracted data from the included trials

MAIN RESULTS

One published study (Barnes 1982) was eligible for inclusion in this review. Two additional studies are awaiting assessment re eligibility for inclusion. Barnes 1982 found no significant difference in the rates of rotavirus infection after oral gammaglobulin versus placebo in hospitalised low birthweight babies [RR 1.27 (95% CI 0.65-2.37)]. In the subset of infants who became infected with rotavirus after receiving gammaglobulin or placebo for prevention of rotavirus infection, there was no significant difference in the duration of rotavirus excretion between the group who had gammaglobulin (mean 2 days, range 1-4 days) and the group who had placebo (mean 3 days, range 1-6 days). No adverse effects were reported by Barnes 1982 after administration of oral immunoglobulin preparations.

REVIEWER'S CONCLUSIONS

Current evidence from one randomised controlled trial does not support the routine use of oral immunoglobulin preparations for the prevention of rotavirus infection in low birth-weight infants. However, newer immunoglobulin preparations which have been found to be effective in older children have not been tested in neonatal trials. Therefore, researchers should be encouraged to conduct well designed trials in neonates at risk for rotavirus infections using the newer preparations of anti-rotaviral immunoglobulins (colostrum, egg yolk immunoglobulins). Such trials should also include cost effectiveness evaluations.

Oral immunoglobulin for the treatment of rotavirus infection in low birth weight infants

BACKGROUND

Rotavirus infection is the most common neonatal nosocomial viral infection. Epidemics with the newer P(6)G9 strains have been reported in neonatal units worldwide. These strains can cause severe symptoms in most infected infants. Infection control measures become necessary and the utilisation of hospital resources increase. Local mucosal immunity in the intestine to rotavirus is important in the resolution of infection and protection against subsequent infections. Boosting local immunity by oral administration of anti-rotaviral immunoglobulin preparations might be a useful strategy in treating rotaviral infections, especially in low birth weight babies.

OBJECTIVES

To determine the effectiveness and safety of oral immunoglobulin preparations for the treatment of rotavirus infection in hospitalised low birthweight infants (birth weight less than 2500 gms)

SEARCH STRATEGY

Electronic databases including The Cochrane Controlled Trials Register (The Cochrane Llibrary, Issue 2, 2002), MEDLINE (1966 - June 2002), EMBASE (1980 - June 2002) and CINAHL (1982 - June 2002) were searched by the strategy outlined in the protocol. Science Citation Index search for all articles which referenced Barnes 1982 were searched. The proceedings of the Pediatric Academic Societies which were published in the journal, Pediatric Research, from 1991 were searched as well as abstracts of the doctoral dissertations and theses from 1960. All of the above search strategies were completed in June 2002. Authors prominent in the field were contacted for any unpublished articles and more information on published articles was sought. Reference lists of identified clinical trials and personal files were also reviewed.

SELECTION CRITERIA

The criteria used to select studies for inclusion were: 1) DESIGN: randomised or quasi-randomised controlled trials 2) Hospitalised low birthweight infants with rotavirus infection 3) INTERVENTION: Oral immunoglobulin preparations compared to placebo OR no intervention 4) At least one of the following outcomes were reported: All cause mortality during hospital stay, mortality due to rotavirus infection during hospital stay, duration of diarrhoea, need for rehydration, duration of viral excretion, duration of infection control measures, length of hospital stay in days, recurrent diarrhoea or chronic diarrhoea

DATA COLLECTION AND ANALYSIS

The two reviewers were to independently abstract data from eligible trials. No data analysis was possible at this point.

MAIN RESULTS

No eligible randomised controlled trials were found.

REVIEWER'S CONCLUSIONS

We found no randomised controlled trials which assessed the effectiveness or safety of oral immunoglobulin preparations for the treatment of rotavirus infections in hospitalised low birthweight infants.