Comparison between ‘IgY technology’ from chickens and ‘IgG technology’ from mice for production of tailor-made antibodies

An IgY Effectively Prevents Goslings from Virulent GAstV Infection

Goose astrovirus (GAstV) leads to viscera and joints urate deposition in 1- to 20-day-old goslings, with a mortality rate of up to 50%, posing a severe threat to entire colonies; however, there is no efficient prevention and control method for GAstV infection. This study describes a prophylactic anti-GAstV strategy based on the specific immunoglobulin Y (IgY) from egg yolk. The specific IgY was produced by 22-week-old laying hens intramuscularly immunized with the inactivated GAstV three consecutive times, with 2-week intervals. The egg yolk was collected weekly after the immunization and the anti-GAstV IgY titer was monitored using an agar gel immune diffusion assay (AGID). The results revealed that the AGID titer began to increase on day 7, reached a peak on day 49, and remained at a high level until day 77 after the first immunization. The specific IgY was prepared from the combinations of egg yolk from day 49 to day 77 through PEG-6000 precipitation. Animal experiments were conducted to evaluate the effects of prevention and treatment. The result of the minimum prophylactic dose of the IgY showed that the protection rate was 90.9% when 2.5 mg was administrated. Results of the prevention and the treatment experiments showed prevention and cure rates of over 80% when yolk antibody was administered in the early stages of the GAstV infection. These results suggested that the specific IgY obtained from immunized hens with the inactivated GAstV could be a novel strategy for preventing and treating GAstV infection.

Egg yolk immunoglobulin (IgY) targeting SARS-CoV-2 S1 as potential virus entry blocker

Aims

COVID‐19 pandemic caused by SARS‐CoV‐2 has become a public health crisis worldwide. In this study, we aimed at demonstrating the neutralizing potential of the IgY produced after immunizing chicken with a recombinant SARS‐CoV‐2 spike protein S1 subunit.

Methods and Results

E. coli BL21 carrying plasmid pET28a‐S1 was induced with IPTG for the expression of SARS‐CoV‐2 S1 protein. The recombinant His‐tagged S1 was purified and verified by SDS‐PAGE, Western blot and biolayer interferometry (BLI) assay. Then S1 protein emulsified with Freund's adjuvant was used to immunize layer chickens. Specific IgY against S1 (S1‐IgY) produced from egg yolks of these chickens exhibited a high titer (1:25,600) and a strong binding affinity to S1 (K_D = 318 nmol L⁻¹). The neutralizing ability of S1‐IgY was quantified by a SARS‐CoV‐2 pseudotyped virus‐based neutralization assay with an IC₅₀ value of 0.99 mg ml⁻¹. In addition, S1‐IgY exhibited a strong ability in blocking the binding of SARS‐CoV‐2 S1 to hACE2, and it could partially compete with hACE2 for the binding sites on S1 by BLI assays.

Conclusions

We demonstrated here that after immunization of chickens with our recombinant S1 protein, IgY neutralizing antibodies were generated against the SARS‐CoV‐2 spike protein S1 subunit; therefore, showing the potential use of IgY to block the entry of this virus.

Significance and Impact of the Study

IgY targeting S1 subunit of SARS‐CoV‐2 could be a promising candidate for pre‐ and post‐exposure prophylaxis or treatment of COVID‐19. Administration of IgY‐based oral preparation, oral or nasal spray may have profound implications for blocking SARS‐CoV‐2.

Can Immunization of Hens Provide Oral-Based Therapeutics against COVID-19?

In the current worldwide pandemic situation caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and the newest coronavirus disease (COVID-19), therapeutics and prophylactics are urgently needed for a large population. Some of the prophylaxis strategies are based on the development of antibodies targeting viral proteins. IgY antibodies are a type of immunoglobulin present in birds, amphibians, and reptiles. They are usually obtained from egg yolk of hyper-immunized hens and represent a relatively inexpensive source of antibodies. Specific IgY can be produced by immunizing chickens with the target antigen and then purifying from the egg yolk. Chicken IgY has been widely explored as a clinical anti-infective material for prophylaxis, preventive medicine, and therapy of infectious diseases. Administered non-systemically, IgY antibodies are safe and effective drugs. Moreover, passive immunization with avian antibodies could become an effective alternative therapy, as these can be obtained relatively simply, cost-efficiently, and produced on a large scale. Here, we highlight the potential use of polyclonal avian IgY antibodies as an oral prophylactic treatment for respiratory viral diseases, such as COVID-19, for which no vaccine is yet available.

Antibacterial activity of egg yolk antibody (IgY) against Listeria monocytogenes and preliminary evaluation of its potential for food preservation

BACKGROUND

Egg yolk antibody (IgY) is a unique type of immunoglobulin found in egg yolks, and many reports have described its ability to inhibit corresponding antigen bacteria. The objective of this study was to evaluate the antibacterial activity of IgY specific to Listeria monocytogenes, an important food pathogen to both humans and animals, as well as its potential use for food preservation.

RESULTS

Specific IgY was generated by immunising Leghorn chickens with whole cells of L. monocytogenes, and its inhibitory effect on bacterial growth was tested in liquid medium and food samples. After 8 h of incubation with specific IgY, there was a significant decrease in the growth (absorbance at 600 nm) of L. monocytogenes in comparison with controls. IgY also inhibited the growth of L. monocytogenes inoculated onto fresh or smoked salmon samples. Compared with those of blanks, numbers of L. monocytogenes were reduced by more than 2 log units after 15 days of storage at 6 ± 1 °C in the presence of specific IgY.

CONCLUSION

The results suggest the potential application of specific IgY as a natural antimicrobial agent for food preservation.

Preparation of immunoglobulin Y (IgY) against lipopolysaccharide using gel chromatography from the yolks of eggs laid by immunized hens

The objective is to prevent and treat injuries caused by lipopolysaccharide (LPS) from gram negative bacteria in animals and humans, we produced antibodies against LPS from egg yolk. LPS from E. coli (O111:B4) mixed with Freund's Adjuvant was used as the immunogen to immunize Roman hens. Immunized eggs were collected, and immunoglobulin Y (IgY) was purified using a water solution, salt precipitation and gel chromatography. The molecular weight and purity were determined by SDS-PAGE, the antibody titer by noncompetitive enzyme-linked immunosorbent assay (ELISA) and antibody activity against LPS by the mortality of mice intraperitoneally injected with LPS or LPS-IgY solutions. IgY against LPS showed two protein bands at 68 and 26 kDa on the gel; the antibody titer was almost 1:25,600. After incubation with LPS, IgY decreased the mortality of mice challenged with LPS. This study provided an efficient way to produce high-titer egg yolk antibodies, which could attenuate lethal effects of LPS, by immunizing hens. Furthermore, the LPS antibody was purified well using a water solution, salting-out and gel chromatography.

In vitro reactivity and growth inhibition of EPEC serotype O111 and STEC serotypes O111 and O157 by homologous and heterologous chicken egg yolk antibody

IgY is a chicken egg yolk antibody which has been used for treatment and prophylaxis of gastrointestinal infections. Our aim was to verify if IgY obtained from chickens immunized with EPEC O111, STEC O111 and STEC O157 is able to show in vitro reactivity and biological activity towards the three bacteria. IgY was obtained from eggs laid before and after immunization with each bacterium. The preparations of IgY anti-EPEC O111 and anti-STEC O111 shared high reactivity detected by ELISA and growth inhibition ability towards both bacteria EPEC O111 and STEC O111. Nevertheless, the preparation of IgY anti-STEC O157 showed high reactivity and growth inhibitory effect only towards the homologous strain. Our results showing in vitro biological activity of IgY reinforce its use as an alternative for the treatment or prophylaxis of E. coli infections and encourage the development of in vivo studies for a possible future human therapeutic use.

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.

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.