Yu-Hong Zhen

Application of chicken egg yolk immunoglobulins in the control of terrestrial and aquatic animal diseases: a review.

Abstract Oral administration of chicken egg yolk immunoglobulin (IgY) has attracted considerable attention as a means of controlling infectious diseases of bacterial and viral origin. Oral administration of IgY possesses many advantages compared with mammalian IgG including cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of terrestrial and aquatic animal diseases and speculates on the future of IgY technology. Included are a review of the potential application of IgY for the treatment of livestock diseases such as mastitis and diarrhea, poultry diseases such as Salmonella, Campylobacteriosis, infectious bursal disease and Newcastle disease, as well as aquatic diseases like shrimp white spot syndrome virus, Yersina ruckeri and Edwardsiella tarda. Some potential obstacles to the adoption of IgY technology are also discussed.

Characterization of specific egg yolk immunoglobulin (IgY) against mastitis-causing Escherichia coli

The objective of this study was to estimate the in vitro activity of egg yolk immunoglobulin (IgY) against mastitis-causing Escherichia coli. Specific IgY was produced by hens immunized with formaldehyde killed E. coli O111 in long-standing immunization response (titer > or =6400 for 100 days) and was isolated from yolks with a purity of 86% by water dilution, salt precipitations and ultrafiltration. Enzyme-linked immunosorbent assay (ELISA) indicated the produced IgY specifically targeted E. coli O111 and five other E. coli strains which were isolated from mastitic cows. The growth inhibition activity of the specific IgY to bacteria was dose-dependent with an effective concentration of 20mg purified IgY per milliliter. The phagocytic activity of E. coli either by milk macrophages (MPhi) or by polymorphonuclear neutrophil leukocytes (PMN) in the presence of specific IgY was significantly higher than that with nonspecific IgY or without IgY (p<0.05), suggesting that it enhanced phagocytic activity. The current work suggests that this specific IgY has potential as a therapeutic treatment for mastitis in dairy cows.

Efficacy of specific egg yolk immunoglobulin (IgY) to bovine mastitis caused by Staphylococcus aureus.

The objective of this study was to estimate the efficacy of specific egg yolk immunoglobulin (IgY) to bovine mastitis caused by Staphylococcus aureus. Eighteen lactating cows with clinical mastitis and 18 lactating cows with experimental mastitis (1 quarter per cow) were randomly assigned to three treatments: IgY (20mg/ml) infusion, penicillin (100mg/ml) infusion and no infusion. Treatments for clinical mastitis and experimental mastitis were performed by a 6-day course of intramammary infusion with a dosage of 10ml at an interval of 12h. Milk samples were collected at morning milking time for testing color, clot, somatic cell counts (SCC) and bacterial count. For most of the cows treated with IgY and penicillin, the milk color and clot recovered to normal form during the therapy course. The milk SCCs and bacterial counts of treated cows decreased compared to those of untreated cows (p<0.05). The cure rates by IgY for experimental and clinical mastitis were 83.3% and 50%, respectively, and those by penicillin were 66.7% and 33.3%, respectively. These results showed the potential of specific IgY to be an alternative therapy for mastitis caused by S. aureus.

Chitosan-alginate microcapsules for oral delivery of egg yolk immunoglobulin (IgY): in vivo evaluation in a pig model of enteric colibacillosis.

In our previous study, the applicability of chitosan-alginate microcapsules for oral delivery of egg yolk immunoglobulin (IgY) was established in a simulated gastrointestinal tract environment. The objective of the present study was to evaluate the protective efficacy of microencapsulated IgY against K88+ ETEC (enterotoxigenic Escherichia coli)-induced diarrhea in 40-day-old pigs. Groups of pigs orally challenged with 10(11) cfu/mL of K88+ ETEC were fed with non-encapsulated IgY, microencapsulated IgY and aureomycin-treated feed respectively. The clinical response of each group was monitored and evaluated in terms of lethargy, inappetence, occurrence of diarrhea, fecal consistency score, weight loss and recovery rate. The results showed that treatment of infected pigs with microencapsulated IgY significantly (P<0.05) reduced the K88+ ETEC-induced diarrhea at 24 h post-infection. In contrast, the diarrhea-reducing effect of non-encapsulated IgY was delayed (only evident after 72 h) while normal saline-treated pigs (controls) continued to suffer from diarrhea and dehydration. Similarly, weight gain in microencapsulated IgY-treated pigs was better and significantly different (P<0.05) than in non-encapsulated IgY and saline-treated controls. Collectively, these results support previous in vitro observations showing that chitosan-alginate microcapsules can be an effective method of protecting IgY from gastric inactivation, enabling its use for the widespread prevention and control of enteric diseases.

Passive protection of shrimp against white spot syndrome virus (WSSV) using specific antibody from egg yolk of chickens immunized with inactivated virus or a WSSV-DNA vaccine.

White spot syndrome virus (WSSV) causes high mortality and large economic losses in cultured shrimp. The VP28, VP19 and VP15 genes encode viral structural proteins of WSSV. In this study, hens were immunized with recombinant plasmid (pCI-VP28/VP19/VP15) with linkers or with inactivated WSSV, which used CpG oligodeoxynucleotides (CpG ODNs) and Freunds adjuvant as adjuvant, respectively. Egg yolk immunoglobulin (IgY) from hens immunized with inactivated vaccine and DNA vaccine was obtained, purified and used for protection of Metapenaeus ensis shrimp against WSSV. The data showed that the antibody response of the hens immunized with the DNA vaccine was improved by CpG ODNs as adjuvant, but was still inferior to inactivated WSSV in both sera and egg yolks. Using specific IgY from hens immunized with inactivated WSSV and DNA vaccine to neutralize WSSV, the challenged shrimp showed 73.3% and 33.3% survival, respectively. Thus, the results suggest that passive immunization strategy with IgY will be a valuable method against WSSV infection in shrimp.

Characterization of specific egg yolk immunoglobulin (IgY) against mastitis-causing Staphylococcus aureus.

Aims:  To evaluate the in vitro activity of egg yolk immunoglobulin (IgY) against mastitis‐causing Staphylococcus aureus.

Passive Immunization of Crayfish (Procambius clarkiaii with Chicken Egg Yolk Immunoglobulin (IgY) Against White Spot Syndrome Virus (WSSV)

White spot syndrome virus (WSSV) is a major cause of mortality in shrimp lacking a true adaptive immune response. In this study, high activity egg yolk immunoglobulin (IgY) against WSSV for passive immunization of crustaceans was already prepared as crude and purified product, while an indirect enzyme-linked immunosorbent assay test was used for quality control of IgY activity. The effectiveness of IgY of intramuscular injection, oral administration, and immersion was investigated in crayfish (Procambius clarkiaii) against WSSV. The result showed that the groups treated with IgY from inactivated WSSV and DNA vaccine were, respectively, 20% and 80% mortality, which were significant difference in survival rates (P < 0.05) from the positive control groups. The groups in diet added 10% egg yolk powder and 1% IgY power showed 53.3% and 67.7% mortality, respectively, and the immersion showed 46.7% mortality, which have significantly different compared to the positive groups (P < 0.05). These results indicated passive immunization of specific IgY antibodies through intramuscular injection, oral administration, and immersion have effective to protect crayfish against WSSV. It is noteworthy that IgY as feed additive and immersion solution is useful and feasible methods in practical work. Thus, our results suggest that the passive immunization of crayfish with IgY against WSSV will have potential development to prevent and control WSSV in practical culture.

Efficacy of specific IgY for treatment of lipopolysaccharide-induced endotoxemia using a mouse model

Aims:  To estimate the efficacy of specific egg yolk immunoglobulin (IgY) for the treatment of lipopolysaccharide (LPS)‐induced endotoxemia using a mouse model.

Chitosan–Alginate Microcapsules for Oral Delivery of Egg Yolk Immunoglobulin (IgY): Effects of Chitosan Concentration

In our previous study, chitosan–alginate microcapsules were developed to protect egg yolk immunoglobulin (IgY) from gastric inactivation. The present study was undertaken to determine the effect of chitosan concentration (0–0.8%; w/v) on various properties of the microcapsules in order to produce the optimum chitosan–alginate microcapsules for use in the oral delivery of IgY. The properties investigated included microcapsule morphology, loading capacity for IgY (expressed as the IgY loading percentage, w/w, of microcapsules), encapsulation efficiency (EE%), in vitro gastroresistance, and IgY release. IgY loading percentage and EE% were both highest at 0.2% (w/v) chitosan, and, above this level, further increases were not observed. The stability of IgY in simulated gastric fluid (pH 1.2) was significantly improved by encapsulation in alginate microcapsules (IgY retained 43.5% of its activity) and was further improved by including chitosan at any of the chitosan concentrations assessed (IgY retained an average of 69.4% activity) although there was no difference in protection of gastric inactivation among concentrations of chitosan varying from 0.05% to 0.8% (w/v). Higher chitosan concentrations (i.e., ≥0.2%; w/v) prolonged the release of IgY from the microcapsules during simulated intestinal fluid incubation (pH 6.8). However, above the 0.2% (w/v) level, no significant differences were observed. We conclude that the optimum chitosan concentration for microencapsulation is 0.2% (w/v).