The mixtures were incubated at 42C (chicken body temperature) for different lengths of time

The mixtures were incubated at 42C (chicken body temperature) for different lengths of time. age (2, 4, or 6 weeks). The pH in gizzard slightly increased with age from 2.4 to 3.0, while the pH in the small intestine was around 5.8. ELISA analysis indicated that a short time of treatment (30 or 60 min) of IgY with the gizzard contents from the chickens at 2, 4, and 6 weeks of age greatly reduced specific IgY titer by over 8, 6, and 5 log2units, respectively, when compared with saline control. However, small intestine content only had a mild effect on egg yolk IgY, leading to 1 log2unit of reduction in IgY titer upon 30 min of treatment. Consistent with these findings, SDS-PAGE and immunoblotting analyses provided direct evidence demonstrating that egg yolk IgY could be drastically degraded to undetectable level in gizzard content upon as short as 5 min of treatment; however, the IgY was only slightly degraded in small intestine content. Immunoblotting also showed that treatment of IgY with HCl (pH 3.0) for 60 min did not affect its integrity at all, further supporting the enzymatic degradation of IgY in gizzard. Collectively, egg yolk IgY could be substantially degraded in chicken gizzard, highly warranting the development of effective approaches, such as encapsulation, for the controlled release and protection of orally administered egg yolk IgY in livestock. Keywords:egg yolk antibody, passive immunization, IgY stability, chicken gizzard, gastrointestinal digestion == Introduction == Chicken immunoglobulin Y (IgY) is the functional equivalent of IgG in mammals and can be transferred from serum to yolk during egg formation. Egg yolk contains a large quantity of IgY that can confer passive immunity for chicks against pathogens, either at embryonic or post-hatching stage (1). Immunization of hens with a particular antigen could yield a 2′-Deoxyguanosine large amount of specific egg yolk IgY that has potential applications in 2′-Deoxyguanosine human and veterinary medicine (2). In particular, as an emerging alternative to antibiotics, egg yolk IgY has 2′-Deoxyguanosine drawn considerable research interest in recent decades due to several unique features (2). First, a laying hen is regarded as a cost-efficient bioreactor that can produce over 22.5 g of egg yolk IgY yearly with 2%10% being antigen-specific (3). In addition, collecting egg yolka non-invasive practiceis convenient and also favorable from an animal welfare perspective (3). Finally, egg yolk IgY is quite stable in a wide pH range (3.511) and under high temperatures (up to 70C), making it feasible for storage and processing as a feed supplement (2). Due to these enticing features of egg yolk IgY, numerous studies have been conducted to develop specific egg yolk IgY for the control of microbial infections in humans and animals (1). In these studies, egg yolk IgY was administrated to animal hostsviadifferent routes, depending on the infection sites of targeted pathogens. Oral administration through feed or drinking water is the most common and convenient approach, especially against enteric pathogens (1). However, thein vivostability and bioavailability of administered egg yolk IgY in the gastrointestinal (GI) tract have not been examined in most previous studies and are still largely unknown to date. Addressing this issue is critical for appropriately assessing the efficacy of orally administrated egg yolk IgY and for developing effective egg yolk IgY-based passive immune intervention strategies. Limitedin vitrodata are available concerning the stability of IgY in response PDGFD to pepsin (a gastric protease), trypsin (a protease in the small intestine), and low pH alone (46). It has been reported that the neutralizing activity of IgY against rotavirus was totally lost in a pepsin solution (pH 2) but largely retained in a trypsin solution (pH 8) (5). In addition, IgY was fairly stable under the pH ranging from 3.5 to 11 (6). However, thesein vitrostudies could not fully reflectin vivoconditions of.