The chicken immune system has been studied for many years and these studies have contributed substantially to our understanding of the fimdamental concepts of immunology and the development of different immunoglobulin classes It is thus surprising that only a small fraction of the antibodies presently used in laboratories are of avian origin A laying hen produces more yolk antibodies than a rabbit can produce during the same time period, and the animal care costs are lower for the chicken compared to the rabbit Chicken antibodies offer many advantages to the traditional mammalian antibodies when used for the detection of mammalian antigen Due to the evolutionary difference chicken IgY will react with more epitopes on a mammalian antigen, which will give an amplification of the signal Chicken antibodies can also be used to avoid interference in immunological assays caused by the human complement system, rheumatoid factors, human anti-mouse IgG antibodies (HAMA) or human and bacterial Fc-receptors The antibodies can be purified in large amounts from egg yolk, making laying hens highly efficient producers of polyclonal antibodies IgY is an ancestor to mammalian IgG and IgE and also to IgA. ANTIBODY DIVERSITYThe antibody diversity in chicken differ from mammals and is mainly due to somatic hyperconversion. Rearrangement apparently contributes little to the diversity as both the heavy and the light chain loci consist of only one functional V gene (38,44). There seems to be a deficiency in the mechanism for selecting higher-affinity somatic mutants.Chicken antibody has the valency of 2.0 and sometimes higher which might be due to large antigen-binding sites (43). Most chicken IgY bind antigen strongly but display precipitation properties only at raised salt concentrations (16). The poor precipitation properties might be due to steric hindrance of the Fab arms to crosslink epitopes of two large antigens. The conditions permitting precipitation (salt -1.5 M) might loosen the restricted movement of the Fab arms and give functional independence to the binding sites. I80 ADVANTAGES OF CHICKEN ANTIBODIESAs the difference between the antigen and the immunized animal increases, the immune response usually increases. There is a vast phylogenetic difference between avian and mammalian species compared to the difference between two mammalian species. This evolutionary spread means that there is no immunological cross-reactivity between chicken IgY and mammalian IgG (18). Thus, chicken should be a better choice than e.g. rabbits for the production of antibodies against mammalian proteins. Due to evolutionary differences chicken antibodies will bind to more epitopes on a mammalian protein than the corresponding mammalian antibody. It has been shown that 3-5 times more chicken antibody than swine antibody will bind to rabbit IgG (1 7), which will amplify the signal (35). Chicken antibodies also recognize other epitopes than mammalian antibodies (41).This gives access to a different antibody repertoire than the traditional m...

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Background P. aeruginosa is a pathogen frequently resistant to antibiotics and a common cause of ventilator-associated pneumonia (VAP). Non-antibiotic strategies to prevent or treat VAP are therefore of major interest. Specific polyclonal avian IgY antibodies have previously been shown to be effective against pneumonia caused by P. aeruginosa in rodents and against P. aeruginosa airway colonization in patients. Objectives To study the effect of specific polyclonal anti- P. aeruginosa IgY antibodies ( Pa- IgY) on colonization of the airways in a porcine model. Method The pigs were anesthetized, mechanically ventilated, and subject to invasive hemodynamic monitoring and allocated to either receive 10 9 CFU nebulized P. aeruginosa (control, n = 6) or 10 9 CFU nebulized P. aeruginosa + 200 mg Pa- IgY antibodies (intervention, n = 6). Physiological measurement, blood samples, and tracheal cultures were then secured regularly for 27 h, after which the pigs were sacrificed and lung biopsies were cultured. Results After nebulization, tracheal growth of P. aeruginosa increased in both groups during the experiment, but with lower growth in the Pa- IgY-treated group during the experiment ( p = 0.02). Tracheal growth was 4.6 × 10 3 (9.1 × 10 2 –3.1 × 10 4 ) vs. 4.8 × 10 4 (7.5 × 10 3 –1.4 × 10 5 ) CFU/mL in the intervention group vs. the control group at 1 h and 5.0 × 10 0 (0.0 × 10 0 –3.8 × 10 2 ) vs. 3.3 × 10 4 (8.0 × 10 3 –1.4 × 10 5 ) CFU/mL at 12 h in the same groups. During this time, growth in the intervention vs. control group was one to two orders of ten lower. After 12 h, the treatment effect disappeared and bacterial growth increased in both groups. The intervention group had lower body temperature and cardiac index and higher static compliance compared to the control group. Conclusion In this porcine model, Pa -IgY antibodies lessen bacterial colonization of the airways. Electronic supplementary material The online version of this article (10.1186/s40635-019-0246-1) contains supplementary material, which is available to authorized users.

Plasma calprotectin has previously been reported as a biomarker for sepsis. The aim of the present study was to elucidate the kinetics of calprotectin release from neutrophils exposed to Escherichia coli and endotoxin. Whole blood samples were exposed to E. coli bacteria or endotoxin in vitro. Blood samples were collected after 0, 1, 2, 3 and 4 h and plasma calprotectin was analysed by particle enhanced turbidimetric immunoassay while TNF-α, IL-6, neutrophil gelatinase-associated lipocalin (NGAL) and kidney injury molecule-1 (KIM-1) were analyzed by ELISA. When neutrophils were exposed to either E. coli or endotoxin, calprotectin levels began to increase within a couple of hours after the challenge. Calprotectin increases early in response to bacterial challenge. Given the logistic advantages of the calprotectin analysis, this may be of interest for early diagnosis of bacterial infections.

Egg yolk is an important source of antibodies. The biggest obstacle for isolation of chicken antibodies (IgY) is the removal of lipids, which are present in abundance in egg yolk. We have used a two-phase system to separate egg yolk. The use of an aqueous two-phase system with phosphate and Triton X-100 made separation of lipids and water-soluble proteins possible. Lipids are extracted into the detergentenriched top-phase, whereas IgY is isolated in the phosphate-enriched bottom-phase. The phosphate:triton system was characterised and optimised using various experimental designs. For the optimised model, the yield of IgY was kept above 97% (11.1-14.9 mg IgY/g egg yolk recovered). The amount of lipids in the bottom-phase was kept below 25% of the total content in the egg yolk added. Hence, the model described provides a method for extracting the IgY-fraction with a high yield and relatively low lipid content.