Adjuvant effects of various lipopeptides and interferon-gamma on the humoral immune response of chickens

Effect of TLR agonist on infections bronchitis virus replication and cytokine expression in embryonated chicken eggs

Avian infectious bronchitis (IB) is an acute, highly infectious and contagious viral disease of chickens caused by avian infectious bronchitis virus (IBV) belonging to the genus Coronavirus and family Coronaviridae. It can affect all age groups of birds. The toll-like receptors (TLRs) are a major class of innate immune pattern recognition receptors that have a key role in immune response and defense against various infections.The TLRs are essential for initiation of innate immune responses and in the development of adaptive immune responses. An in ovo model was employed to study the antiviral activity of TLR ligands (Pam3CSK4, LPS and CpG ODN) on replication of IBV. It was hypothesized that optimum dose and specific timing of TLR ligands may reduce viral load of IBV in specific pathogen free (SPF) embryonated chicken eggs (ECEs). Further, the mechanism involved in the TLR-mediated antiviral response in chorioallantoic membrane (CAM) of ECEs was investigated. The ECEs of 9-11 days old were treated with different doses (high, intermediate and low) of TLR-2 (Pam3CSK4), TLR-4 (LPS) and TLR-21 (CpG ODN) ligands. In addition, to know the timing of TLR ligand treatment, six time intervals were analyzed viz. 36, 24 and 12 h prior to infection, time of infection (co-administration of TLR ligands and avian IBV) and 12 and 24 h post-IBV infection. For studying the relative expression of immuno-stimulatory genes (IFN-α, IFN-β, IFN-γ, IL-1β, iNOS and OAS) in CAM, TLR ligands were administered through intra-allantoicroute and CAM were collected at 4, 8 and 16 h post treatment. The results demonstrated that intermediate dose of all the three TLR ligands significantly reduced virus titers and used in the present study. However, the LPS reduced virus titer pre- and post-IBV infection but Pam3CSK4 and CpG ODN reduced only pre-IBV infection. Further analysis showed that TLR ligands induced IFN-γ, IL-1β and IFN stimulated genes viz. iNOS and OAS genes in CAM. The present study pointed towards the novel opportunities for rational design of LPS as immuno-stimulatory agent in chickens with reference to IBV. It may be speculated that in ovo administration of these TLR ligands may enhance resistance against viral infection in neonatal chicken and may contribute towards the development of more effective and safer vaccines including in ovo vaccines.

Comparative study of the adjuvant potential of four Th0 cytokines of flounder (Paralichthys olivaceus) on an E. tarda subunit vaccine

Cytokines have the potential as adjuvants for the application of vaccines in mammals. However, the adjuvant potential of teleost cytokines was limited. In the present work, the adjuvant effects of four recombinant cytokines including IL-1β, IL-8, TNF-α and G-CSF on E. tarda subunit vaccine rOmpV were comparatively investigated in flounder (Paralichthys olivaceus). Compared with control, the levels of specific serum antibodies and IgM + B lymphocytes were significantly enhanced by rIL-1β, rIL-8 and rG-CSF, whereas rIL-1β and rIL-8 induced significantly higher levels than rG-CSF. All four cytokines enhanced the expression of genes involved in humoral and/or cellular immunities, whereas rIL-1β and rIL-8 induced highest levels of genes involved in humoral immunities and cellular immunities, respectively. Compared to the relative percent survivals (RPS) of control group (40%) and rOmpV plus rG-CSF group (54%), rOmpV plus rIL-1β or rIL-8 produced higher RPS of 75% and 68%, respectively. Our results indicated that rIL-1β and rIL-8 are promising adjuvants for subunit vaccines against E. tarda.

Synergistic effect of co-stimulation of membrane and endosomal TLRs on chicken innate immune responses

Toll-like receptor (TLR) ligands (TLR-Ls) are critical activators of immunity and are successfully being developed as vaccine adjuvants in both mammals and birds. In this study, we investigated the synergistic effect of co-stimulation of membrane and endosomal TLRs on the innate immune responses using chicken bone marrow-derived macrophages (BMMs), and studied the effect of age on the induction of innate responses. BMMs from 1 and 4-week-old birds were stimulated with Pam3Cys-SK4 (PCSK; TLR2), synthetic monophosphoryl lipid A (MPLA), Di[3-deoxy-d-manno-octulosonyl]-lipid A ammonium salt (KLA; TLR4), Gardiquimod, Resiquimod (R848; TLR7), CpG class B and C (TLR21). Nitric oxide (NO) production and mRNA levels of IL-1β, IL-10 and IL-12p40 showed macrophages from 4-week-old birds showed more sensitive responses compared to 1-week-old birds. The most potent TLR-Ls, PCSK, MPLA and CpG B were used to study the effect of co-stimulation on macrophages. Co-stimulation with TLR21 and TLR4 synergistically up-regulated inflammatory-related genes, as well as NO production. However, incubation of splenocytes with PCSK, MPLA and CpG B did not induce cell proliferation. Moreover, treatment with CpG B led to significant cell death.

Chicken egg yolk antibodies (IgY) as non-antibiotic production enhancers for use in swine production: a review

In recent years, the use of in-feed antibiotics for growth and disease prevention in livestock production has been under severe scrutiny. The use and misuse of in-feed antibiotics has led to problems with drug residues in animal products and increased bacterial resistance. Chicken egg yolk antibodies (IgY) have attracted considerable attention as an alternative to antibiotics to maintain swine health and performance. Oral administration of IgY possesses many advantages over mammalian IgG such as cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of swine diarrhea diseases and speculates on the future of IgY technology. Included are a review of the potential applications of IgY in the control of enteric infections of either bacterial or viral origin such as enterotoxigenic Escherichia coli, Salmonella spp., rotavirus, porcine transmissible gastroenteritis virus, and porcine epidemic diarrhea virus. Some potential obstacles to the adoption of IgY technology are also discussed.

Chicken egg yolk antibodies (IgY) as non-antibiotic production enhancers for use in swine production: a review

In recent years, the use of in-feed antibiotics for growth and disease prevention in livestock production has been under severe scrutiny. The use and misuse of in-feed antibiotics has led to problems with drug residues in animal products and increased bacterial resistance. Chicken egg yolk antibodies (IgY) have attracted considerable attention as an alternative to antibiotics to maintain swine health and performance. Oral administration of IgY possesses many advantages over mammalian IgG such as cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of swine diarrhea diseases and speculates on the future of IgY technology. Included are a review of the potential applications of IgY in the control of enteric infections of either bacterial or viral origin such as enterotoxigenic Escherichia coli, Salmonella spp., rotavirus, porcine transmissible gastroenteritis virus, and porcine epidemic diarrhea virus. Some potential obstacles to the adoption of IgY technology are also discussed.

Highly sensitive detection of cancer antigen human epidermal growth factor receptor 2 using novel chicken egg yolk immunoglobulin

Human epidermal growth factor receptor 2 (HER2) is an important biomarker that plays a crucial role in therapeutic decision-making for breast cancer patients. Ensuring the accuracy and reproducibility of HER2 assays by enzyme-linked immunosorbent assay (ELISA), western blot and immunohistochemistry (IHC) requires high sensitive and specific antibodies. Immunoglobulin Y (IgY) is a kind of avian antibody usually isolated from chicken egg yolks. Generation and use of IgY is of increasing interest in a wide variety of applications within the life sciences. In this study, IgY antibodies against two different truncated proteins of the extracellular domain (ECD) of human HER2 were produced, their sensitivity and specificity were evaluated. Specific IgYs were produced by hens immunized with the ECD proteins of human HER2 in long-standing immunization response and were isolated from yolks with a purity of 90% by water dilution, salt precipitations and ultrafiltration. The anti-HER2 IgYs were analytically validated for specificity by ELISA, western blot, immunocytochemistry and IHC. The IgYs bound desired targets in cells and fixed tissues and showed high affinity to HER2. The results demonstrated the viability of detection of HER2 with IgYs and showed promise for the using of IgYs in strict clinical validation.

Targeting TLR2 for vaccine development

Novel and more effective immunization strategies against many animal diseases may profit from the current knowledge on the modulation of specific immunity through stimulation of innate immune receptors. Toll-like receptor (TLR)2-targeting formulations, such as synthetic lipopeptides and antigens expressed in fusion with lipoproteins, have been shown to have built-in adjuvant properties and to be effective at inducing cellular and humoral immune mechanisms in different animal species. However, contradictory data has arisen concerning the profile of the immune response elicited. The benefits of targeting TLR2 for vaccine development are thus still debatable and more studies are needed to rationally explore its characteristics. Here, we resume the main features of TLR2 and TLR2-induced immune responses, focusing on what has been reported for veterinary animals.

Immunity to Marek's disease: where are we now?

Marek's disease (MD) in chickens was first described over a century ago and the causative agent of this disease, Marek's disease virus (MDV), was first identified in the 1960's. There has been extensive and intensive research over the last few decades to elucidate the underlying mechanisms of the interactions between the virus and its host. We have also made considerable progress in terms of developing efficacious vaccines against MD. The advent of the chicken genetic map and genome sequence as well as development of approaches for chicken transcriptome and proteome analyses, have greatly facilitated the process of illuminating underlying genetic mechanisms of resistance and susceptibility to disease. However, there are still major gaps in our understanding of MDV pathogenesis and mechanisms of host immunity to the virus and to the neoplastic events caused by this virus. Importantly, vaccines that can disrupt virus transmission in the field are lacking. The current review explores mechanisms of host immunity against Marek's disease and makes an attempt to identify the areas that are lacking in this field.

Immunostimulatory properties of Toll-like receptor ligands in chickens

Toll-like receptors (TLRs) are evolutionarily conserved pattern recognition receptors that have been identified in mammals and avian species. Ligands for TLRs are typically conserved structural motifs of microorganisms termed pathogen-associated molecular patterns (PAMPs). Several TLRs have been detected in many cell subsets, such as in macrophages, heterophils and B cells, where they mediate host-responses to pathogens by promoting cellular activation and the production of cytokines. Importantly, TLR ligands help prime a robust adaptive immune response by promoting the maturation of professional antigen presenting cells. These properties make TLR ligands an attractive approach to enhance host-immunity to pathogens by administering them either prophylactically or in the context of a vaccine adjuvant. In this review, we discuss what is known about the immunostimulatory properties of TLR ligands in chickens, both at the cellular level as well as in vivo. Furthermore, we highlight previous successes in exploiting TLR ligands to protect against several pathogens including avian influenza virus, Salmonella, Escherichia coli, and Newcastle disease Virus.

Diagnostics of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) nucleocapsid antigen using chicken immunoglobulin Y

The goal of this study was to develop a quantitative detection system for severe acute respiratory syndrome-associated coronavirus (SARS-CoV), targeting the nucleocapsid protein (NP), to determine the presence and degree of infection in suspected individuals. Because the NP is the viral protein shed during infection and its template mRNA is the most abundant subgenomic RNA, it is a suitable candidate for developing antibodies for diagnostic applications. In this study, we have prepared full-length SARS-CoV NP expressed in Escherichia coli and purified. Full-length NP was used for the preparation of mouse monoclonal antibody and chicken polyclonal IgY antibodies for the development of heterosandwich ELISA for early diagnostics of SARS-suspected individuals. The sensitivity of the developed heterosandwich ELISA can detect the viral antigen at 18.5 pg/mL of recombinant NP. This study describes ultrasensitive ELISA using 19B6 monoclonal antibody as the capture antibody and IgY as the detecting antibody against the most abundant SARS-CoV NP antigens. One of the most important findings was the use of inexpensive polyclonal IgY antibody to increase the sensitivity of the detection system for SARS-CoV at the picogram level. Furthermore, the immunoassay of SARS-CoV NP antigen developed could be an effective and sensitive method of diagnosing SARS-suspected individuals during a future SARS-CoV outbreak.

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

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.

Intestinal alkaline phosphatase detoxifies lipopolysaccharide and prevents inflammation in zebrafish in response to the gut microbiota

Vertebrates harbor abundant lipopolysaccharide (LPS) in their gut microbiota. Alkaline phosphatases can dephosphorylate and detoxify the endotoxin component of LPS. Here, we show that expression of the zebrafish intestinal alkaline phosphatase (Iap), localized to the intestinal lumen brush border, is induced during establishment of the gut microbiota. Iap-deficient zebrafish are hypersensitive to LPS toxicity and exhibit the excessive intestinal neutrophil influx characteristic of wild-type zebrafish exposed to LPS. Both of these Iap mutant phenotypes are dependent on Myd88 and Tumor Necrosis Factor Receptor (Tnfr), proteins also involved in LPS sensitivity in mammals. When reared germ-free, the intestines of Iap-deficient zebrafish are devoid of neutrophils. Together, these findings demonstrate that the endogenous microbiota establish the normal homeostatic level of neutrophils in the zebrafish intestine through a process involving Iap, Myd88, and Tnfr. Thus, by preventing inflammatory responses, Iap plays a crucial role in promoting mucosal tolerance to resident gut bacteria.

Preparation of immunoglobulin Y from egg yolk using ammonium sulfate precipitation and ion exchange chromatography

The objective of this study was to develop an economical, simple, and large-scale separation method for IgY from egg yolk. Egg yolk diluted with 9 volumes of cold water was centrifuged after adjusting the pH to 5.0. The supernatant was added with 0.01% charcoal or 0.01% carrageenan and centrifuged at 2,800 x g for 30 min. The supernatant was filtered through a Whatman no. 1 filter paper and then the filtrate was concentrated to 20% original volume using ultrafiltration. The concentrated solution was further purified using either cation exchange chromatography or ammonium sulfate precipitation. For the cation exchange chromatography method, the concentrated sample was loaded onto a column equilibrated with 20 mM citrate-phosphate buffer at pH 4.8 and eluted with 200 mM citrate-phosphate buffer at pH 6.4. For the ammonium sulfate precipitation method, the concentrated sample was twice precipitated with 40% ammonium sulfate solution at pH 9.0. The yield and purity of IgY were determined by ELISA and electrophoresis. The yield of IgY from the cation exchange chromatography method was 30 to 40%, whereas that of the ammonium sulfate precipitation was 70 to 80%. The purity of IgY from the ammonium sulfate method was higher than that of the cation exchange chromatography. The cation exchange chromatography could handle only a small amount of samples, whereas the ammonium sulfate precipitation could handle a large volume of samples. This suggests that ammonium sulfate precipitation was a more efficient and useful purification method than cation exchange chromatography for the large-scale preparation of IgY from egg yolk.

Expressions of Bovine IFN-γ and Foot-and-Mouth Disease VP1 antigen in P. pastoris and their effects on mouse immune response to FMD antigens

As a highly contagious disease in cloven-hoofed animals, foot-and-mouth disease virus (FMDV) may cause a considerable social-economic loss in those countries affected. IFN-gamma has a wide range of antiviral and immune modulating functions. Thus, to study the immune enhancing effects of recombinant Bovine IFN-gamma (rBoIFN-gamma) on a recombinant FMDV vaccine, BoIFN-gamma, FMDV VP1 and BoIFN-gamma/VP fusion genes were cloned, expressed, co-expressed in pichia pastoris (P. pastoris) respectively, and subsequent immune effects have been evaluated in this study. The results showed that the genes encoding for BoIFN-gamma, VP1 and BoIFN-gamma/VP1 are successfully expressed in P. pastoris and their products are directly secreted into the cultural supernatant at a high level of 1.0 g/L analyzed by thin-layer scanning. In addition, rVP1 alone could induce both humoral and marginal cell-mediated immune responses in mice, while the group with co-inoculations of rBoIFN-gamma could markedly enhance both humoral and cell-mediated immune responses; even more dramatic immune responses were observed with the group inoculated with the fusion product, rBoIFN-gamma/VP1. The fusion product could be further investigated for its utility of FMDV vaccine development.

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.

Generation and application of chicken egg-yolk antibodies

Despite the fact that the use of chicken as immunization host brings many advantages to the production of polyclonal antibodies, the generation of egg yolk immunoglobulins (IgY) is rarely chosen. In this review, we report on the fast and efficient method for generation and affinity purification of IgY, in this case raised against the alpha-subunit of hypoxia-inducible factor-1 (HIF-1). The IgY antibody was successfully applied in a variety of methods and a number of different species for HIF-1alpha detection. In electrophoretic mobility shift assays, the IgY antibody recognized the native HIF-1 complex. The IgY antibody also detected HIF-1alpha protein on Western blots with extracts derived from human, monkey, pig, dog and mouse cell lines grown under hypoxic conditions. Immunofluorescence and immunoprecipitation experiments using the IgY antibody allowed detection and subcellular localization of HIF-1alpha in the nuclei of hypoxic cells. Chicken antibody production brings great benefit concerning the welfare of the immunized animals, due to non-invasive antibody harvesting with the added convenience of simple egg collection. An additional advantage is the fast and simple IgY isolation from egg yolk. IgY technology is a great improvement and should be considered as a good alternative to conventional polyclonal antibody production in mammals.

Cytokines of birds: conserved functions--a largely different look

Targeted disruptions of the mouse genes for cytokines, cytokine receptors, or components of cytokine signaling cascades convincingly revealed the important roles of these molecules in immunologic processes. Cytokines are used at present as drugs to fight chronic microbial infections and cancer in humans, and they are being evaluated as immune response modifiers to improve vaccines. Until recently, only a few avian cytokines have been characterized, and potential applications thus have remained limited to mammals. Classic approaches to identify cytokine genes in birds proved difficult because sequence conservation is generally low. As new technology and high throughput sequencing became available, this situation changed quickly. We review here recent work that led to the identification of genes for the avian homologs of interferon-alpha/beta (IFN-alpha/beta) and IFN-gamma, various interleukins (IL), and several chemokines. From the initial data on the biochemical properties of these molecules, a picture is emerging that shows that avian and mammalian cytokines may perform similar tasks, although their primary structures in most cases are remarkably different.