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Infectious bursa disease virus (IBDV) pathogenesis is characterized by increased numbers of T cells and decreased numbers of B cells in the bursa. Currently, little is about the key factor that affects T migration into bursa. In humans, CC chemokine ligand 19 (CCL19) recruits monocytes and neutrophils and is usually involved in various inflammatory disorders. The aim of this study was to assess the roles of CCL19 in driving peripheral blood cells infiltration into bursa of Fabricius of chickens infected with IBDV. Bursal samples were collected from chickens of the infection group and the control group on day 1, 3, 5, and 7 post infection (dpi) with IBDV. The mRNA or protein levels of ccl19 and ccr7 genes in bursae were determined by real-time PCR and immunohistochemistry (IHC) methods. Moreover, an in vitro chemotaxis assay was performed to evaluate the chemotaxis ability of CCL19 and bursal total protein. The results have displayed that the mRNA levels of ccl19 were significantly increased on 1, 3, 5, and 7 dpi in the infection group. The highest value amounted to 73.4-fold of the control group. Also, the mRNA levels of CCR7, the receptor of CCL19, began to increase on 3 dpi and reached to the highest value of 206.3-fold on 5 dpi after IBDV infection. Then the gene expression of CCR7 in bursae of the infection group returned to the normal level. IHC results of CCL19 protein level accorded with the mRNA levels of CCL19, with the highest value on 5 dpi. Then, in vitro chemotaxis test demonstrated that the total bursal protein had the ability of recruiting peripheral white blood cells (PWBC) and the migration percentage was a little higher than that of the blank control with only basal medium (P < 0.05). Taken together, these data suggest that CCL19 acts as a chicken PWBC chemotactic factor and facilitate the infiltration of PWBC (especially T cells) into the bursae after IBDV infection. [ABSTRACT FROM AUTHOR]

T lymphocytes and Toll-like receptors have been confirmed to have correlation with the ability to resistance to pathogenic challenges and play an important role in duck immune system. However, the information of ontogeny of T lymphocytes and Toll-like receptors is scarcely in duck. Therefore, to address these questions, we report the development and distribution of CD3 and CD4 by immunocytochemistry and the age-related mRNA level of duck T cell markers (CD3 and CD4) and Toll-like receptors (TLR2, TLR3, TLR4 and TLR7) by real time quantitative PCR in duck lymphoid organs (thymus, bursa of Fabricius and spleen). Results indicated that CD3 and CD4 positive cells can be observed in all test organs and partly change in an age-related way. CD4 positive T cell of duck spleen mainly distributed in periarterial lymphatic sheaths and red pulp, not in white pulp. Both of CD3 and CD4 were experienced significant increased wave twice in duck lymphoid organs and T cell dependent cellular immunity of duck may well established until 5 weeks old. The mRNA expression levels of duck TLRs were age and organ dependent, and duck TLR3 and TLR7 were significantly lower abundance in the spleen but higher in thymus and bursa of Fabricius, respectively. This study provide the essential knowledge of the ontogeny of T cells and Toll-like receptors in duck, which may shed lights on the T-cell mediate immunity and innate immunity in duck. [ABSTRACT FROM AUTHOR]

Background Chickens infected with both infectious bursal disease virus (IBDV) and Salmonella had higher mortality. In this work, we investigated the effect of IBDV vaccine (modified live-virus bursal disease vaccine, Nobilis strain 228E®) on experimentally infected chickens with Salmonella Enteritidis (SE). Methods Four experimental groups were included in this study, negative control group, 228E®group, 228E® + SE infected group, and SE infected group. Chickens were ocularly administrated 228E® at 12 days of age and orally infected with S. Enteritidis at 13 days of age. Sera, intestinal fluid, blood, cloacal swabs and tissue samples were collected at 1, 2 and 3 weeks post vaccination (PV). Results The recorded mortalities were higher in the 228E® + SE infected group, compared to the SE infected group. The anti- S. Enteritidis serum antibody titer and the intestinal mucosal IgA level were higher in the SE infected group at 2 and 3 weeks PV, compared to 228E® + SE infected group. S. Enteritidis fecal shedding and organ colonization were significantly higher in the 228E® + SE infected group than the SE infected group at 2 and 3 weeks PV. The 228E® + SE group had significantly lower bursa to body weight ratios at 2 and 3 weeks PV, as well as had higher bursal lesion scores than the SE infected group. IBDV vaccine depressed the specific-SE systemic and mucosal antibody responses, but did not affect the specific-SE cellular immune responses. Conclusion Chickens administrated IBDV vaccine, followed by S. Enteritidis infection, could cause a significant effect on the bursa of Fabricius, resulting in failure of systemic and mucosal antibody responses to the S. Enteritidis and reduce the elimination and the clearance of S. Enteritidis. [ABSTRACT FROM AUTHOR]

Vaccination is recognized to be the most cost-effective means of preventing, controlling, and even eradicating infectious diseases. Conventional poultry are vaccinated through various routes including eye/nose drops, drinking water, vent brush, or injection. Efficient vaccination is an essential part of any good poultry management. The bursa of Fabricius is intimately connected to the cloaca and the intestinal system. It is well-known as a primary lymphoid organ in the chicken and a major channel through which environmental antigens stimulate the immune system. In this study we tested whether direct instillation of various viral vaccines and antigens into the cloaca (per bursam), could stimulate higher antibody titers and generate improved protection. Despite the very rapid absorption of the vaccines or antigens from the cloaca to the lumen of the Bursa of Fabricius, per bursam inoculation failed to generate a satisfactory immune response. In contrast conventional administration of live or inactivated commercial vaccines led to an acceptable level of seroconversion and protection against challenge. An interesting finding in this study was the fact that administration of a single priming dose of antigenic material at age 1 or 5 days, did not improve the response to a second administration at 14 days of age as expected. Instead, in most cases there was a reduced serum antibody response suggesting the induction of tolerance. This was true for all routes of administration (intramuscular, per ocular and per bursam) and for all formulations of vaccine. The current study reveals: 1) no advantage for direct application of live or inactivated vaccines or antigens into the bursa of Fabricius compared to common routes of vaccination, 2) that apparent desensitization or tolerance effects have important implications for poultry management, since in many countries, vaccination of day old chicks is compulsory or a well-accepted part of flock vaccination. According to our results, early vaccination can in fact reduce or inhibit a secondary immune response to subsequent vaccination and increase susceptibility to disease agents. [ABSTRACT FROM AUTHOR]

The bursa of Fabricius, the central humoral immune organ unique to birds, plays an important role in B-lymphocyte differentiation. In order to gain a better understanding of the molecular mechanism of critical biological processes like Bcell immigration, differentiation, and final emigration, the transcriptional changes during embryonic and posthatch development of this organ were investigated. We generated a cDNA library from total RNA isolated from 3 representative developmental stages (embryonic day [ED] 10, posthatch d 2 and d 21). We generated over 70 million high-quality reads from the cDNA library by using deep sequencing. The uniquely mapped sequences of ED 10, d 2 and d 21 were 71087280, 59167491 and 70263675 respectively. All of the differential expressed genes were involved in Vitamin A metabolism, regulation of actin cytoskeleton, Wnt signaling pathway, MAPK signaling pathway, Jak-STAT signaling pathway, Notch signaling pathway, Toll-like receptor signaling pathway. The RNA-seq analysis provides a powerful method for analyzing the transcriptome and investigating the transcriptional changes of different development stages of bursa of Fabricius. The assembled bursa transcriptome provides an essential resource for future investigations about chicken Bursa development. [ABSTRACT FROM AUTHOR]

Species of the family Prosthogonimidae are considered the most pathogenic poultry trematodes worldwide, affecting particularly low intensity farming in rural areas. Adults of Prosthogonimus occur mainly in the bursa of Fabricius, oviduct and cloaca of ducks, geese, fowl and other birds feeding at least occasionally on dragonflies or damselflies (Odonata). We analyzed the central European species of the Prosthogonimidae, namely Prosthogonimus cuneatus , Prosthogonimus ovatus , Prosthogonimus pellucidus and Prosthogonimus rarus . We sequenced three nuclear (ITS2) and mitochondrial (CO1, ND1) DNA loci of four species isolated from Anas clypeata , Anas strepera , Anas platyrhynchos , Aythya ferina , Passer domesticus and Turdus merula . Intra- and inter-specific sequence variability revealed that all four species represent distinct well-defined entities. Our data, combined with previously published studies, suggest the return of the name Prosthogonimus rarus Braun, 1901 for Schistogonimus rarus (Braun, 1901). The genus name Schistogonimus Lühe, 1909 is considered a junior synonym of Prosthogonimus Lühe, 1899. We identified the existence of two clades, one represented by P. cuneatus and P. pellucidus , and another one formed by P. ovatus and P. rarus . We also provide comparative measurements of these four central European prosthogonimids, and address their tissue specificity, host-specific prevalence (based on the extensive bird cohort examined in years 1962–2014), and for some bird hosts we address also differences in the prevalence of Prosthogonimus spp. in natural and near-natural wetlands in comparison with fishponds utilized for intense carp production. We provide an updated key to European Prosthogonimus spp. based on their morphological characters. [ABSTRACT FROM AUTHOR]

Several causes may induce change and atrophy in the bursa of Fabricius (BF). Databases on BF standards are available from published studies, however, updated references are needed to adjust the BF standards to present changes in highly specialized broiler genetic lines. The aim of this study was to evaluate BF-related measurements (weight and dimensions) under controlled conditions that would mimic field situations. Chickens were kept in isolation, thus avoiding exposure to disease agents by vaccination or field infections. This study was conducted using male Cobb 500 commercial broilers from the same hatch and source. Absence of disease was confirmed throughout the study. Despite the presence of individual variations, a minimum bursa-to-body weight ratio standard of 0.11 is proposed in broilers from 7 to 42 days of age. [ABSTRACT FROM AUTHOR]

Cells of the adaptive immune system express Toll-like receptors (TLRs) and are able to respond to TLR ligands. With this in mind, the goal of the current study was to determine the expression of antiviral response genes in the cells of the chicken bursa of Fabricius (BF) to stimulation with TLR ligands. We investigated initially the response of bursal B cells to CpG-ODN, lipopolysaccharide (LPS) and poly(I:C) treatment. The expression level of type I interferons (IFNs) and interferon regulatory factor 7 (IRF7) did not differ between CpG-ODN and LPS treated groups compared to the non-stimulated cells. Poly(I:C) was the only TLR ligand, which has induced significant expression of antiviral innate immune response genes from bursal cells. Further in vitro and in vivo studies need to examine the efficacy of these antiviral responses against avian viruses. [ABSTRACT FROM AUTHOR]

To study the role of melatonin in the monochromatic light-induced B lymphocyte proliferation of bursa, a total of 360 newly hatched broilers, including intact, sham-operated, and pinealectomized groups, were exposed to blue light (BL), green light (GL), red light (RL) and white light (WL) from a light-emitting diode system for 14 d . Both in vivo and in vitro studies showed that the percentage of proliferating cell nuclear antigen (PCNA)-immunoreactive lymphocytes and the lymphocyte proliferation in response to lipopolysaccharide in the bursa of broilers in the GL intact group was the highest values among the different intact groups with altered plasma melatonin levels. Additionally, the superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and total antioxidant capability (T-AOC) were the highest, whereas malondialdehyde (MDA) content and inducible nitric oxide synthase (iNOS) expression were significantly decreased in the GL intact group. After pinealectomy, the levels of SOD, GSH-Px and T-AOC decreased remarkably in the various light-treatment groups, whereas the MDA content and iNOS expression significantly increased. The administration of exogenous melatonin (250 pg/mL) in vitro also significantly enhanced the bursal B lymphocyte proliferation. These findings suggest that GL illumination effectively elevates the antioxidative capacity to promote B lymphocyte proliferation of bursa in young broilers, which might depend on enhanced melatonin secretion. [ABSTRACT FROM AUTHOR]

This article outlines the fundamental contribution of Max D. Cooper to the analysis of the role of the thymus and of the bursa of Fabricius in the development of immunologic competence both before and after birth, placing a new scientific paradigm in the definition of the ontogeny of the lymphoid tissues. [ABSTRACT FROM AUTHOR]

Background Avian leukosis virus subgroup J (ALV-J) causes tumours and immunosuppression in chickens. The host-ALV interactions at the transcriptional level are unknown. In this study, gene expression profiling was performed to analyse the bursa response induced by ALV-J strain JS09GY3 in chickens. Results A total of 594 gene transcripts displaying differential expression during ALV-J infection were identified. These differentially expressed genes are involved in binding, biological regulation, metabolic processes (MYF6 and FABP3), response to stimulus (F13A1 and CNGA3) and immune system processes (LY86, CATHL2, CCL4, and OASL), and several differentially expressed genes (e.g., ETV7, MMP9, and NOV) are involved in tumourigenesis. Eight differentially expressed genes were confirmed by quantitative reverse transcription-PCR (qRT-PCR). Based on pathway analysis, the notable signalling pathways mainly included cytokine-cytokine receptor interaction, the JAK-STAT signalling pathway and the RIG-1-like receptor signalling pathway. Conclusions The gene expression profile obtained in this study may aid a better understanding of the molecular pathogenesis of ALV-J infection in chickens. [ABSTRACT FROM AUTHOR]

Abstract: A study was initiated with the objective of evaluating the effects of sonication treatment on important quality parameters of extract of Bursa of Fabricius. Sonication of extract was done (frequency 20kHz and various amplitude levels) at 0°C for 10min, 30min, 50min, respectively. As results, the yield of bursa peptides significantly increased (p <0.05). Then we found sonicated bursa extract promoted the content of bursin and the CFU pre-B formation, exerted immunomodulatory function on antigen-specific immune responses in C57/BL6 mice immunized with inactivated Japanese encephalitis b virus (JEV) vaccine, including enhancing JEV-specific antibody and cytokine production, T-cell immunophenotyping and lymphocyte proliferation. Findings of the present study suggested the sonication treatment of Bursa of Fabricius could improve the yield as well as the quality of bursa peptides, indicating that sonication is effective in processing of bursa extract and could be a potential process for future immuno-pharmacological use. [Copyright &y& Elsevier]

Highlights: [•] Maternally derived IgA was located in chick embryo gut, bursa of Fabricius, liver and lung, but not in serum. [•] IgA was initially located at apical surface of enterocytes. [•] Towards hatch and during the post-hatch period maternally derived IgA was located in the cytoplasm of goblet cells. [•] Goblet cell IgA was shown to contain BSA-specific IgA following immunization of layers. [ABSTRACT FROM AUTHOR]

Highlights: [•] Discovery of bursal function, recognition of avian dendritic cells. [•] Secretory dendritic cells in the bursal follicle. [•] Characterization of avian follicular dendritic cells. [•] Electron micrograph of BSDC and FDC. [•] Development and differentiation route of BSDC and FDC. [Copyright &y& Elsevier]

Abstract: Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Although the effects of IBDV on bursa of Fabricius in chickens have been well reported, the impacts of IBDV on liver after IBDV infection are still unclear. In the present study, specific pathogen free (SPF) chickens were experimentally inoculated with IBDV Chinese virulent strain BC6/85, and the cells in liver and bursa were examined by immunohistochemisrty and transmission electron microscopy (TEM). The congestion of liver tissue and fatty degeneration of hepatocytes were characteristics of microscopical changes in chicken liver at 3 days post infection (d.p.i.), whereas there were follicular lymphoid necrosis, apoptosis, depletion, as well as edema and congestion in bursa. In addition, the number of IBDV-positive cells peaked at 4 d.p.i. in bursa and at 3 d.p.i. in liver, respectively. With respect to ultrastructural pathological changes of hepatocytes, mitochondria swelled and nucleus deformed into an irregular shape or its chromatin peripherally condensed which indicated that the hepatocyte was at the early stage of apoptosis, and the electron-lucent lipid droplets in a variety of sizes were observed within cytoplasm. Kupffer cells became “swollen-like” and the electron-density of their cytoplasm was lower than that of cells in uninfected group. Liver glycogen deposits significantly declined from 2 to 5 d.p.i. and recovered strongly at 6 d.p.i. More importantly, KLU01 (macrophage marker) positive (KUL01+) cells were infiltrated in bursa and liver in IBDV-exposed chickens by immunoperoxidase staining. To demonstrate the correlation between IBDV and macrophages in bursa and liver, we further investigated the colocalization of viral antigens and macrophages by double immunofluorescence labeling. At 4 d.p.i., the percentage of double positive cells (IBDV positive and KUL01+ cells) accounted for 26.5 percent of the total IBDV positive cells or 57 percent of the total KUL01+ cells in bursa. In comparison, the percentage of double positive cells in liver constituted 97 percent of the total IBDV positive cells or 99 percent of the total KUL01+ cells. These results suggest that IBDV was susceptible to KUL01+ cells in liver (mainly Kupffer cells) and replicated in the KUL01+ cells. By comparison with the influence of IBDV on bursa, our findings were the first to elucidate the pathological changes in liver after IBDV infection on a microscopical and ultrastructural scale, and, especially, to gain the initial insight into the susceptibility of Kupffer cells to IBDV. [Copyright &y& Elsevier]

Abstract: The immunopathogenesis of infectious bursal disease virus (IBDV) was investigated in different layer and broiler type chickens in comparison to highly susceptible specific-pathogen-free layers (SPF-Wh-LT) often used for experimental studies. Layer-type chickens (LT) of all genetic backgrounds showed significantly higher IBDV antigen loads in the bursa of Fabricius (BF) compared to broiler type birds (BT) (P <0.05). The variation between IBDV-infected and virus-free birds in the percentage of splenic and intrabursal B cells, T cells and macrophages differed between genetic backgrounds as well as the expression levels of cytokines. The most susceptible SPF-Wh-LT showed high levels of circulating type I IFN starting at 2days post infection (dpi) up to 7dpi coinciding with clinical IBD, while less susceptible birds showed a delayed response. Circulating cytokine levels were poorly associated neither with intrabursal nor with splenic mRNA expression of these cytokines. Detected cytokines varied in expression levels and timing between infected groups of different genetic background. These data suggest that variations in the activity of immune cell populations contribute to differences in infectious bursal disease between birds of various genetic backgrounds. [Copyright &y& Elsevier]

Abstract: The bursa of Fabricius is critical for the normal development of the B lymphocytes responsible for antibody production. However, the mechanism of the bursal-derived bioactive factor on B cell development is little reported. In this paper, chicks were immunized with BPP-II and AIV vaccine or AIV antigen, and antibody and IL-4 production were detected. The results showed that BPP-II played strongly inducing roles on the humoral immune responses. To investigate the gene expression at transcriptional level, avian pre-B lymphocyte DT40 cells were treated with BPP-II, and were analyzed with the gene microarray. The results proved that BPP-II treatment regulated 11 pathways, in which homologous recombination is a vital mechanism which is involved in antibody Ig gene conversion and diversification during B cell development. These results suggested Bursal-derived biological active factor BPP-II might be involved in the antibody production processes and B cell development, which is vital to the humoral central immune organ, the bursa of Fabricius. [Copyright &y& Elsevier]

Abstract: Toll-like receptors (TLRs) are an evolutionarily conserved group of pattern recognition receptors that play an important role in mediating host-responses to pathogens. Several TLRs have been identified in chickens and their expression has been detected in many immune cell subsets including in B cells. However, the mechanisms through which TLRs modulate B cell responses have not been well characterized in chickens. The aim of the present study was to elucidate the responses mounted by cells of the bursa of Fabricius to treatment with the TLR 3, 4 and 21 ligands, poly I:C, lipopolysaccharide (LPS) and CpG oligodeoxynucleotides (ODN), respectively. The relative expression of several immune system genes was quantified at 1, 3, 8 and 18h post-treatment. The results show that all three ligands induced the up-regulation of interferon (IFN)-γ and interleukin (IL)-10 transcripts and promoted the up-regulation of transcripts associated with antigen presentation, namely CD80 and major histocompatibility complex (MHC) class II. Furthermore, the results indicated that LPS and poly I:C induced the greatest IFN-γ and IL-10 responses, respectively, while CpG ODN was the most efficacious inducer of CD80 and MHC-II expression. Future studies may be aimed at elucidating the mechanisms of TLR-mediated activation of chicken B cells. These mechanisms may be then exploited for the development of adjuvants with enhanced ability to stimulate B cell responses. [Copyright &y& Elsevier]

Abstract: The bursa of Fabricius, the acknowledged central humoral immune organ, is vital to B cell differentiation. However, the regulatory function of the bursal-derived peptide on avian B cell proliferation has not been reported. BSP-II is a recently reported bursal-derived bioactive peptide. In this paper, 75 days-old chicks were twice subcutaneously immunized with BSP-II and inactivated avian influenza virus (AIV, H9N2 strain). It was proved that BSP-II induced a strongly AIV-specific HI antibody production in the immunized chicks. Also, BSP-II could enhance avian pre-B lymphocyte DT40 cell viability. To investigate the global patterns of gene expression in DT40 cells after BSP-II treatment, gene microarray was carried out. It was identified that the differentially expressed genes were involved in various pathways, of which six pathways were associated with signaling transductions, including ErbB signaling, MAPK signaling, Toll-like receptor signaling, Notch signaling, mTOR signaling, and Wnt signaling. Finally, RT-qPCR was used to confirm the microarray expression data. These results indicated the molecular basis of pre-B lymphocyte viability with BSP-II treatment, which provided a potential mechanism of the bursa of Fabricius on pre-B lymphocyte viability, differentiation, and development. These results are valid for the mechanism of the bursa of Fabricius on B lymphocytes development. [Copyright &y& Elsevier]

Abstract: The bursa of Fabricius (BF) is the central humoral immune organ unique to birds which plays important roles in B lymphocyte differentiation. Here, a new bursal peptide (BP11) with the amino acid sequence DVAGKLPDNRT was identified and characterized from BF. It was proved that BP11 promoted CFU pre-B formation, and regulated B cell differentiation, including increase the percentage of immature and mature B cells in BM cells co-cultured with IL-7. BP11 also exerted immunomodulatory function on antigen-specific immune responses in BALB/c mice immunized with inactivated influence virus (AIV, H9N2 subtype) vaccine, including enhancing AIV-specific antibody and cytokine production. Furthermore, it was noteworthy that BP11 stimulated antibody productions and potentiates the Th1 and Th2-type immune responses in dose-dependent manner in chicken. These results suggested that BP11 might be highly relevant for the development of avian immune system. [Copyright &y& Elsevier]

Abstract: The bursa of Fabricius (BF) is the acknowledged central immune organ, which is important to the B cell differentiation and antibody production. However, due to difficult purification, the immunomodulatory peptides from BF were little reported. In this study, the extract samples of BF were taken to a chromatographic analysis by RP-HPLC. Five novel low molecular weight peptides were isolated from BF, with amino acid sequences of YEYAY, RMYEE, GPPAT, AGCCNG, and RRL, and named as Bursal pentapeptide (BPP)-III, -IV, -V, and Bursal hexapeptide (BHP), and Bursal tripeptide (BTP), respectively. BSP-I, BSP-II, BPP-I and BPP-II are recently reported to be the bursal-derived bioactive peptides. In this paper, we analyzed the chemical formula and characteristics of these nine bursal-derived peptides. The immunization comparative experiment verified the different immunomodulatory activity of these nine bursal peptides on antibody and cytokine productions. Furthermore, the results showed that at reachable concentrations, BPP-II and BPP-I induced antibody productions, lymphocyte viabilities and cytokine responses in different dose-dependent manner in the immunized mice model, respectively. These results provided important orientations for the comprehensively understanding and study of the humoral central immune system of human, and provided a novel insight on the treatment of serious disease and immune improvement of human. [Copyright &y& Elsevier]

Antibiotics are commonly used to prevent and treat poultry microbial infections, but certain antibiotic families depress humoral immunity, such as antibody production. Poultry humoral immunity depends on the normal functioning of the bursa of Fabricius and the B lymphocytes that mature in that gland. In this study, recommended therapeutic doses of enrofloxacin, florfenicol, or ceftiofur were administered to 2-d-old chicks. On d 7 post-hatch, bursae were sampled for histological, immunohistochemical, and flow cytometric determination of Bu-1-positive (Bu-1+) cell number, percentage, and distribution. The bursa of Fabricius from all treatment and control groups had normal morphology. The administration of antibiotics significantly decreased the number of Bu-1+ cells in the bursal medulla, with a simultaneous increase of these cells in the cortex. Flow cytometry revealed a significant decrease in the percentage of bursal Bu-1+ cells from all of the studied antibiotics: enrofloxacin (93.91 ± 3.27), florfenicol (87.84 ± 7.14), and ceftiofur (89.16 ± 5.68) compared with that of the control (96.48 ± 2.60). The combination of reduced percentages of Bu-1+ cells and a decrease in these cells in the medullary region suggests lower B cell maturation. [ABSTRACT FROM AUTHOR]

Abstract: The bursa of Fabricius (BF) is acknowledged as central humoral immune organ unique to birds. Our purpose was to identify the potential function of a novel bursal-derived bioactive peptide. A bursal septpeptide (BSP-I), EPASGMM, first isolated from BF, reduced MCF and Hela tumor cells proliferation, and enhanced antitumor factor p53 luciferase activity and protein expression. Further, we found the significantly immune inducing function of BSP-I on antigen-specific immune response in BALB/c mice intraperitoneally immunized with inactivated avian influence virus (AIV, H9N2 subtype) vaccine, including of enhancing the antibody (IgG, the isotypes IgG1 and IgG2a) production, and stimulating cytokines IL-4 and IFN-γ level, and inducing T cell immunophenotyping and lymphocyte proliferation. These results suggested that as the bioactive peptide from avian humoral immune system, various biological function of BSP-I may have far-reaching implication on immune system significance, which might provide novel insight on linking between humoral immune system and development of effective immunotherapeutic strategies for treating human cancers diseases. [Copyright &y& Elsevier]

Abstract: Previous studies and field observations have suggested that genetic background influences infectious bursal disease virus (IBDV) pathogenesis. However, the influence of the virulence of the infecting IBDV strain and the mechanisms underlying the differences in susceptibility are not known. In the present study IBDV pathogenesis was compared between specific-pathogen-free layer-type (LT) chickens, which are the most susceptible chicken for IBDV and have been used as the model for pathogenesis studies, and broiler-type (BT) chickens, which are known to be less susceptible to clinical infectious bursal disease (IBD). The innate and acquired immune responses were investigated after inoculation of an intermediate (i), virulent (v) or very virulent (vv) strain of IBDV. IBDV pathogenesis was comparable among genetic backgrounds after infection with iIBDV. After infection with vIBDV and vvIBDV, LT birds showed severe clinical disease and mortality, higher bursal lesion scores and IBDV-antigen load relative to BT birds. Circulating cytokine induction varied significantly in both timing and quantity between LT and BT birds and among virus strains (P <0.05). Evaluation of different immune cell populations by flow-cytometric analysis in the bursa of Fabricius provided circumstantial evidence of a stronger local T cell response in BT birds vs. LT birds after infection with the virulent strain. On the other hand, LT birds showed a more significant increase in circulating macrophage-derived immune mediators such as total interferon (IFN) and serum nitrite than BT birds on days 2 and 3 post-vIBDV infection (P <0.05). Stronger stimulation of innate immune reactions especially after vIBDV infection in the early phase may lead to faster and more severe lesion development accompanied by clinical disease and death in LT chickens relative to BT chickens. Interestingly, no significant differences were seen between genetic backgrounds in induction of the IBDV-specific humoral response: timing of IBDV-antibody induction and antibody levels were comparable between BT and LT birds. This study clearly demonstrates a significant influence of chickens’ genetic background on disease outcome. The difference between backgrounds in IBDV susceptibility is further influenced by the virulence of the infecting virus strain. [Copyright &y& Elsevier]

Abstract: Stem cell antigen 2 (SCA2) is a Ly6 family member whose function is largely unknown. To characterize biological properties and tissue distribution of chicken SCA2, SCA2 was expressed in E. coli, purified, and a polyclonal antibody developed. Utilizing the polyclonal antibody, SCA2 is a 13kDa cell surface protein anchored by a glycosyl-phosphatidylinositol (GPI) moiety. SCA2 is expressed in connective tissues of thymus and bursa based on immunohistochemistry, immunoprecipitation, and western blots. In bursal follicles, SCA2 is specifically expressed on the cortical-medullary epithelial cells (CMEC) surrounded by MHC class II presenting cells. Expression profiles of bursal cells induced by contact with SCA2-expressing cells shows down-regulation of numerous genes including CD79B, B cell linker (BLNK), spleen tyrosine kinase (SYK), and gamma 2-phospholipase C (PLCG2) that are involved in the B cell receptor (BCR) and immune response signaling pathways. These results suggest chicken SCA2 plays a role in regulating B lymphocytes. [Copyright &y& Elsevier]

Abstract: The chicken bursa of Fabricius and calf ileal Peyer''s patch are thought to be the primary lymphoid organs of B cell development. In the bursa, the existence of secondary lymphoid tissue, called the diffusely infiltrated area, has been recognized. Recently, we have found the presence of a region of secondary lymphoid tissue in the ileal Peyer''s patch at the period of the most rapid growth of this organ. In this study, we compared the development of these secondary lymphoid tissue regions in the bursa and ileal Peyer''s patch histologically. Before hatching, lymphatic follicle formation occurred in the bursa, but not in the diffusely infiltrated area, where only a small number of lymphoid cells were found. However, during fetal calf development, lymphatic follicle formation occurred not only in the primary lymphoid organ but also in the secondary lymphoid tissue regions. Therefore, the prenatal development of the secondary lymphoid tissue regions of the bursa and ileal Peyer''s patch were distinct. After hatching, formation of the germinal center, which contained many CD4+ cells, was observed in the diffusely infiltrated area of the bursa. After birth, many CD4+ cells and IgG mRNA expression were observed in the lymphatic follicle of the secondary lymphoid tissue regions in the ileal Peyer''s patch, but rarely in the ileal Peyer''s patch lymphatic follicles. The change of character of these secondary lymphoid tissue regions at the postnatal stage might be dependent on external antigens. [Copyright &y& Elsevier]

Abstract: Recent studies here have demonstrated that increased mast cell populations and tryptase activity contribute to lesion formation in regions of immune organs in special-pathogen-free chickens after infection with very virulent infectious bursal disease virus (vvIBDV). Mast cells and their mediators have been implicated in acute inflammatory injury after vvIBDV infection, but their precise role in this process remains elusive. In this study, the role of mast cells in the vvIBDV infection process was examined using ketotifen, a mast cell membrane stabilizer. On days 1, 2, and 3 postinfection, the bursa of Fabricius (BFs) were collected to quantify mast cells, tryptase and histamine contents by cytochemistry, immunohistochemistry and fluorospectrophotometry analyses, respectively. The results showed that the mast cell populations, tryptase expression, and histamine released increased significantly in the BFs (p <0.01) of infected birds compared to controls, and acute inflammatory responses were observed in the former. In contrast, in infected chickens pretreated with ketotifen, mast cells, tryptase, and histamine were markedly decreased (p <0.01) and probably as a result, the BFs remitted significantly. The overall results suggest that mast cells are positively involved in BF injury induced by vvIBDV infection. Inhibition of mast cell degranulation and concurrent mediator release may represent a novel strategy to modulate this process. This study, thus, advances the understanding of the acute inflammatory injury mechanisms triggered by vvIBDV infection and the contribution of mast cell activity in this process. [Copyright &y& Elsevier]

Abstract: Bursa of Fabricius is a primary lymphoid organ in the birds and its microenvironment is responsible for the B cell maturation. The epithelial anlage develops through epithelial–mesenchymal interaction into which –as a third party – hemopoietic cells immigrate. Chemical bursectomy can be made by dipping or injecting eggs by testosterone solution. Both methods of treatments compromise the development of the whole embryo. Heparin beads of 70–150 µm in diameter were soaked in 5% testosterone solution and implanted into the tail bud of 4 day old chicken embryos before the bursal anlage began to develop at embryonic day 5. The locally applied testosterone inhibited the differentiation of the bursal secretory dendritic cell (BSDC) precursors, which were the inducer of the follicular epithelial bud formation. Testosterone treatment did not blocked the entering of B cells and other hemopoietic cells into the bursal mesenchyme, but in the absence of BSDC precursor cells the dendroepithelial microenvironment is not established, subsequently B cell precursors are lodged only in the bursal mesenchyme. This method is suitable for locally introducing other regulatory molecules, involved in bursal development. [Copyright &y& Elsevier]

The article "The bursa of Fabricius and antibody production" by Bruce Glick, Timothy S. Chang, and R. George Jaap first demonstrated the role of the bursa in immune development. Birds, including chickens, possess a peculiar organ, the bursa of Fabricius. The organ was recognized for more than 300 yr before its function was described in 1956. Discovery of the bursa as an essential component of the immune response began by accident. Removal of the bursa, bursectomy, during the rapid growth period diminished the antibody response to Salmonella. A paper describing this exceptional finding was initially rejected by Science and ultimately published in Poultry Science. This revelation triggered sequential events leading to the understanding of the dichotomy of the immune response. Additional work in multiple laboratories over many years revealed fundamental immune mechanisms attributable to the bursa. Understanding those mechanisms advanced agricultural and biomedical science. [ABSTRACT FROM AUTHOR]

Abstract: The structure and function of the lower intestinal tract of Rhea americana were characterized to evaluate the evolutionary relationship to other struthioniform and avian species. In 5 rheas the gross anatomy and the light and transmission electron microscopy were studied in parallel to in vitro electrophysiological measurements of ion transport. The mucosa in the colon was amplified with villi, often branched, and in the coprodeum with folds. In both tissues the epithelium was a monolayer composed of columnar absorptive cells, goblet cells and mitochondria-rich cells. Colon and coprodeum appeared to produce large amounts of mucus. The proctodeal diverticulum was rich in lymphoid tissue arranged into lobuli bursales, and it was concluded that this structure is a modified bursa of Fabricius. The sparse interlobular epithelium of the diverticulum resembled that of colon and coprodeum. Baseline short circuit currents (ISC) averaged 114.5±13.8 µA/cm2 in colon, 193.1±30.3 µA/cm2 in coprodeum and 60.4±9.1 µA/cm2 in the diverticulum. Amiloride sensitive Na+-transport amounted to 31, 88 and 38% of the baseline ISC in these three tissues, respectively. In all tissues, there was also a modest, theophylline activated chloride secretion response, and ouabain, the Na+/K+-ATPase inhibitor, abolished most of the ISC. The transepithelial resistance (TER) of the diverticulum was much higher than the other tissues. Upon dissection, urate from ureteral urine was observed in the lower third of the colon and to a lesser extent in the proctodeal diverticulum, indicating retrograde peristalsis of the urine. Thus, unlike the ostrich, there is no sphincter separating colon and coprodeum. On the other hand, a thick mucus layer was seen overlying the mucosa in both colon and coprodeum, as in the ostrich. This may help to prevent osmotic water loss, despite the presence of hyperosmotic urine (up to 800 mOsm) in the lower intestine. Both morphological and electrophysiological data from the rhea support the hypothesis that the rhea lower intestine contributes to post-renal modification of ureteral urine and to the regulation of osmotic balance, as also seen in domestic fowl and other avian species. The proctodeal diverticulum functions mainly as an immune organ, with only limited transport capability. [Copyright &y& Elsevier]

Abstract: Infectious bursal disease (IBD) is an acute and contagious viral infection of young chickens caused by IBD virus (IBDV). IBDV belongs to genus Avibirnavirus of family Birnaviridae. It is a non-enveloped virus with icosahedral symmetry that contains two segments of double-stranded RNA. The virus affects the lymphoid tissues of chickens, mainly the B cells of bursa of Fabricius, leading to severe and prolonged immunosuppression. VP2, a major structural protein of IBDV, contains antigenic epitopes responsible for induction of neutralizing/protective antibody. In the present study, VP2 gene of IBDV was cloned in a bicistronic vector along with chicken interleukin-2 (chiIL-2) as an adjuvant. An in vivo challenge study of bicistronic DNA vaccine expressing IBDV-VP2 and chicken IL-2 showed effective protection against a lethal IBD infection in chickens. In addition, mortality, gross picture of bursa and histopathological findings demonstrated the efficacy of the vaccine in reducing virulence of the disease. [Copyright &y& Elsevier]

In present study, different types of infectious bursal disease virus (IBDV), virulent strain DK01, classic strain F52/70 and vaccine strain D78 were quantified and detected in infected bursa of Fabricius (BF) and cloacal swabs using quantitative real time RT-PCR with SYBR green dye. For selection of a suitable internal control gene, real time PCR parameters were evaluated for three candidate genes, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 28S rRNA and β-actin to IBDVs. Based on this β-actin was selected as an internal control for quantification of IBDVs in BF. All BF samples with D78, DK01 or F52/70 inoculation were detected as virus positive at day 1 post inoculation (p.i.). The D78 viral load peaked at day 4 and day 8 p.i., while the DK01 and F52/70 viral load showed relatively high levels at day 2 p.i. In cloacal swabs, viruses detectable were at day 2 p.i. for DK01 and F52/70, day 8 p.i. for D78. Importantly, the primers set were specific as the D78 primer set gave no amplification of F52/70 and DK01 and the DK01 primer set gave no amplification of D78, thus DK01 and D78 could be quantified simultaneously in dually infected chickens by use of these two set of primers. The method described here is robust and may sever as a useful tool with high capacity for diagnostics as well as in viral pathogenesis studies. [ABSTRACT FROM AUTHOR]

Bursal anti-steroidogenic peptide (BASP), purified from the chicken bursa of Fabricius (BF), has been previously demonstrated to be a potent and efficacious inhibitor of steroid hormone biosynthesis from chicken ovarian, and both mammalian and avian adrenal cells in vitro. Other studies have demonstrated that BASP can markedly reduce avian and mammalian mitogen-stimulated lymphocyte proliferation. Recent studies have indicated that BASP has a structural and functional relationship with histone H1. Immunohistochemical studies using a monoclonal antibody, which is known to recognize a common histone H1 epitope from several plant and animal species identified the protein within the cytoplasm and nucleus of distinct cells within both the cortex and medulla of all BF follicles. Additionally, epithelial cells within the BF expressed the protein strongly in the cytoplasm with reduced nuclear staining. In contrast, the same antibody did not recognize the protein in thymus of the same animals. The differential expression of histone H1 immunoreactivity within selected cells of the BF may support a previous proposed role of histone H1 in extranuclear and extracellular signaling in chickens and possibly other species. [Copyright &y& Elsevier]

B lymphocyte development can occur in a variety of anatomical sites. While typically considered to be a process that occurs in the bone marrow throughout life, it is becoming clear that gut associates sites of B cell development are critically important in many species of veterinary importance. Among these sites, the bursa of Fabricius in chickens and the ileal Peyer’s patches of sheep are among the best studied. In these organs, it has become clear that many of the properties associated with B cell development in rodent and primate bone marrow do not apply. Thus while bone marrow B cell development typically involves an ongoing maturation of mature B cells from immature B lineage precursors that lack the expression of a surface immunoglobulin complex, gut associated lymphoid tissues (GALTs) may be colonized by a single wave of precursor cells during embryo development. Nonetheless, molecular analysis of the requirements for B lymphocyte development in GALTs reveals some striking parallels with requirements identified for B cell development in bone marrow. This article will discuss differences between B cell development in the bone marrow and GALTs and recent evidence emerging that yields insights into how these processes are regulated. [Copyright &y& Elsevier]

The immunocytochemical study of the K-1 monoclonal antibody indicates that the epithelial components of the bursa of Fabricius of the chicken and guinea fowl express the K-1 positive molecule. During embryogenesis, the K-1 antigen expression appears together with the bud-formation. As the number of B cells increases in the developing follicle, the K-1 expression gradually diminishes in the medullary reticular epithelial cells and completely ceases by hatching, which suggests that the molecule is developmentally regulated. After hatching, the expression of the molecule is restricted to the sealing off zone of the lymphoepithelial or medullary region of the follicle: i.e. to the cortico-medullary (CM) epithelial cells and the follicle associated epithelium (FAE) supporting cells in guinea fowl and to the latter ones in the chicken. The expression of the K-1 antigen by these epithelial components may support their structural identity. After hatching, the K-1 molecule is restricted to the CM epithelial cells and/or FAE supporting cells, which suggests that the function of the embryonic epithelial bud is taken over by the CM epithelial cells. The K-1 positive CM epithelial cells form arches, which encompass blast-like cells. The possible relationship of the CM epithelial cells and blast-like cells, which may represent the precursors of bursal secretory dendritic cells is discussed. [Copyright &y& Elsevier]

Information about several papers discussed at the symposium "Landmark Contribution from the First 100 Years of Poultry Science" in Niagara Falls, Ontario is presented. Topics include the feeding of sulfaquinoxaline to control coccidiosis in poultry, the role of bursa of Fabricius in antibody production, and effect of sulfamethazine feeding on Single Comb White Leghorn Cockerels' thyroids, combs, and testes. The symposium featured H. David Chapman, Robert L. Taylor Jr., and Wayne J. Kuenzel.