Early pathogenesis during infectious bursal disease in susceptible chickens is associated with changes in B cell genomic methylation and loss of genome integrity

Dynamic alterations in T-lymphocyte subsets assessed by flow cytometry in chickens following exposure to infectious bursal disease virus: A systematic review

Infectious bursal disease virus (IBDV) is a significant pathogen in poultry, causing acute immunosuppressive disease in young chickens. While B-lymphocyte involvement in IBDV pathogenesis is known, the role of T-cells is incompletely understood. This systematic review presents the alterations in chicken T-lymphocyte subsets after IBDV exposure, assessed by flow cytometry analysis. Four databases were queried for identifying eligible studies focused on experimental infections measuring T-lymphocyte changes in the bursa of Fabricius, spleen, thymus, and peripheral blood mononuclear cells. Of 488 studies found, 25 met the pre-established criteria and were included in the qualitative synthesis of results. Most studies analysed T-lymphocyte responses during the acute phase of IBDV infection, primarily focusing on CD4+ and CD8+ T-cells. Other subsets, such as γδ T-cells and double-positive CD4+CD8+ T-cells, were less frequently investigated. An increase in T-lymphocytes was noted in the bursa of Fabricius, suggesting their active role in viral clearance. In the spleen, CD4+ T-cells commonly increased, while CD8+ responses varied among studies. Increased levels in T-cells were also noted during the chronic infection in the bursa of Fabricius, possibly due to persistent viral antigens. Overall, variations in flow cytometry methods and T-cell output reporting were noted among studies. Based on the data collected, further investigation into diverse T-cell subpopulations beyond CD4+ and CD8+ is needed, as well as the standardization of flow cytometry assays in chickens.

Unravelling the impact of epigenetic mechanisms on offspring growth, production, reproduction and disease susceptibility

Epigenetic mechanisms, such as DNA methylation, histone modifications and non-coding RNA molecules, play a critical role in gene expression and regulation in livestock species, influencing development, reproduction and disease resistance. DNA methylation patterns silence gene expression by blocking transcription factor binding, while histone modifications alter chromatin structure and affect DNA accessibility. Livestock-specific histone modifications contribute to gene expression and genome stability. Non-coding RNAs, including miRNAs, piRNAs, siRNAs, snoRNAs, lncRNAs and circRNAs, regulate gene expression post-transcriptionally. Transgenerational epigenetic inheritance occurs in livestock, with environmental factors impacting epigenetic modifications and phenotypic traits across generations. Epigenetic regulation revealed significant effect on gene expression profiling that can be exploited for various targeted traits like muscle hypertrophy, puberty onset, growth, metabolism, disease resistance and milk production in livestock and poultry breeds. Epigenetic regulation of imprinted genes affects cattle growth and metabolism while epigenetic modifications play a role in disease resistance and mastitis in dairy cattle, as well as milk protein gene regulation during lactation. Nutri-epigenomics research also reveals the influence of maternal nutrition on offspring's epigenetic regulation of metabolic homeostasis in cattle, sheep, goat and poultry. Integrating cyto-genomics approaches enhances understanding of epigenetic mechanisms in livestock breeding, providing insights into chromosomal structure, rearrangements and their impact on gene regulation and phenotypic traits. This review presents potential research areas to enhance production potential and deepen our understanding of epigenetic changes in livestock, offering opportunities for genetic improvement, reproductive management, disease control and milk production in diverse livestock species.

Infectious bursal disease virus replication is inhibited by avain T cell chemoattractant chemokine CCL19

Chemokine CCL19, together with its receptor CCR7, is one of the most important factors recruiting immune cells into target organ during virus infection. Our previous study has shown that CCL19 played a vital role in the process of T cell trafficking into bursae during bursal disease virus (IBDV) infection. In this study, we hypothesized that CCL19 could exert direct influences on IBDV replication other than recruiting immune cells. A eukaryotic expression vector of pEGFP-N1/CCL19 was successfully constructed and identified by PCR, double enzymes digestion, and sequencing. Different concentrations of pEGFP-N1/CCL19 plasmids were transfected into DF1 cells and CCL19 protein was highly expressed. Then, DF1 cells were infected with IBDV B87 strain post-transfection. Based on PCR and Western blot results, CCL19 could obviously decrease the gene levels of VP1 and VP2 and the protein levels of VP2 and VP3. When CCL19 was knocked down, the gene levels of VP1 and VP2 were significantly upregulated. Moreover, indirect immunostaining revealed that the IBDV content was largely decreased after CCL19 overexpression. Additionally, CCL19 inhibitory effects might rely on activation of the JNK signal pathway. Taken together, chemokine CCL19 directly blocks IBDV replication in DF1 cells, indicating that CCL19 could play crucial functions other than recruiting T cells during the pathogenesis of IBDV.

Infectious bursal disease virus' interferences with host immune cells: What do we know?

AbstractInfectious bursal disease virus (IBDV) induces one of the most important immunosuppressive diseases in chickens leading to high economic losses due increased mortality and condemnation rates, secondary infections and the need for antibiotic treatment. Over 400 publications have been listed in PubMed.gov in the last five years pointing out the research interest in this disease and the development of improved preventive measures. While B cells are the main target cells of the virus, also other immune and non-immune cell populations are affected leading a multifaceted impact on the normally well orchestrated immune system in IBDV-infected birds. Recent studies clearly revealed the contribution of innate immune cells as well as T cells to a cytokine storm and subsequent death of affected birds in the acute phase of the disease. Transcriptomics identified differential regulation of immune related genes between different chicken genotypes as well as virus strains, which may be associated with a variable disease outcome. The recent availability of primary B cell culture systems allowed a closer look into virus-host interactions during IBDV-infection. The new emerging field of research with transgenic chickens will open up new opportunities to understand the impact of IBDV on the host also under in vivo conditions, which will help to understand the complex virus-host interactions further.

Folic acid enhances proinflammatory and antiviral molecular pathways in chicken B-lymphocytes infected with a mild infectious bursal disease virus

1. This study evaluated the effect of folic acid (FA) supplementation on the proinflammatory and antiviral molecular pathways of B-lymphocytes infected with a modified live IBDV (ST-12) mild vaccine strain during a timed post-infection analysis.2. A chicken B-lymphocytes (DT-40) cell line was cultured in triplicate at a concentration of 5 × 10⁵ cells per well in 24-well plates; and was divided into three groups: 1: No virus, FA; 2: Virus, no FA; 3: Virus + FA at a concentration of 3.96 mM. The experiment was repeated three times.3. Cells in groups 2 and 3 were infected with a modified live IBDV (ST-12) mild vaccine strain at one multiplicity of infection (MOI: 1). After 1 hour of virus adsorption, samples were collected at 0, 3, 6, 12, 24 and 36 hours post-infection (hpi).4. The modified live IBDV (ST-12) mild vaccine strain triggered a B-lymphocyte specific immune response associated with the upregulation of genes involved in virus recognition (Igß), virus sensing (TLR-2, TLR-3, TLR-4 and MDA5), signal transduction and regulation (TRIF, MyD88 and IRF7), and the antiviral effector molecules (IFN-α, OAS, PKR, and viperin).5. FA supplementation modulated IBDV replication and regulated the proinflammatory and antiviral downstream molecular pathways.6. In conclusion, the low virulent pathotype serotype I modified live IBDV (ST-12) mild vaccine strain was able to trigger and mount an immune response in chicken B-lymphocytes without affecting B-cell viability. FA supplementation modulated B lymphocytes response and improved their innate immune proinflammatory and antiviral response molecular pathways.

Impacts of Epigenetic Processes on the Health and Productivity of Livestock

The dynamic changes in the epigenome resulting from the intricate interactions of genetic and environmental factors play crucial roles in individual growth and development. Numerous studies in plants, rodents, and humans have provided evidence of the regulatory roles of epigenetic processes in health and disease. There is increasing pressure to increase livestock production in light of increasing food needs of an expanding human population and environment challenges, but there is limited related epigenetic data on livestock to complement genomic information and support advances in improvement breeding and health management. This review examines the recent discoveries on epigenetic processes due to DNA methylation, histone modification, and chromatin remodeling and their impacts on health and production traits in farm animals, including bovine, swine, sheep, goat, and poultry species. Most of the reports focused on epigenome profiling at the genome-wide or specific genic regions in response to developmental processes, environmental stressors, nutrition, and disease pathogens. The bulk of available data mainly characterized the epigenetic markers in tissues/organs or in relation to traits and detection of epigenetic regulatory mechanisms underlying livestock phenotype diversity. However, available data is inadequate to support gainful exploitation of epigenetic processes for improved animal health and productivity management. Increased research effort, which is vital to elucidate how epigenetic mechanisms affect the health and productivity of livestock, is currently limited due to several factors including lack of adequate analytical tools. In this review, we (1) summarize available evidence of the impacts of epigenetic processes on livestock production and health traits, (2) discuss the application of epigenetics data in livestock production, and (3) present gaps in livestock epigenetics research. Knowledge of the epigenetic factors influencing livestock health and productivity is vital for the management and improvement of livestock productivity.

Immunomodulatory Potential of Tinospora cordifolia and CpG ODN (TLR21 Agonist) against the Very Virulent, Infectious Bursal Disease Virus in SPF Chicks

Infectious bursal disease (IBD), caused by infectious bursal disease virus (IBDV), is characterized by severe immunosuppression in young chicks of 3 to 6 week age group. Although vaccines are available to prevent IBD, outbreaks of disease are still noticed in the field among vaccinated flocks. Further, the birds surviving IBD become susceptible to secondary infections caused by various viral and bacterial agents. This study assessed the immunoprophylactic potential of Cytosine-guanosinedeoxynucleotide (CpG) oligodeoxynucleotides (ODN) and Tinospora cordifolia stem aqueous extract in the specific pathogen free (SPF) chicks, experimentally infected with very virulent IBDV (vvIBDV). Both of these agents (CpG ODN and herbal extract) showed significant increase in the IFN-γ, IL-2, IL-4, and IL-1 levels in the peripheral blood mononuclear cells (PBMCs) (p < 0.05) of chickens in the treatment groups following IBD infection.Further we found significant reduction in mortality rate in vvIBDV infected chicks treated with either, or in combination, compared with the birds of control group. Additionally, the adjuvant or immune enhancing potential of these two immunomodulatory agents with the commercially available IBDV vaccine was determined in chicks. The augmentation of vaccine response in terms of an enhanced antibody titer after vaccination, along with either or a combination of the two agents was noticed. The findings provide a way forward to counter the menace of IBDV in the poultry sector through use of these herbal or synthetic immunomodulatory supplements.