Very virulent infectious bursal disease virus (vvIBDV) induces immunosuppression and inflammation in young birds, which subsequently leads to high mortality. In addition, infectious bursal disease (IBD) is one of the leading causes of vaccine failure on farms. Therefore, understanding the immunopathogenesis of IBDV in both the spleen and the bursae could help effective vaccine development. However, previous studies only profiled the differential expression of a limited number of cytokines, in either the spleen or the bursae of Fabricius of IBDV-infected chickens. Thus, this study aims to evaluate the in vitro and in vivo immunoregulatory effects of vvIBDV infection on macrophage-like cells, spleen and bursae of Fabricius.
Matched MeSH terms: Bursa of Fabricius/metabolism*
Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants and chemically a class of structurally similar chemical compounds characterized by the presence of fused aromatic rings. This research was undertaken to find out immunotoxic effects produced by pyrene, phenanthrene and fluoranthene. These chemicals were injected into developing chicks at three dose levels (0.2, 2 and 20 mg per kg) through allantioc route to rule out possible mechanisms involved in immunotoxicity. DNA adduct produced by PAHs in immune organs were analyzed by DNA adduct enzyme-linked immunosorbent assay (ELISA) kit and DNA damage was assessed by comet assay. A significant increase in the DNA adduct levels was found in thymus and bursa in 2 mg and 20 mg dose levels of pyrene, fluoranthene and phenanthrene treated groups, whereas those in spleen simulated the value of controls. Comet assay indicated that PAHs especially pyrene, fluoranthene and phenanthrene were capable of inducing increased level of comet parameters in thymus at all the dose levels. Bursa of Fabricius and spleen also showed a gradual rise in comet parameters corresponding to all dose levels, but the increase was more marked as in thymus. Thus, it can be concluded that DNA adducts produced by PAHs lead to single-strand breaks and reduced DNA repair, which ultimately begin a carcinogenic process. Hence, this experiment can be considered as a strong evidence of genotoxic potential of PAHs like pyrene, phenanthrene and fluoranthene in developing chicks.
Infectious bursal disease is a highly contagious disease in the poultry industry and causes immunosuppression in chickens. Genome-wide regulations of immune response genes of inbred chickens with different genetic backgrounds, following very virulent infectious bursal disease virus (vvIBDV) infection are poorly characterized. Therefore, this study aims to analyse the bursal tissue transcriptome of six inbred chicken lines 6, 7, 15, N, O and P following infection with vvIBDV strain UK661 using strand-specific next-generation sequencing, by highlighting important genes and pathways involved in the infected chicken during peak infection at 3 days post-infection. All infected chickens succumbed to the infection without major variations among the different lines. However, based on the viral loads and bursal lesion scoring, lines P and 6 can be considered as the most susceptible lines, while lines 15 and N were regarded as the least affected lines. Transcriptome profiling of the bursa identified 4588 genes to be differentially expressed, with 2985 upregulated and 1642 downregulated genes, in which these genes were commonly or uniquely detected in all or several infected lines. Genes that were upregulated are primarily pro-inflammatory cytokines, chemokines and IFN-related. Various genes that are associated with B-cell functions and genes related to apoptosis were downregulated, together with the genes involved in p53 signalling. In conclusion, bursal transcriptome profiles of different inbred lines showed differential expressions of pro-inflammatory cytokines and chemokines, Th1 cytokines, JAK-STAT signalling genes, MAPK signalling genes, and their related pathways following vvIBDV infection.