| The bursa of fabricius is the main target organ of infectious bursal disease virus (IBDV) and plays an important role in body growth and the subsequent immune suppression. This study aims at analyzing the influence of IBDV infection on bursal function in the levels of genetic, molecular and cellular systematically through the replication of infectious bursal disease, detection of the gene expression profiles of bursal tissue, changes of toll-like receptors and surface molecules of mononuclear cells from bursa and peripheral blood.Four-week-old SPF chickens were infected with the standard of virulent BC6/85strains of IBDV by eye drop. And IBD was copied successfully, followed by the clinical symptoms, pathological changes of SPF chickens, as well as immunohistochemical detection of IBDV in bursa post-infected with IBDV.Microarray analysis showed that10418genes were differentially expressed, of which5421genes mainly related to inflammatory response, immune response were significantly upregulated and4998genes related to changes in cellular components and metabolism processes were significantly downregulated. Among them, expression of58genes in Toll-like receptor signaling pathway were changed, which means that they played a vital role in IBDV infection.Real-time RT-PCR was used to detect the dynamic changes in TLR3/4/15mRNA expression in bursa mononuclear cells. Results showed that the transcription levels for TLR3/15in BBMC were upregulated significantly at1dpi. The expressions of TLR3/4were upregulated significantly at5dpi. At15dpi, the levels of TLR3/4/15were rebound in PBMC. The transcription levels for TLR3/4/15in PBMC were significantly higher than those at1dpi,5dpi and15dpi, except TLR15at5dpi and15dpi.The molecules of Bu-1, CD3/4/8, CD80/86, MHC Class Ⅰ, MHC class Ⅱ were assayed by flow cytometry. In BBMC, results showed that B lymphoid cells significantly reduced while T cells and NK cells increased; MHC Class Ⅰ and MHC class Ⅱ molecules decreased at3dpi, while CD80/86increased at3dpi. In PBMC, the numbers of B lymphoid cells were significantly higher compared to control group at7dpi, other moleculars showed no significant change.In short, gene expression profiling of bursa from SPF chickens was changed after infected with IBDV. Bioinformatics analysis and the TLR3/4/15mRNA expression of bursa indicated that the toll-like receptor signaling pathway might play an important role in pathogenesis of IBDV; IBDV could reduce the numbers of B cells in the bursa of fabricius and weak the antigen-presenting function, which affect the immune response of chickens to other pathogenic, leading to immune suppression in chicken. |
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