Transition from acute to persistent infection: Antigen persistence and cytotoxic T cells response in infectious bursal disease virus infected SPF chickens (P6129)

Abstract

Abstract Described by Cosgrove about a half century ago, infectious bursal disease (IBD) is as an acute, highly contagious viral infection of young chickens, which last for 7 to 10 days and leads to immunosuppression. Here, we are reporting for the first time that in IBD virus (IBDV) -infected, specific pathogen free (SPF) chickens bursa, the virus antigen, macrophages, CD4+, CD8+ cells, Fas, Fas ligand (FasL), and caspase-3 were consistently detected by immunohistochemistry up to 56 days post inoculation (DPI). Two-week-old SPF chickens were inoculated intraocularly with standard challenge strain (STC) using a 104embryo infectious dose. Histopathology of bursal tissues revealed severe lymphoid follicular depletion at DPI 5-28. A distinctive pattern of bursal follicles in the form of small and large follicles was detected from DPI 35 to 56. At 42 and 56 DPI a characteristic clustered pattern of IBDV antigen, macrophages, CD4+, CD8+ cells, Fas, FasL, and caspase-3 were detected in or around the small bursal follicles as compared to large bursal follicles. This is the first report on the persistence of IBDV antigen causing a latent infection, in bursal tissues of SPF chicken. Detection of persistent IBDV infection is highly significant in the elucidation of virus pathogenesis, immunology and epidemiology and it raises many questions that need to be answered in future studies.