Effect of Intermediate Plus Vaccine and vvIBDV on Bursa Secretory Cells and Their Glycoprotein Production

Abstract

There are two types of secretory cells in the chicken bursa of Fabricius (BF): (a) interfollicular epithelial cells (IFE), and (b) bursal secretory dendritic cells (BSDC) in the medulla of bursal follicles. Both cells produce secretory granules, and the cells are highly susceptible to IBDV vaccination and infection. Before and during embryonic follicular bud formation, an electron-dense, scarlet-acid fuchsin positive substance emerges in the bursal lumen, the role of which is unknown. In IFE cells, IBDV infection may induce rapid granular discharge, and in several cells, peculiar granule formation, which suggests that the glycosylation of protein is injured in the Golgi complex. In control birds, the discharged BSDC granules appear in membrane-bound and subsequently solubilized, fine-flocculated forms. The solubilized, fine-flocculated substance is Movat-positive and can be a component of the medullary microenvironment, which prevents the medullary B lymphocytes from nascent apoptosis. Vaccination interferes with the solubilization of the membrane-bound substance, resulting in: (i) aggregation of a secreted substance around the BSDC, and (ii) solid lumps in the depleted medulla. The non-solubilized substance is possibly not “available” for B lymphocytes, resulting in apoptosis and immunosuppression. In IBDV infection, one part of the Movat-positive Mals fuse together to form a medullary, gp-containing “cyst”. The other part of Mals migrate into the cortex, recruiting granulocytes and initiating inflammation. During recovery the Movat-positive substance appears as solid, extracellular lumps between the cells of FAE and Mals. Possibly the Mals and Movat-positive extracellular lumps glide into the bursal lumen via FAE to eliminate cell detritus from the medulla.

Life cycle of chicken bursal secretory dendritic cell (BSDC)

“…The tumor-associated antigen MUC1+/+ is expressed by dendritic cells in synovial fluid of patients with arthritis, but not by healthy thymic or tonsillar dendritic cells ( Cloosen et al, 2004 ). Mouse dendritic cells produce mucin-like glycoprotein ( Williams et al, 2010 ) and we have recently reported glycoprotein secretion by the chicken BSDC ( Felföldi et al, 2021 ; Oláh et al, 2022 , 2023 ), which suggests some general features for the warm-blooded vertebrates (birds and mammals).…”

“…During the last 45 yr, we have published numerous papers about the structure ( Olah and Glick, 1987 ), characterization ( Olah et al, 1992 ; Olah and Glick, 1992 ; Pharr et al, 1995 ; Oláh and Nagy, 2013 ; Nagy et al, 2016 ), changes in the experimental condition ( Olah and Glick, 1978b , 1986 ; Olah et al, 1979 ), glycoprotein production ( Felföldi et al, 2021 ; Oláh et al, 2022 ) and effect of IBDV infection ( Felföldi et al, 2022 ; Oláh et al, 2023 ) of the BSDC.…”