Diversified bursal medullary B cells survive and expand independently after depletion following neonatal infectious bursal disease virus infection.
The primary immunoglobulin repertoire of chickens is generated not by gene rearrangement but by a subsequent process of gene conversion in proliferating immature B cells within the follicles of a specialized gut-associated lymphoid organ, the bursa of Fabricius. Neonatal infection with infectious bursal disease virus can eliminate almost the entire bursal B-cell compartment. Thereafter, two types of follicle reappear. Larger follicles, with rapidly proliferating B cells and normal structure, are correlated with partial recovery of antibody response. Smaller follicles, lacking distinct cortex and medulla, appear unable to produce antigen-responsive B cells. To understand the genesis of the two types of follicle, we analysed their VL sequences and activation-induced deaminase mRNA levels. The results provide a model of bursal repopulation in which surviving bursal stem cells generate new follicles with normal morphology and function, while surviving medullary B cells continue to proliferate slowly, under the influence of stromal cells, giving rise to the smaller follicles. The latter remain fixed in a stage of development incapable of further gene diversification.
Institute for Animal Health, Compton, UK.
David R
DR
Withers
T Fred
TF
Davison
John R
JR
Young
D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology* / Q000473:pathology; D018175:Birnaviridae Infections / Q000276:immunology* / Q000473:pathology; D002060:Bursa of Fabricius / Q000276:immunology* / Q000473:pathology; D002454:Cell Differentiation; D002645:Chickens; D003564:Cytidine Deaminase / Q000096:biosynthesis / Q000235:genetics; D015870:Gene Expression; D007147:Immunoglobulin Light Chains / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000276:immunology; D007243:Infectious bursal disease virus; D038041:Lymphopoiesis / Q000276:immunology; D011201:Poultry Diseases / Q000276:immunology* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D013234:Stem Cells / Q000276:immunology; D000098830:AICDA (Activation-Induced Cytidine Deaminase)
D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D000098830:AICDA (Activation-Induced Cytidine Deaminase); D003564:Cytidine Deaminase