Immunomodulation of peripheral T cells in chickens infected with Marek's disease virus: involvement in immunosuppression.
Marek's disease virus (MDV) causes T cell immunosuppression in chickens during latent infection. Morphological changes specific to apoptosis were demonstrated in peripheral blood mononuclear cells (PBMC) of MDV-infected chickens at 2-3 weeks post-inoculation (p.i.). Analysis of DNA fragmentation in T cell subsets in the peripheral blood revealed that CD4+ T cells but not CD8+ T cells underwent apoptosis after MDV infection. The proportion of CD4+ T cells, but not that of CD8+ T cells, in the peripheral blood expanded transiently at 16 days p.i., and rapidly decreased 1 week later. The decrease in CD4+ T cells might be mediated by apoptosis, because a rapid reduction in CD4+ T cells was observed when these cells underwent apoptosis. Analysis of the T cell-receptor (TCR) repertoire of the peripheral blood showed that V beta 1 but not V beta 2-alpha beta TCR-bearing cells expanded at 16 days p.i., when the transient expansion of the CD4+ T cell population was observed in these chickens. Flow cytometric profiles also showed that the expression of CD8 was down-regulated after infection with MDV, but there was no difference in the expression level of CD4 molecules between normal and infected chickens. Northern blot analysis indicated that the down-regulation of CD8 occurred at the transcriptional level. These results suggest that both apoptosis of CD4+ T cells and down-regulation of CD8 molecules could contribute to the immunosuppression caused by MDV.
Morimura
T
T
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Hattori
M
M
Ohashi
K
K
Sugimoto
C
C
Onuma
M
M
D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000276:immunology*; D016827:CD8 Antigens / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000737:chemistry / Q000166:cytology / Q000276:immunology*; D002645:Chickens / Q000276:immunology*; D015536:Down-Regulation; D008381:Herpesvirus 2, Gallid / Q000276:immunology*; D007108:Immune Tolerance; D008380:Marek Disease / Q000276:immunology*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000032:analysis; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000166:cytology / Q000276:immunology
D016827:CD8 Antigens; D012333:RNA, Messenger; D016693:Receptors, Antigen, T-Cell, alpha-beta