Absence of cross-presenting cells in the salivary gland and viral immune evasion confine cytomegalovirus immune control to effector CD4 T cells

Horizontal transmission of cytomegaloviruses (cmv) occurs via prolonged excretion from mucosal surfaces. we used murine cmv (mcmv) infection to investigate the mechanisms of immune control in secretory organs. cd4 t cells were crucial to cease mcmv replication in the salivary gland (sg) via direct secretion of ifnγ that initiated antiviral signaling on non-hematopoietic cells. in contrast,cd4 t cell helper functions for cd8 t cells or b cells were dispensable. despite sg-resident mcmv-specific cd8 t cells being able to produce ifnγ,the absence of mhc class i molecules on infected acinar glandular epithelial cells due to viral immune evasion,and the paucity of cross-presenting antigen presenting cells (apcs) prevented their local activation. thus,local activation of mcmv-specific t cells is confined to the cd4 subset due to exclusive presentation of mcmv-derived antigens by mhc class ii molecules on bystander apcs,resulting in ifnγ secretion interfering with viral replication in cells of non-hematopoietic origin. © 2011 walton et al.