title: CD8+ T cells mediate recovery and immunopathology in West Nile virus encephalitis.
abstract: C57BL/6J mice infected intravenously with the Sarafend strain of West Nile virus (WNV) develop a characteristic central nervous system (CNS) disease, including an acute inflammatory reaction. Dose response studies indicate two distinct kinetics of mortality. At high doses of infection (10(8) PFU), direct infection of the brain occurred within 24 h, resulting in 100% mortality with a 6-day mean survival time (MST), and there was minimal destruction of neural tissue. A low dose (10(3) PFU) of infection resulted in 27% mortality (MST, 11 days), and virus could be detected in the CNS 7 days postinfection (p.i.). Virus was present in the hypogastric lymph nodes and spleens at days 4 to 7 p.i. Histology of the brains revealed neuronal degeneration and inflammation within leptomeninges and brain parenchyma. Inflammatory cell infiltration was detectable in brains from day 4 p.i. onward in the high-dose group and from day 7 p.i. in the low-dose group, with the severity of infiltration increasing over time. The cellular infiltrates in brain consisted predominantly of CD8(+), but not CD4(+), T cells. CD8(+) T cells in the brain and the spleen expressed the activation markers CD69 early and expressed CD25 at later time points. CD8(+) T-cell-deficient mice infected with 10(3) PFU of WNV showed increased mortalities but prolonged MST and early infection of the CNS compared to wild-type mice. Using high doses of virus in CD8-deficient mice leads to increased survival. These results provide evidence that CD8(+) T cells are involved in both recovery and immunopathology in WNV infection.
authors.affiliation: Division of Immunology and Genetics, The John Curtin School of Medical Research, The Australian National University, Canberra ACT 2601, Australia.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Mario
authors.initials: M
authors.lastname: Lobigs
authors.forename: Eva
authors.initials: E
authors.lastname: Lee
authors.forename: Arno
authors.initials: A
authors.lastname: Müllbacher
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018450:Disease Progression; D018792:Encephalitis, Viral / Q000276:immunology* / Q000401:mortality / Q000473:pathology* / Q000821:virology; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013154:Spleen / Q000166:cytology / Q000276:immunology; D014779:Virus Replication; D014901:West Nile Fever / Q000276:immunology / Q000401:mortality / Q000473:pathology / Q000821:virology; D014902:West Nile virus / Q000276:immunology / Q000472:pathogenicity* / Q000502:physiology