IL-15 independent maintenance of virus-specific CD8+ T cells in the CNS during chronic infection

The role of IL-15 in T cell survival was examined during chronic CNS coronavirus infection. Similar numbers of virus-specific CD8+ T cells were retained in the CNS of IL-15−/− and wt mice, consistent with loss of IL-2/15 receptor (CD122) expression. IL-15 deficiency also had no affect on IL-7 receptor (CD127) expression, Bcl-2 upregulation, granzyme B expression, or IFN-γ secretion in CNS persisting CD8+ T cells. Furthermore, CD8+ T cell division in the CNS was reduced compared to spleen. CD8+ T cells in the persistently infected CNS are thus characterized by IL-15 independent, low level proliferation and an activated/memory phenotype.