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* Center for Vaccines and Immunity, Columbus Childrens Research Institute, Columbus, OH 43205; and
College of Medicine, The Ohio State University, Columbus, OH 43210
During infection with viruses that establish latency, the immune system needs to maintain lifelong control of the infectious agent in the presence of persistent Ag. By using a
-herpesvirus (
HV) infection model, we demonstrate that a small number of virus-specific central-memory CD8+ T cells develop early during infection, and that virus-specific CD8+ T cells maintain functional and protective capacities during chronic infection despite low-level Ag persistence. During the primary immune response, we show generation of CD8+ memory T cell precursors expressing lymphoid homing molecules (CCR7, L-selectin) and homeostatic cytokine receptors (IL-7
, IL-2/IL-15
). During long-term persistent infection, central-memory cells constitute 2050% of the virus-specific CD8+ T cell population and maintain the expression of L-selectin, CCR7, and IL-7R molecules. Functional analyses demonstrate that during viral persistence: 1) CD8+ T cells maintain TCR affinity for peptide/MHC complexes, 2) the functional avidity of CD8+ T cells measured as the capacity to produce IFN-
is preserved intact, and 3) virus-specific CD8+ T cells have in vivo killing capacity. Next, we demonstrate that at 8 mo post-virus inoculation, long-term CD8+ T cells are capable of mediating a protective recall response against the establishment of
HV68 splenic latency. These observations provide evidence that functional CD8+ memory T cells can be generated and maintained during low-load
HV68 persistence.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported in part by National Institutes of Health Grant AI-59603 and by Columbus Childrens Research Institute.
2 Address correspondence and reprint requests to Dr. Emilio Flaño, Center for Vaccines and Immunity, Columbus Childrens Research Institute, Columbus, OH 43205. E-mail address: flanoe{at}ccri.net
3 Abbreviations used in this paper: LCMV, lymphocytic choriomeningitis virus;
HV68, murine
-herpesvirus 68; LDA-PCR, limiting dilution nested PCR; RT, room temperature; d.p.i., days postinfection; m.p.i., months postinfection; MLN, mediastinal lymph node.
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