Differential Evolution and Stability of Epitope-Specific CD8+ T Cell Responses in EBV Infection

Abstract

Murine models of lymphocytic choriomeningitis virus infection suggest that the memory CD8+ T cell repertoire is reflective of the CD8+ T cell repertoire generated during acute infection. Less is known regarding the evolution of CD8+ T cell repertoires during human viral infections. We therefore examined epitope-specific CD8+ T cell responses in a large cohort of individuals with acute through latent Epstein-Barr virus infection. Using 16 of 20 published EBV epitopes restricted by HLA-A2, HLA-A3 or HLA-B7, we showed that lytic cycle-specific CD8+ T cell responses predominated during acute EBV infection. However, whereas HLA-A2+-restricted BMLF-1-specific CD8+ T cell responses were maintained through latency, HLA-A2+- and HLA-B7+-restricted BZLF-1, as well as HLA-A3+-restricted BRLF-1 CD8+ T cell responses, were generated but not readily maintained. Analyses of CD8+ T cell responses to EBV latent cycle Ags showed delayed detection and lower frequencies of latent epitope-specific CD8+ T cell responses during acute EBV infection, with maintenance of these responses 1 yr post-EBV infection. Early BMLF-1 and EBNA-3A epitope-specific CD8+ T cell frequencies did not correlate with their frequencies at 1 yr postinfection. Interestingly, populations of EBV-specific CD8+ T cells were stable during 20 mo in our long term EBV-seropositive populations, suggesting homeostasis between virus and the host immune system. This study demonstrates that CD8+ T cell repertoires generated during persistent viral infections are not simply reflective of the initial pool of CD8+ T cells and provides evidence that the generation of CD8+ T cell responses to a persistent infection is a dynamic process.