CD8 super(+) T Cell Dysfunction and Increase in Murine Gammaherpesvirus Latent Viral Burden in the Absence of 4-1BB Ligand

• Published in: Journal of Immunology 2007-04, Vol.178 (8), p.5227-5236
• Main Authors: Fuse, Shinichiro, Bellfy, Sarah, Yagita, Hideo, Usherwood, Edward J
• Format: Article
• Language: English
• Subjects: Gammaherpesvirus; Murine gammaherpesvirus
• ISSN: 0022-1767; 1365-2567

Studies of costimulatory receptors belonging to the TNFR family have revealed their diverse roles in affecting different stages of the T cell response. The 4-1BB ligand (4-1BBL)/4-1BB pathway has emerged as a receptor-ligand pair that impacts not the initial priming, but later phases of the T cell response, such as sustaining clonal expansion and survival, maintaining memory CD8 super(+) T cells, and supporting secondary expansion upon Ag challenge. Although the role of this costimulatory pathway in CD8 super(+) T cell responses to acute viral infections has been well-studied, its role in controlling chronic viral infections in vivo is not known to date. Using the murine gammaherpesvirus-68 (MHV-68) model, we show that 4-1BBL-deficient mice lack control of MHV-68 during latency and show significantly increased latent viral loads. In contrast to acute influenza infection, the numbers of MHV-68-specific memory CD8 super(+) T cells were maintained during latency. However, the virus-specific CD8 super(+) T cells showed defects in function, including decreased cytolytic function and impaired secondary expansion. Thus, 4-1BBL deficiency significantly affects the function, but not the number, of virus-specific CD8 super(+) T cells during gammaherpesvirus latency, and its absence results in an increased viral burden. Our study suggests that the 4-1BB costimulatory pathway plays an important role in controlling chronic viral infections.