Recurrence of persistent virus infections causes major health problems for AIDS patients and others who are severely immunosuppressed. This is particularly true for the herpesvirus family, several members of which are present in a latent form in the majority of the population. The two human gammaherpesviruses, the Epstein- Barr virus and Human Herpesvirus-8 both cause malignancies in the immunosuppressed, including non- Hodgkin's lymphoma, central nervous system lymphomas, Kaposi's sarcoma and primary effusion lymphomas. However in healthy patients, the T cell response controls latent gammaherpesvirus infection very efficiently. Currently it is not fully understood what components of the T cell response need to be lacking in order for gammaherpesviruses to break through and cause disease. Nor is it known whether immune therapies can be developed which can restore immune surveillance and prevent virus-associated disease. In this application we study murine gammaherpesvirus (MHV-68) infection, an accepted and valuable small animal model for gammaherpesvirus pathogenesis and immunology. While normal mice control latent infection with MHV-68, spontaneous virus reactivation occurs in mice that are deficient in CD4 T cells. Virus reactivation in the absence of CD4 T cells therefore provides a model similar to recurrent gammaherpesvirus- associated disease that occurs in AIDS patients, who also lack CD4 T cells. Our research, and that of other labs, has shown that MHV-68-specific CD8 T cells are still present in the absence of CD4 T cells, and are ostensibly functional, but nevertheless unable to contain virus replication. In the preliminary data for this application we describe a factor that exerts a negative influence on the antiviral T cell response, thereby allowing virus reactivation to occur.
In Specific Aim 1 we determine the mechanism responsible for this effect, and how its blockade can partly restore control over virus reactivation. Our preliminary data also describe an immunotherapy that can enhance the CD8 T cell response to overcome this negative influence, very efficiently restoring viral control, and the mechanism of action of this therapy is elucidated in Specific Aim 2. Given the success of the two immunotherapeutic approaches described in this proposal, Specific Aim 3 tests whether these two therapies can be improved by combination with a therapeutic vaccine or by co-administration of both therapies.
This Specific aim also describes the use of a newly developed model for gammaherpesvirus- associated tumor development, and tests the effectiveness of these immunotherapies in this model. In conclusion, there is a pressing need for novel therapies that can restore control of gammaherpesvirus infection in the immune suppressed. At present there are very limited treatment options, and those that are available, such as adoptive immunotherapy, are very expensive and difficult to perform outside of specialist centers. There is a good likelihood that therapies similar to those we describe will be effective in humans, and our studies provide essential information concerning their method of action.

Public Health Relevance

Gammaherpesviruses infect the majority of the human population but are well controlled by the immune response. In patients with AIDS or other immunosuppressive conditions, these viruses can re-emerge and cause serious medical problems, including lymphomas. This application studies immunotherapies that can prevent virus recurrence in a mouse gammaherpesvirus model.

National Institute of Health (NIH)
National Cancer Institute (NCI)
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AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
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Read-Connole, Elizabeth Lee
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Dartmouth College
Schools of Medicine
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Hu, Zhuting; Usherwood, Edward J (2014) Immune escape of ?-herpesviruses from adaptive immunity. Rev Med Virol 24:365-78
Allie, S Rameeza; Zhang, Weijun; Tsai, Ching-Yi et al. (2013) Critical role for all-trans retinoic acid for optimal effector and effector memory CD8 T cell differentiation. J Immunol 190:2178-87
Liang, Xiaozhan; Crepeau, Rebecca L; Zhang, Weijun et al. (2013) CD4 and CD8 T cells directly recognize murine gammaherpesvirus 68-immortalized cells and prevent tumor outgrowth. J Virol 87:6051-4
Tsai, Ching-Yi; Allie, S Rameeza; Zhang, Weijun et al. (2013) MicroRNA miR-155 affects antiviral effector and effector Memory CD8 T cell differentiation. J Virol 87:2348-51
Hu, Zhuting; Zhang, Weijun; Usherwood, Edward J (2013) Regulatory CD8+ T cells associated with erosion of immune surveillance in persistent virus infection suppress in vitro and have a reversible proliferative defect. J Immunol 191:312-22
Allie, S Rameeza; Zhang, Weijun; Fuse, Shinchiro et al. (2011) Programmed death 1 regulates development of central memory CD8 T cells after acute viral infection. J Immunol 186:6280-6
Molloy, Michael J; Zhang, Weijun; Usherwood, Edward J (2011) Suppressive CD8+ T cells arise in the absence of CD4 help and compromise control of persistent virus. J Immunol 186:6218-26
Fuse, Shinichiro; Tsai, Ching-Yi; Rommereim, Leah M et al. (2011) Differential requirements for CD80/86-CD28 costimulation in primary and memory CD4 T cell responses to vaccinia virus. Cell Immunol 266:130-4
Obar, Joshua J; Molloy, Michael J; Jellison, Evan R et al. (2010) CD4+ T cell regulation of CD25 expression controls development of short-lived effector CD8+ T cells in primary and secondary responses. Proc Natl Acad Sci U S A 107:193-8
Molloy, Michael; Zhang, Weijun; Usherwood, Edward (2010) Mononucleosis and antigen-driven T cell responses have different requirements for interleukin-2 signaling in murine gammaherpesvirus infection. J Virol 84:10923-7

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