Chronic viral infections are difficult to treat and new approaches, particularly those involving enhancing immune responses are needed. Herpes simplex virus (HSV) establishes latency, reactivates frequently, and breakthrough reactivation can occur despite suppressive antiviral therapy. Virus-specific T cells are important to control HSV, and activated T cells require increased metabolism of glutamine for their proliferation. We found that treatment of HSV-1 latently infected mice and HSV-2 infected guinea pigs with supplemental oral glutamine reduced virus reactivation. Transcriptome analysis of mice treated with glutamine showed that several interferon (IFN)- inducible genes were upregulated. Unlike wild-type mice, supplemental glutamine was ineffective in reducing the rate of HSV-1 reactivation in IFN- knock-out mice. Mice treated with glutamine had higher numbers of HSV-specific IFN- producing CD8 T cells in latently infected ganglia. Thus, glutamine may enhance the IFN--associated immune response and reduce the rate of reactivation of latent virus infection.