CXCL10/CXCR3-Dependent Mobilization of Herpes Simplex Virus-Specific CD8 T and CD8 T Cells within Infected Tissues Allows Efficient Protection against Recurrent Herpesvirus Infection and Disease.

Herpes simplex virus 1 (HSV-1) establishes latency within the sensory neurons of the trigeminal ganglia (TG). HSV-specific memory CD8 T cells play a critical role in preventing HSV-1 reactivation from TG and subsequent virus shedding in tears that trigger recurrent corneal herpetic disease. The CXC chemokine ligand 10 (CXCL10)/CXC chemokine receptor 3 (CXCR3) chemokine pathway promotes T cell immunity to many viral pathogens, but its importance in CD8 T cell immunity to recurrent herpes has been poorly elucidated. In this study, we determined how the CXCL10/CXCR3 pathway affects TG- and cornea-resident CD8 T cell responses to recurrent ocular herpesvirus infection and disease using a well-established murine model in which HSV-1 reactivation was induced from latently infected TG by UV-B light. Following UV-B-induced HSV-1 reactivation, a significant increase in both the number and function of HSV-specific CXCR3 CD8 T cells was detected in TG and corneas of protected C57BL/6 (B6) mice, but not in TG and corneas of nonprotected CXCL10 or CXCR3 deficient mice. This increase was associated with a significant reduction in both virus shedding and recurrent corneal herpetic disease. Furthermore, delivery of exogenous CXCL10 chemokine in TG of CXCL10 mice, using the neurotropic adeno-associated virus type 8 (AAV8) vector, boosted the number and function of effector memory CD8 T cells (T) and tissue-resident memory CD8 T cells (T), but not of central memory CD8 T cells (T), locally within TG, and improved protection against recurrent herpesvirus infection and disease in CXCL10 deficient mice. These findings demonstrate that the CXCL10/CXCR3 chemokine pathway is critical in shaping CD8 T cell immunity, locally within latently infected tissues, which protects against recurrent herpesvirus infection and disease. We determined how the CXCL10/CXCR3 pathway affects CD8 T cell responses to recurrent ocular herpesvirus infection and disease. Using a well-established murine model, in which HSV-1 reactivation in latently infected trigeminal ganglia was induced by UV-B light, we demonstrated that lack of either CXCL10 chemokine or its CXCR3 receptor compromised the mobilization of functional CD8 T and CD8 T cells within latently infected trigeminal ganglia following virus reactivation. This lack of T cell mobilization was associated with an increase in recurrent ocular herpesvirus infection and disease. Inversely, augmenting the amount of CXCL10 in trigeminal ganglia of latently infected CXCL10-deficient mice significantly restored the number of local antiviral CD8 T and CD8 T cells associated with protection against recurrent ocular herpes. Based on these findings, a novel "prime/pull" therapeutic ocular herpes vaccine strategy is proposed and discussed.