Herpes simplex virus–1 (HSV-1) is the most common cause of sporadic viral encephalitis, which can be lethal or result in severe neurological defects even with antiviral therapy. While HSV-1 causes encephalitis in spite of HSV-1–specific humoral and cellular immunity, the mechanism by which HSV-1 evades the immune system in the central nervous system (CNS) remains unknown. Here we describe a strategy by which HSV-1 avoids immune targeting in the CNS. The HSV-1 UL13 kinase promotes evasion of HSV-1–specific CD8+ T cell accumulation in infection sites by downregulating expression of the CD8+ T cell attractant chemokine CXCL9 in the CNS of infected mice, leading to increased HSV-1 mortality due to encephalitis. Direct injection of CXCL9 into the CNS infection site enhanced HSV-1–specific CD8+ T cell accumulation, leading to marked improvements in the survival of infected mice. This previously uncharacterized strategy for HSV-1 evasion of CD8+ T cell accumulation in the CNS has important implications for understanding the pathogenesis and clinical treatment of HSV-1 encephalitis.
Naoto Koyanagi, Takahiko Imai, Keiko Shindo, Ayuko Sato, Wataru Fujii, Takeshi Ichinohe, Naoki Takemura, Shigeru Kakuta, Satoshi Uematsu, Hiroshi Kiyono, Yuhei Maruzuru, Jun Arii, Akihisa Kato, Yasushi Kawaguchi
Effect of direct injection of CXCL9 into the brain stems of mice ocularly infected with UL13R on CD8+ T cell accumulation and viral pathogenicity.