NKG2D Regulates Viral Load in the CNS During Acute Picornavirus Infection (43.37)

Abstract

Abstract Neurovirulent picornaviral infections are a significant health risk in developing nations. Unfortunately, the mechanisms of picornaviral clearance from the central nervous system (CNS) are less understood and therapeutic approaches are limited. We have established a mouse model of neurovirulent picornavirus infection using the Theiler’s murine encephalomyelitis virus (TMEV) which replicates during the first 12 days postinfection (dpi) primarily in the hippocampus but is cleared from the brain by 21 dpi. Intracerebral infection of TMEV triggers the early infiltration of natural killer cells (NKCs) followed by CD8+ T cells (CTLs) into the brain. We observed that both brain-infiltrating NKCs and CTLs express the NKG2D activating receptor on their surface and 50% of the the CTLs specific to the VP2121–130 viral capsid peptide also expressed NKG2D. Concomitantly, brains of infected mice expressed NKG2D ligands such as RAE-1, H-60 and MULT-1 and microglia were the cellular locus of these ligands. Importantly, systemic treatment with the NKG2D function blocking antibody CX5 resulted in a significant increase in viral load in the brain. These results suggest that activated and infected microglia stimulate NKCs and CTLs via NKG2D in a manner that restricts viral replication. NKG2D may thus serve as a potential therapeutic target to enhance viral clearance responses during CNS infection. This work was supported by a grant from the National MS Society and by Donald and Frances Herdrich.