Redundancy in the immune system restricts the spread of HSV-1 in the central nervous system (CNS) of C57BL/6 mice.

Resistance to lethal encephalitis in mice infected with HSV-1 via the oral mucosa is mouse strain dependent. In susceptible BALB/c, HSV-1 spreads throughout the CNS but in resistant BL/6 mice, virus is restricted to the brainstem. To examine the contribution of cellular immunity in restricting viral spread, we used a combination of antibody depleted and KO mice. Individually, NK/NKT, iNKT, CD4(+), CD8(+), and gammadelta T-cells do not restrict HSV-1 spread. In contrast, virus spreads throughout the CNS of BL/6 CL I KO mice and BL/6 mice treated with either anti-asialoGM1 Ab or both anti-CD8 and anti-NK1.1 mAbs. The results highlight the importance of redundancy in the immune system in restricting viral spread in the CNS, argue for a role of NK/NKT and CD8(+) T-cells in mediating the restriction, and provide a hierarchical order of the individual elements in controlling virus in BL/6 mice infected with HSV-1 via the oral mucosa.