IL-12 PROMOTES ENHANCED RECOVERY FROM VESICULAR STOMATITIS-VIRUS INFECTION OF THE CENTRAL-NERVOUS-SYSTEM

To investigate the role of a cytokine in host defense against the vesi cular stomatitis virus (VSV) infection of the central nervous system ( CNS), IL-12 was injected i,p, into groups of 10 BALB/c mice on days -1 , 0, 1, 2, and 3 postinfection, Four days postinfection, mice were exa mined. IL-12 strongly enhanced immunity to VSV infection in the CNS as demonstrated by i) decreased VSV titers in brain homogenate of IL-12- injected mice compared with those of controls; 2) increased expression of inducible nitric oxide synthase in the CNS; 3) enhanced expression of both MHC class I and class II Ags in the CNS; 4) increased T cell infiltration in the CNS, especially in the olfactory bulb; and 5) dimi nished VSV-induced apoptosis in olfactory bulb, No detrimental effect was observed even with the 200 ng/mouse dose of IL-12, Protective effe cts of IL-12 were dose dependent, Collectively, these results demonstr ate that exogenously added IL-12, even when injected peripherally, sig nificantly enhances recovery from VSV infection of the CNS.