A host defense role for a natural antiviral substance in the nervous system.

The pathogenesis of virus infections of the nervous system (NS) is regulated by host defenses. The defensive role of a major constitutive antiviral substance was studied by determining its distribution in the human nervous system, its concentration and the ability of this viral inhibitor to protect mice against viral infection. The 4000 kDa inhibitor complex in the human nervous system was detected in brain gray and white matter, spinal cord, and sciatic nerve but not in human cerebrospinal fluid. The inhibitor was found in the extracellular medium incubated with minced murine brain. The inhibitory titer ranged from approximately 50 to 200 antiviral units per gram against polio 1, Semliki Forest, Banzi, mengo, Newcastle disease and herpes simplex 1 viruses. The inhibitor is composed of lipid and essential protein and carbohydrate moieties as determined by enzymatic inactivation. Protection of inhibitor-treated mice was demonstrated against both an alphavirus and a picornavirus. Thus a natural defensive role for the broadly antiviral inhibitor is suggested by its constitutively high concentration, wide distribution in nervous system tissues, presence in extracellular fluid and its ability to provide protection in infected mice.