VERTEBRATE BRAINS CONTAIN A BROADLY ACTIVE ANTIVIRAL SUBSTANCE

Brain tissue extracts from vertebrates were examined for non-specific, broad-spectrum virus inhibitors, previously identified and characteri zed from other body tissues and fluids. An antiviral activity found in human, bovine, ovine, porcine, lapine, murine and piscine brain tissu es shares some properties with a contact blocking-virus inhibitor, whi ch was previously found only in cell culture supernatants. The inhibit or was active against (in order of sensitivity to inhibitor) Banzi, Si ndbis, Bunyamwera, Newcastle disease, herpes simplex I, Semliki forest , polio I, mengo vaccinia and vesicular stomatitis viruses. It is appr oximately 4000 kDa and possesses a complex structure containing protei n, carbohydrate and lipid moieties. The inhibitor does not directly ne utralize virus or induce an antiviral state in cells, but appears to a ct early in the replication cycle, most likely by preventing virus att achment to target cells. Its occurrence in concentrations sufficient t o reduce virus yield in cell cultures at least 30-fold may indicate a role in limiting viral infections of the central nervous system.