Viral studies on human brain culture retrieved from cold storage

Tissue cultures established from brain tissues of six patients with various chronic, degenerative diseases did not show evidence of viral agents. Sucrose gradient analysis of radioactively labeled culture fluid from two patients failed to reveal the presence of any incomplete or defective virus. Extracellular fluids from three brain cultures contained a factor able to stimulate deoxyribonucleic acid synthesis of Vero cells.