Search for a Virus

Scientists are sure that infantile paralysis is caused by a virus. They have long known where to look for it—in the brain and spinal cord. But isolation of the elusive virus itself has led researchers on one of the most expensive searches in medical history. Last week two Stanford University scientists, backed by the National Foundation for Infantile Paralysis, thought they had finally come near the end of the trail.

Stanford Chemists Hubert S. Loring and C. E. Schwerdt had pondered a strange puzzle. Like other polio virus hunters, they had ground up and sifted the brains and spinal cords of nobody knows how many infected rats and monkeys. They had prepared virulent extracts, capable of transmitting the disease. But when they refined their material further, its virulence somehow disappeared.

Did the refining process kill the virus? Loring and Schwerdt thought lowering the temperature might keep the virus alive. As part of a long process, they made an extract from the brains and spinal cords of polio-infected cotton rats, froze it. Then, letting it start to thaw, they whirled their material in an ultra-high-speed centrifuge (60,000 revolutions per minute) to separate its protein, and with chemicals refined the protein further. Eventually they isolated a particle less than two-billionths of an inch in diameter. The protein particle proved to be 80 to 95% pure virus; a billionth of a gram of it, injected in a cotton rat, produced symptoms of polio.

Next step: to inactivate the virus (by ultraviolet radiation or chemicals) and produce a concentrated vaccine that might prevent polio.