Coming Soon: Safer Blood

By John Langone

Many people who get blood transfusions these days are understandably nervous. Transfusions have saved countless lives, but they have sometimes transmitted serious blood-borne diseases, including AIDS. While public health officials point out that careful testing has all but eradicated the AIDS virus from the blood supply, they have not been able to claim that transfusions are perfectly safe. Reason: about 5% of patients who receive transfusions are exposed to a virus that can cause a potentially deadly liver infection called non-A, non-B hepatitis.

The mysterious malady is so named because it is not caused by the widely recognized A and B strains of hepatitis viruses. Symptoms include fever, nausea and fatigue and, in chronic cases, cirrhosis of the liver. About 5% of the U.S. population harbors non-A, non-B viruses. The majority of those who are exposed show no symptoms, but of the patients who come down with chronic liver disease, an estimated 10% die within five years. About 150,000 new infections occur each year because of blood transfusions.

This last major threat in the U.S. blood supply may soon be greatly reduced. After six years of research, scientists at Chiron, a genetic-engineering firm in Emeryville, Calif., have developed a test for the presence of a non-A, non- B hepatitis virus in blood samples. According to papers published last week in the journal Science, trials have shown that Chiron's test is highly reliable. It can now help eliminate the virus from the blood supply. The inexpensive test (about $2 per blood sample) is expected to be approved by the Food and Drug Administration this year and marketed early in 1990 by Chiron and Ortho Diagnostics Systems, a subsidiary of Johnson & Johnson. Said Dr. S. Gerald Sandler, medical director for blood services of the American Red Cross: "This is a very significant scientific achievement that virtually closes the chapter on post-transfusion hepatitis."

Chiron's initial breakthrough was to isolate a viral protein from blood samples taken from patients with non-A, non-B hepatitis. By cloning large quantities of the protein, the company was able to develop a test to detect its presence in blood. Chiron called the pathogen the "hepatitis-C virus." In clinical studies done at the National Institutes of Health, the Centers for Disease Control and laboratories in Italy and Japan, blood samples from patients thought to have non-A, non-B hepatitis were screened using Chiron's test. At least 80% of the samples tested positive for the hepatitis-C virus.

The fact that the test did not detect non-A, non-B hepatitis 100% of the time suggests that there may be still more viruses at large that can cause hepatitis. But the A, B and C viruses seem to cause the large majority of cases, and so researchers are confident that they can now almost eliminate the risk of contracting hepatitis from a blood transfusion.

Eradicating the disease is another matter. Like the AIDS and hepatitis-B viruses, hepatitis C is spread by sexual contact and, among drug addicts, through contaminated needles. But Chiron's work offers hope that the disease can be controlled. Isolating a protein from the hepatitis-C virus has made it possible to develop a vaccine to ward off the infection. Chiron biochemist Michael Houghton cautions that hepatitis C could be "one of those awkward viruses like herpes and AIDS" for which vaccines are elusive. But, he says, the C virus resembles the one that causes German measles, which can be prevented by one of the "best vaccines ever developed." Chiron plans to test potential hepatitis-C vaccines in animals later this year.