NEW procedure may add important safeguard to nation's blood supply

<br>SAN FRANCISCO (AP) _ A key part of the nation's blood supply could be made safe from viruses, bacteria and parasites with the use of a chemical activated by ultraviolet light, a biotech company

Monday, June 4th 2001, 12:00 am

By: News On 6

SAN FRANCISCO (AP) _ A key part of the nation's blood supply could be made safe from viruses, bacteria and parasites with the use of a chemical activated by ultraviolet light, a biotech company said Monday.

Cerus Corp. said it has performed hundreds of successful tests on blood products using a process it calls Helinx, which attacks strands of genetic material at the center of all living things and prevents DNA and RNA from replicating.

The process doesn't work with red blood cells, because they are too opaque for ultraviolet light to penetrate. But it renders killer viruses and bacteria harmless in translucent platelets and plasma, Cerus said.

Dr. Bernadine Healy, national director for the American Red Cross, said the procedure could add significant protection to the blood supply.

``Obviously, we're very excited about this,'' she said. ``From the perspective of the Red Cross, we see it as a way to screen pathogens, viruses or parasites that we don't test for or don't know about.''

The Red Cross already screens for 13 viruses and pathogens in donated blood, including hepatitis, syphilis and HIV, Healy said.

What sets Helinx apart is that it attacks any viruses, known and unknown, Cerus said. It prevents replication in any cell containing genetic material; blood cells have no RNA and don't reproduce.

``Using this process we can protect the blood supply from new disease-causing organisms without having to know specifically what they are,'' said CEO Stephen Isaacs. ``So it's kind of like an umbrella for the blood supply.''

Isaacs and University of California, Berkeley, professor John Hearst, both chemists, worked with Larry Corash, a hematologist, for about a decade to develop the procedure.

A light-activated photochemical is added to plasma and platelets that have been separated from red blood cells. The chemical mixes with any genetic material, and when exposed to ultraviolet light, forms a permanent bond with DNA and RNA, preventing the strands from replicating.

Viruses and bacteria that can't reproduce do little harm.

The side effects of the chemical _ called psoralen _ are not yet clearly known, Healy said, and the process has yet to receive Food and Drug Administration approval.

She estimated the cost at $70 to $80 a unit of blood product: ``But if that's the price we pay for a safer unit of blood, I believe it is our obligation to do that.''

White blood cells, where viruses and bacteria sometimes lurk, are also inactivated by the procedure. The Red Cross currently uses a process called leukoreduction to rid blood products of white blood cells. This alone costs $30 a unit, Healy said.

``To make platelets and plasma pathogen-free is a big step,'' but it's important to note that the ultraviolet-light procedure cannot be used on red blood cells, Healy said.

And red blood cells account for the greatest number of transfusions in the United States _ about 13 million a year, said Scott Murphy, senior medical scientist with the Red Cross' Pennsylvania-New Jersey region. Platelets account for only about 2 million transfusions a year.

Isaacs said studies show treated blood products work as well as non-treated. Clinical trials on platelets are complete and trials for plasma are nearly complete, he said.

Isaacs predicted treated platelet products will be on the European market early next year and the U.S. market at the end of next year. Plasma should be on the market by 2003.

Healy noted that the method will not neutralize the human form of mad cow disease, which contains pure proteins without DNA or RNA.

Even if new methods are approved, the Red Cross will continue to use many other safeguards to prevent infected blood from entering the supply, she said.

``There's no one magic bullet. We'll still be testing our blood for major pathogens.''