Nucleic Acid Testing Could Help Detect HIV, Hepatitis C in Tissue Donations, Study Says

Nucleic acid testing could help detect HIV, hepatitis C and other viruses in donated human tissue, according to a study published in the Aug. 19 issue of the New England Journal of Medicine, the Richmond Times-Dispatch reports. NAT, which was developed in 1999, currently is used to screen about 14 million units of donated blood each year (Hostetler, Richmond Times-Dispatch, 8/19). NAT can detect minute amounts of viral genetic material in pooled plasma samples by amplifying gene fragments of HIV-1 and hepatitis C virus. If a pool tests positive for either virus, the individual sample can be detected and removed from further processing, and the donor can be deferred and notified (Kaiser Daily HIV/AIDS Report, 9/24/01). Dr. Shimian Zou and colleagues from the American Red Cross, the Puget Sound Blood Center and the Northwest Tissue Center analyzed data from 11,391 tissue donors at several locations between 2000 and 2002 to determine the probability of undetected HIV, hepatitis B, hepatitis C and T-lymphotropic virus, according to Reuters Health. The researchers found that 0.093% of the samples tested positive for HIV; 0.299% tested positive for hepatitis B; 1.091% tested positive for hepatitis C; and 0.068% tested positive for human T-lymphotropic virus. The researchers concluded that with the current testing protocol there is a one in 55,000 probability that HIV-infected tissue will go undetected, according to Reuters Health (Reuters Health, 8/18). The addition of NAT to the tissue screening process could reduce the probability that donated tissue that is infected with HIV gets through the process to one in 173,000, according to the researchers, the AP/Las Vegas Sun reports. The researchers said that using NAT would cost $5 per tissue sample (Donn, AP/Las Vegas Sun, 8/18).

FDA Recommendations
FDA is moving toward recommending that NAT be used at all tissue banks, according to Dr. Jesse Goodman, head of the FDA unit that oversees the safety of the blood and tissue supply, the Times-Dispatch reports. "The lessons learned from blood apply to human tissue," Goodman writes in an accompanying NEJM editorial, according to the Times-Dispatch (Richmond Times-Dispatch, 8/19). FDA currently does not require blood or tissue banks to use NAT; however, many blood banks now "routinely" use the genetic testing in "cooperation" with FDA, and some tissue banks have begun using NAT in recent months, according the AP/Sun. "I think it's going to become the standard of practice, whether it's required or not," Margery Moogk, a board member of the American Association of Tissue Banks, said (AP/Las Vegas Sun, 8/18).

NAT Reduces HIV Risk in Donated Blood
In a second NEJM study, Dr. Susan Stramer and colleagues from the American Red Cross found that using NAT reduces the risk of donated blood that is infected with HIV or other viruses passing the screening process, Reuters Health reports. The researchers screened more than 37 million antibody-nonreactive units of donated blood using NAT to test for HIV and hepatitis C. The researchers discovered that 12 units tested positive for HIV, giving a rate of one HIV-positive unit per 3.1 million donations. Using an HIV p24 antigen test -- which U.S. blood banks previously used for routine blood screening -- the researchers discovered only two HIV-positive units. The researchers noted that approximately one in 230,000 units tested positive for hepatitis C using NAT. "[NAT] has helped prevent the transmission of approximately five HIV-1 infections and 56 hepatitis C infections annually and has reduced the residual risk of transfusion-transmitted HIV-1 and hepatitis C virus to approximately one in two million blood units," the researchers concluded (Reuters Health, 8/18). Barbara Alving, acting director of the National Heart, Lung and Blood Institute, said that NAT "enhances the safety of the nation's blood supply by further reducing risks" of transmitting HIV and hepatitis C (Agence France-Presse, 8/18). Alving added, "Risks to blood recipients from transfusion-transmitted viruses such as HIV and hepatitis are already extremely low, in part because of increased surveillance and improved testing" (NIH release, 8/19).