New Diagnostic Testing Measures
September 21, 2001
FDA Approves First Nucleic Acid Test (NAT) Systems to Screen Plasma for Human Immunodeficiency Virus (HIV) and Hepatitis C Virus (HCV)The Food and Drug Administration has licensed the first nucleic acid test (NAT) systems intended for screening of plasma donors. These test systems are expected to further ensure the safety of plasma-derived products by permitting earlier detection of HIV and HCV infections in donors.
Although effective procedures for virus inactivation are required in the manufacturing of all U.S. licensed plasma derivatives, removal of potentially infectious donations through donor screening adds a safeguard by limiting the amount of virus contamination that the manufacturing process must clear.
NAT is a recently developed technology that allows detection of very small amounts of genetic material (DNA or RNA) by a process of massive copying (amplification) of a gene fragment. The approved test systems permit highly sensitive detection of RNA from HIV-1 and HCV in test pools of 512 plasma samples obtained from multiple donors. Currently, donors of blood and plasma are tested for antibodies to HCV, antibodies to HIV, and HIV-1 antigens, which are the virus' own proteins. However, there is still a "window period" during which a donor can be infected, but have negative screening tests. With the use of NAT for HCV, the "window period" for detection of HCV is reduced by 57 days (from an average of 82 days to 25 days). For HIV-1, the average window period with antibody tests is 22 days. Antigen testing cuts the window period to approximately 16 days and NAT further reduces this period to 12 days.
Since 1997, FDA and other government research agencies have encouraged the investigation of NAT technology through the use of experimental protocols, in the hope of improving the safety of plasma derivatives and further reducing the risk of an infectious unit of blood being transfused. For more information, please call the STEP Talkline at 1-877-597-STEP or look at these related websites: http://www.alphather.com/ or http://www.ngi.com/.
Source: National Genetics Institute, Alpha Therapeutic Corporation and the FDA.
This article was provided by Seattle Treatment Education Project. It is a part of the publication STEP Ezine.