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What is the nucleic acid test (NAT)?

The nucleic acid test (NAT) system can detect the presence of bacteria and viruses (e.g. human immunodeficiency virus (HIV) and hepatitis C virus (HCV)) in blood using a semi-automated system and further ensures the safety of blood products, including fresh frozen plasma, red cells, and platelets by permitting earlier detection of infections in donors. The NAT system is capable of detecting a few more infectious donations than other current tests because it detects genetic material rather than antigens (proteins from the virus) or antibodies (immune response to the virus or bacteria). Detection of genetic material permits detection earlier in the infection since the appearance of antibodies requires time for the donor to develop an immune response, and detection of antigens requires time for a higher level of the organisms to appear in the bloodstream. This technology detects very small amounts of genetic material by copying it numerous times, resulting in amplification of the targeted material. For example, the test system can detect ribonucleic acid (RNA) from HIV-1 and HCV when tested in pools of 16 samples obtained from multiple donors. In a less automated format, it can also be used to test individual samples from whole blood donations. If a test pool is positive for either virus, the individual donations suspected of containing a virus can be identified and not transfused. The donor can be deferred from donating blood and notified.

 Donors of blood and plasma are tested for antibodies to HCV and antibodies to HIV. However, there is still a “window period” during which a donor can be infected but have negative results on these screening tests. With the use of NAT for HCV, the window period is reduced approximately 50 days (from an average of 57 days to 7 days). For HIV-1, the average window period with antibody testing is 22 days. This window period is reduced approximately 12 days with NAT (from an average of 22 days to 10 days).

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.