Detection of HIV-1 Window Period Infection in Blood Donors Using Borderline Anti-HIV Results, HIV-1 Proviral DNA PCR, and HIV-1 Antigen Test
WACHANAN WONGSENA, M.Sc.*, MONGKOL KUNAKORN, M.D.**, SRIVILAI TANPRASERT, M.D.***, BENCHA PETCHCLAI, M.D.**
Affiliation : * Diagnostic Laboratory, Khon Kaen Hospital, Khon Kaen 41000, ** Immunology Laboratory, Department of Pathology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, *** National Blood Center, Thai Red Cross Society, Bangkok 10330, Thailand.
Abstract Prevention of transmission of HIV -1 via blood transfusion has been carried out by the National Blood Center by screening donated blood with anti-HIV and HIV antigen tests. To increase the safety measure, detection of proviral DNA by PCR has been proposed; however, it was impractical to test all samples by PCR. From August 1994 to September 1995, there were 296,169 blood donors with 0.32 per cent prevalence of anti-HIV positive. From these donors, 153 samples of which the anti-HIV enzyme immunoassay optical density (OD) between cutoff and 80 per cent of cutoff value (borderline results) were selected for PCR testing. One out of 153 border- line cases showed positive by PCR test for HIV-1 proviral DNA. However, this case was also positive by HIV antigen test. Therefore, most of the samples with borderline anti-HIV results were true negative for HIV infection. On the other hand, there were 8 HIV antigen positive samples which had anti-HIV OD below the borderline value determined in this study. This finding con- firmed the necessity of using both the anti-HIV and HIV antigen tests for screening of donated blood.
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