ABSENCE OF HIV INFECTION IN BLOOD-DONORS WITH INDETERMINATE WESTERN BLOT TESTS FOR ANTIBODY TO HIV-1

To determine whether apparently healthy persons who have had repeatedly reactive enzyme immunoassays and an indeterminate Western blot assay for antibody to the human immunodeficiency virus type 1 (HIV-1) are infected with HIV-1 or HIV-2, we studied 99 such volunteer blood donors in a low-risk area of the country. The subjects were interviewed about HIV risk factors. Coded blood specimens were tested again for HIV-1 antibody (by two different enzyme immunoassays, a Western blot assay and a radioimmunoprecipitation assay) and for HIV-2 antibody by enzyme immunoassay, for HIV-1 by the serum antigen test, for HIV-1 by culture, for human T-cell leukemia virus Type I or II antibody by enzyme immunoassay, and for sequences of HIV DNA by the polymerase chain reaction. Of the 99 blood donors, 98 reported no risk factors for HIV-1 infection; 1 donor had used intravenous drugs. After a median of 14 months (range, 1 to 30) from the time of the initial test, 65 subjects (66 percent) were still repeatedly reactive for HIV-1 antibody on at least one immunoassay. In 91 subjects (92 percent) the Western blot results were still indeterminate, whereas in 8 they were negative. No donor met the criteria for a positive Western blot assay for HIV-1, and none had evidence of HIV-1 or HIV-2 infection on culture or by any other test. We conclude that persons at low risk for HIV infection who have persistent indeterminate HIV-1 Western blots are rarely if ever infected with HIV-1 or HIV-2. LICENSED enzyme immunoassay kits for screening the blood of volunteer blood donors for antibody to the human immunodeficiency virus type 1 (HIV-1) have been available since March 1985.1 The blood from donors who have been found to be repeatedly reactive on an enzyme immunoassay for HIV-1 antibody has not been used in transfusion or manufactured into other products capable of transmitting infectious agents.2 To verify the presence of HIV-1 antibody in a repeatedly reactive sample, the Western blot assay3 has most often been used as a confirmatory test in the United States.4 This assay typically reveals six to nine characteristic… © 1990, Massachusetts Medical Society. All rights reserved.