False-positive human immunodeficiency virus type 1 western blot tests in noninfected blood donors.

BACKGROUND: The manufacturers' criteria for a positive human immunodeficiency virus type 1 (HIV-1) Western blot (WB) test were recently revised to require reactivity to only two of the following bands: p24, gp41, and gp120/160. In a recent report, low-risk blood donors were identified in whom nonspecific reactivity to multiple env antigens in WB testing resulted in apparently false-positive WBs by these criteria. The present study was conducted to verify the existence of false-positive WBs among noninfected donors and to assess the extent of this problem. STUDY DESIGN AND METHODS: Four donors classified as WB-positive on the basis of env-only (3 cases) or p24/env-only (1 case) patterns were investigated. Index and/or follow-up specimens were tested by polymerase chain reaction (PCR), by overlapping recombinant env antigens and synthetic peptides in enzyme immunoassays, and by deglycosylated and denatured antigen WBs. WB records from American Red Cross blood centers were reviewed to determine the frequency of env-only and p24/env-only patterns, relative to all positive WBs, from 1988 through 1993. RESULTS: The four index-case donors denied risk and had stable WB reactivity during follow-up. HIV PCR was negative in all. Env reactivity was restricted to nonglycosylated gp41 epitopes; no gp120-specific reactivity was detected. For three of the four donors, env reactivity was mapped to a 20-amino acid N-terminal epitope of gp41. The rate of detecting WBs with these false-positive patterns increased from 0.6 percent of all positive WBs from 1988 to 1990 (4/776) to 8 percent in 1991 and 1992 (52/683), and then it declined to 6 percent in 1992 and 1993 (47/783). Env-only patterns predominated in 1991 and 1992, whereas p24/env-only patterns were more frequent following implementation of combined anti-HIV-1/HIV type 2 enzyme immunoassays in 1992. CONCLUSION: Low-risk blood donors can have false-positive results on WB tests. Increased detection of env-only and p24/env-only WBs appears related to the enhanced sensitivity of newer enzyme immunoassays to gp41 and p24 antibodies. Donors with these patterns should undergo follow-up testing to document the presence or absence of HIV infection.

Prevalence of hepatitis C virus RNA in organ donors positive for hepatitis C antibody and in the recipients of their organs.

BACKGROUND: There is a high prevalence of liver disease among the recipients of organs from donors with antibodies to hepatitis C virus (HCV). We undertook a study to determine the frequency of persistent HCV infection, as indicated by the presence of HCV RNA, among both cadaveric organ donors positive for antibodies to HCV (anti-HCV) and the recipients or organs from these donors. METHODS: Serum samples from donors and recipients were tested for HCV RNA with the reverse transcriptase polymerase chain reaction, with use of primers from the 5' untranslated region of the HCV genome, and for anti-HCV with the first-generation enzyme-linked immunosorbent assay (ELISA) and two second-generation tests. RESULTS: HCV RNA was detected in 9 of the 11 organ donors (82 percent) with a positive first-generation ELISA for anti-HCV. Among the organ recipients, the prevalence of HCV RNA increased after transplantation: 7 of 26 patients (27 percent) had positive samples before transplantation, as compared with 23 of 24 patients (96 percent) after transplantation (P less than 0.001). Among 13 recipients who were HCV RNA-negative before receiving organs from the nine HCV RNA-positive donors, HCV infection was detected in all 13 after transplantation, and anti-HCV developed in 8 (62 percent). On the basis of a positive test for HCV RNA, the maximal sensitivity of the three anti-HCV tests was 57 percent (positive in 4 of 7 patients with end-stage organ failure) before transplantation and 70 percent (positive in 16 of 23 patients) after transplantation. CONCLUSIONS: Nearly all the recipients of organs from anti-HCV-positive donors become infected with HCV. The current tests for anti-HCV antibodies underestimate the incidence of transmission and the prevalence of HCV infection among immunosuppressed organ recipients.

Examination of whether persistently indeterminate human immunodeficiency virus type 1 Western immunoblot reactions are due to serological reactivity with bovine immunodeficiency-like virus.

The bovine lentivirus, known as bovine immunodeficiency-like virus (BIV), is genetically, structurally, and antigenically related to human immunodeficiency virus type 1 (HIV-1). It is not known whether sera from persons exposed to BIV proteins would show either positive or indeterminate reactivity on HIV-1 antibody tests. We used a BIV Western blot (immunoblot) analysis to examine human sera characterized as HIV-1 antibody positive, HIV-1 antibody negative, HIV-1 persistently indeterminate, HIV-1 p17 antibody positive only, HIV-1 p24 antibody positive only, human T-cell leukemia virus type 1 (HTLV-1) p19 antibody positive only, or HTLV-1 p24 antibody positive only. None of these sera were positive by Western blot to BIV-specific proteins. Many of these sera, however, displayed strong reactivities to bovine cell culture antigens on blots prepared from both mock-infected and BIV-infected cell cultures. The HIV-1 p17 and p24 antibody-positive and the HTLV-1 p19 and p24 antibody-positive sera were further examined by Western blot to bovine leukemia virus (BLV) and were found to be negative. We examined sera from laboratory personnel at risk for BIV exposure, including two laboratory workers who were exposed to BIV by accidental injection with BIV-infected cell culture material, and found no evidence of seroconversion to BIV-specific proteins. We tested 371 samples of fetal bovine sera, each sample representing serum pooled from one to three fetuses. All samples were negative by BIV Western blot. To date, we have not detected any human sera with antibody to BIV-specific proteins. Our data indicate that persistently indeterminate results on HIV-1 Western blot are not caused by a human antibody response to BIV proteins.