Blood donors with indeterminate anti-p24gag reactivity in HIV-1 western blot: absence of infectivity to transfused patients and in virus culture.

During a follow-up period of 23-40 months, 7 regular blood donors had persistently, and 4 had intermittently indeterminate anti-p24gag reactivity in human immunodeficiency virus (HIV)-1 Western Blot. Serological testing and viral cultures revealed that these donors had no signs of infection for HIV-1, HIV-2, human T-cell lymphotropic virus (HTLV)-4, and HTLV-1. Extensive interviewing and physical examination of these donors revealed neither risk factors, nor signs of HIV infection in the tested donors. Ten recipients, who were transfused with blood products from 6 of these 11 anti-p24gag-positive donors, were traced back. Six months after transfusion, no serological or clinical signs of HIV-1, HIV-2, or HTLV-1 infection were observed in these patients. It is concluded that blood donors with persistent or intermittent anti-p24gag reactivity in HIV-1 Western Blot, without development of antibodies to other HIV-encoded proteins in later blood samples, do not transmit the described retroviruses to transfused patients.