Detection of HIV–1 RNA in Two Consecutive Blood Donations Screened Negative for HIV Antibodies

Abstract

Background and Objectives: An unusual serological pattern of HIV–1 seroconversion in a blood donor is described. The seroconversion panel was used to investigate the sensitivity of existing screening assays. Materials and Methods: A volunteer blood donor who had given blood 79 times was diagnosed anti–HIV–1–antibody–positive. The heteroduplex mobility assay identified a subtype B HIV–1 strain. The frozen plasmas from the last four blood donations had been kept at –30°C. They were thawed and aliquoted for subsequent testing. Results: The last two blood donations contained HIV–1 RNA, 2,800 copies/ml (October 26) and 170 copies/ml (November 23). Weak anti–p24 antibodies were detected by Western blot in the October 26 sample, and a clear p24 reactivity along with a faint gp160 reactivity was observed on November 23. HIV p24 antigen was undetectable in both samples. Out of 13 screening assays, only 6 gave positive results on the November sample and 7 negative results which were obtained by 1 competitive enzyme immunoassay (EIA) and 6 of the 9 sandwich EIAs. Conclusion: Most sandwich EIAs gave prolonged false–negative results in the present case. p24 antigen testing was negative and would not have reduced the risk of HIV transmission.