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 degrees 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.