IDENTIFICATION OF LOW-LEVEL CONTAMINATION OF BLOOD AS BASIS FOR DETECTION OF HUMAN-IMMUNODEFICIENCY-VIRUS (HIV) DNA IN ANTI-HIV-NEGATIVE SPECIMENS

The significance of detection of human immunodeficiency virus (HIV) DN A by the polymerase chain reaction (PCR) in seronegative or seroconver ting (SC) subjects remains controversial. In a previously reported stu dy, we identified a case in which a specimen collected 12 months befor e seroconversion (pre-SC) was found repeatedly to be PCR positive in t hree experienced laboratories, while the 6-month pre-SC bleed was PCR- negative; PCR-based human leukocyte antigen (HLA)-DQA and -DRB typing of serial peripheral blood mononuclear cell (PBMC) samples from this c ase did not indicate a specimen mix-up or labeling error. To further i nvestigate this case, we used HIV env sequence and DNA heteroduplex ge l-shift analyses to characterize HIV quasispecies present in serial pr e- and post-SC specimens. HIV env sequences and gel-shift pattern anal yses from the 12-month pre-SC versus post-SC samples indicated that ma rkedly distinct quasispecies were present, suggesting possible abortiv e infection followed by reinfection and subsequent seroconversion. How ever, the HIV burden of this pre-SC sample was very low (1 provirus/10 (6) PBMCs), and the quasispecies was highly heterogeneous, findings su ggesting long-term rather than recent HIV infection. To test the hypot hesis that the index pre-SC sample was PCR positive owing to trace blo od contamination during initial processing, we analyzed the three sero positive samples collected on the same date in 1985. One of these samp les was highly related to the index pre-SC sample by env sequence and gel-shift methodologies. The source of contamination was further verif ied by PCR detection (using enhanced-sensitivity allele-specific prime rs) of HLA DR2 sequences unique to the contaminating source subject in the 12-month pre-SC PBMC sample from the index subject. This study sh ows that trace contamination during blood processing represents an add itional basis for false-positive HIV PCR results and illustrates the u sefulness of DNA heteroduplex gel-shift analysis and HLA allele-specif ic PCR in investigating such cases. NATIONAL GENBANK ACCESSION Numbers for these sequences: L20371 through L20380, inclusive.