Background: The infectious status of persons with an indeterminate human immunodeficiency virus type 1 (HIV-1) Western blot must be established.
Study design and methods: Evaluation of the CD4 and CD8 T-cell subsets and the expression of HIV-1-integrated sequences by Southern blot and polymerase chain reaction were studied in a group of low-risk subjects with an indeterminate Western blot.
Results: From a total of 45,000 blood donors and 50 patients with chronic renal failure on hemodialysis who were tested during the period of 1985 through 1990, 50 sera (0.1%) had an indeterminate Western blot. A low CD4:CD8 ratio (0.7-1.2) was detected in 14 of 24 tested subjects, whereas the unfractionated and adherence-enriched cells of 7 (32%) and 5 (23%) of 22 patients, respectively, could be stained with a p24 monoclonal antibody. A transient positive culture was detected in 3 of 20 subjects, but these viral isolates could not be transmitted to CEM-A310 cells. Ultracentrifuged culture supernatants hybridized under high-stringency conditions with genomic gag-pol (4 cases), env (3 cases), and tat (1 case) cDNA fragments of the HXB2 HIV-1 clone. In one case, DNA obtained from adherent but not unfractionated mononuclear cells contained 3.3- and 3.9-kb env- and gag-pol-related HIV-1 sequences, respectively; these sequences were heavier than expected. Polymerase chain reaction analysis for gag and pol but not env sequences was positive in 1 and 2 of 7 cases, respectively. A female patient with a positive viral culture and who was positive for pol in polymerase chain reaction demonstrated a full seroconversion 19 months later.
Conclusion: The results strongly suggest that, rarely, some low-risk subjects with indeterminate Western blot results might be infected with low-level replicative strains or HIV-related viruses; thus, an exhaustive immunologic and virologic workup is needed for the investigation of these subjects.