Detection of unintegrated human immunodeficiency virus type 1 DNA in persistently infected CD8+ cells

The presence of unintegrated viral DNA has been reported in cells persistently infected by lentiviruses, including human immunodeficiency virus type 1 (HIV-1). We confirm that CD8+ cells can be productively and persistently infected by HIV-1 for up to 4 months, as determined by secretion of viral core antigen p24 into the extracellular medium and by indirect immunofluorescence. The expression of the external viral glycoprotein gp120 at the surface of these cells was demonstrated by two-colour flow cytometry. Progeny virions recovered from CD8+ cells were infectious in CD4+ T cells. Despite an absence of significant cytopathology, these chronically infected CD8+ cells were shown to harbour unintegrated HIV-1 DNA, as detected by quantitative PCR. Both linear and circular forms of the extrachromosomal viral genome were present in infected CD8+ cells, as early as 3 weeks before a peak in viral replication. These findings provide evidence that the presence of unintegrated viral DNA during lentiviral infection may not always correlate with c.p.e.