REVERSION OF A POLYMERASE-DEFECTIVE INTEGRATED HIV-1 GENOME

The 8E5 clonal cell line, derived from HIV-1-infected CEM cells, carri es a single, reverse transcriptase (RT)-defective copy of an integrate d HIV genome. The absence of RT production is a consequence of a frame shift in the pol gene, due to the addition of a single base at positi on 3241. We report here that 8E5 cells produce an infectious virus tha t can be serially passaged on CD4+ lymphoid cells. This virus (8E5R) i s RT positive, but displays a slow replication profile, together with a reduced cytopathic effect. The nucleotide sequence of a segment of t he pol region produced by PCR amplification of DNA from 8E5R-infected cells shows that the single nucleotide insertion characteristic of the 8E5 genome had been corrected. The same reversion event was also foun d to occur in most single-cell clones derived from the 8E5 cell line. Because this cell line is used in many labortories, notably as a stand ard for PCR quantitation, and is generally considered as unable to pro duce infectious virus, our findings should prompt investigators to use particular care in the handling of these cells.