Human foamy virus DNA forms and expression in persistently infected Dami megakaryocytic cells.

We have characterized human foamy virus (HFV) proviral DNA and determined HFV expression in a persistent infection model, the Dami megakaryocytic cell line. Molecular studies were performed on parental persistently infected cells (Dami-P), as well as on derived clones (Dami-Cl). We report that in these nonlytic and non-HFV producer cells, viral DNA was found to be integrated into the cellular genome and that the few free proviral forms detected in Dami-P cells were deleted in their 5′ LTR. Our molecular analysis indicates the presence of undeleted 5′ LTR forms in the integrated provirus within a proviral population mainly composed of deleted forms. In addition, the deletion in the bell trans-activator gene, previously described by Saib et al.,1 was found to be highly predominant. However, in 5-iodo-2′-deoxyuridine treated Dami-Cl cultures, virus production occurred, providing evidence for the presence of complete viral genome. Analysis of HFV expression in Dami-Cl cells, by Northern blot and immunoprecipi...