Inhibition of the in vitro infectivity and cytopathic effect of human foamy virus by dideoxynucleosides

ABSTRACT Human foamy virus (HFV) is a human retrovirus that has not been clearly associated with human disease. In this study, we tested the capacity of nucleoside derivatives to inhibit the infectivity and cytopathic effect of HFV in T-lymphoblastoid cells in vitro. H9 cells showed a dramatic cytopathic effect 3 weeks after exposure to HFV. At this time, viral infection was demonstrated by detection of viral antigens by immunofluorescence staining, release of reverse transcriptase activity (RT) in the supernatant, detection of typical viral particles by electron microscopy, and presence of proviral DNA by Southern blot analysis. H9 cells were pretreated with dideoxycytidine (ddC), dideoxyinosine (ddI), or azidothymidine (AZT) at various concentrations before HFV infection. ddC could not completely suppress viral replication at low concentrations, and inhibited cell proliferation at higher concentrations, ddl partially inhibited the formation of giant cells at 10 μM, with 95% inhibition of RT in the super...