[Amplification of the activity of HIV-1 isolates purified from seropositive children after cryopreservation of persistently-infected cells].

: HIV-1 strains MC-1974 and MC-1978 were isolated from children infected in hospital. Both children presented with symptoms of HIV infection by the moment the blood samples for virus isolation were collected. In vitro the isolated strains showed weak infective activity and caused no cytopathic effect in sensitive cells. It may be explained by azidothymidine antiviral therapy or by initial immunodeficient status of both children not caused by HIV infection. Virus activity was enhanced in both cultures after reactivation of Jurkat-tat cells persistently infected with MC-1974 and MC-1978 strains after cryopreservation. Viruses isolated from culture fluid effectively infected Jurkat-tat cells. The infection was associated with formation of syncytia, accumulation of viral particles detected by electron microscopy and of intracellular antigens detected by fluorescent antibody technique and by immunoblotting. The results suggest the presence in the body of infected children and in Jurkat-tat-1974 and Jurkat-tat-1978 persistent lines of a viral genome containing all virusspecific genes necessary for productive expression of HIV-1.