Jurkat-tat but not other tat-expressing cell lines support replication of slow/low type HIV.

The Jurkat-tat cell line, carrying the transactivator (tat) gene of HIV-1 IIIB and thus constitutively expressing the tat protein, has the capacity to support replication of HIV isolates obtained from asymptomatic individuals, so called slow/low (s/l) type virus. A major characteristic of the s/l isolates in vitro is their inability to continuously replicate in cells of CD4+ established lines. In contrast, virus isolates designated rapid/high (r/h) obtained from patients in advanced stages of the HIV-infection do not show this restriction in replicative capacity. To analyze whether introduction of the tat protein into certain cell types or an over-expression of the tat protein would render cells permissive for s/l virus replication, the tat gene was transfected into cells of monocytoid and T cell origin. The resulting cell lines were then tested for their susceptibility to infection with s/l and r/h type HIV-1 isolates. The results conclusively show that mere constitutive expression of the tat protein in established CD4+ cell lines will not provide conditions allowing for continuous replication of s/l type virus. Thus, the Jurkat-tat cell line is a unique cell system for long-term propagation of this type of virus. In addition, it is a suitable system to study virus-host cell interactions and control of virus replication.