Replication of Primary HIV-1 Isolates Is Inhibited in PM1 Cells Expressing sCD4-KDEL

Abstract

Expression of a soluble CD4 molecule (sCD4-KDEL) containing a specific retention signal for the endoplasmic reticulum was shown previously to block propagation of the HIV-1MNprototype strain in a transformed T cell line. However, the virus present in HIV-1-infected individuals is more closely represented by primary HIV-1 isolates which, unlike the HIV-1MNstrain, have not been adapted to growth in cell lines. To determine if sCD4-KDEL could block replication of primary isolates we used the PM1 cell line that has been shown to propagate primary isolates without adaptation. Here we show that the replication of four primary HIV-1 isolates was strongly inhibited in PM1 cells that expressed sCD4-KDEL under control of the HIV-1 LTR. Infection with primary HIV-1 isolates induced sCD4-KDEL expression driven by the LTR, HIV-1 spread was dramatically reduced, and reverse transcriptase activity in the cell culture supernatants was greatly diminished. sCD4-KDEL, therefore, represents a potent inhibitor of HIV-1 replication for gene therapy-based approaches for the treatment of AIDS.