Distinct modes of human immunodeficiency virus type 1 proviral latency revealed by superinfection of nonproductively infected cell lines with recombinant luciferase-encoding viruses
To study the basis of cellular latency of human immunodeficiency virus (HIV), we have used a recombinant luciferase-encoding HIV (HXB-Luc) to superinfect nonproductively HIV-1-infected human leukemic cell lines. HXB-Luc contains the Photinus pyralis luciferase gene in place of the nef gene and provides a highly sensitive, simple assay for HIV infection and expression. To circumvent any superinfection block in latently infected cells, we also generated viruses pseudotyped with murine leukemia virus amphotropic envelope (HXB-Luc:ampho). The parental uninfected lines, U937 and A3.01, from which the latently infected cell lines U1 and ACH-2, respectively, were derived could be readily infected with pseudotyped or nonpseudotyped reporter viruses. However, superinfection of U1 cells with either HXB-Luc or HXB-Luc:ampho resulted in only low levels of luciferase activity. Like the endogenous provirus, HXB-Luc provirus could be efficiently activated by phorbol ester treatment of HXB-Luc:ampho-superinfected U1 cells. In contrast, superinfection of ACH-2 cells resulted in active expression of the secondarily introduced virus even in unstimulated cells and luciferase production higher than in the parental cell line A3.01. Thus, the proviral latency in U1 cells appears to result from a defect in the cellular environment (a trans effect), whereas the latency in ACH-2 is specific to the integrated provirus and is probably a cis effect due to the site of integration. These results demonstrate distinct modes of proviral latency in these two cell line models and may have implications in our understanding of the regulation and significance of cellular latency in HIV infection.
© 1994 by the American Society for Microbiology. Received 17 September 1993/Accepted 13 October 1993 We thank David Ho and the Aaron Diamond AIDS Research Center for allowing us to utilize their BL-3 facilities. We also thank Nathaniel Landau for cells, plasmids, and technical advice; Ruth Connor and Marc Lenburg for technical advice; and Mark Feinberg for the R73 proviral construct. This work was supported by NIAID grant AI22346. B.K.C. was supported by a Medical Scientist Training Program grant, and K.S. was supported by an Aaron Diamond Foundation postdoctoral research fellowship.
Published - CHEjvir94.pdf