Human macrophages support persistent transcription from unintegrated HIV-1 DNA

Abstract

Retroviruses require integration of their RNA genomes for both stability and productive viral replication. In HIV infection of non-dividing, resting CD4 T cells, where integration is greatly impeded, the reverse transcribed HIV DNA has limited biological activity and a short half-life. In metabolically active and proliferating T cells, unintegrated DNA rapidly diminishes with cell division. HIV also infects the non-dividing but metabolically active macrophage population. In an in vitro examination of HIV infection of macrophages, we find that unintegrated viral DNA not only has an unusual stability, but also maintains biological activity. The unintegrated linear DNA, 1-LTR, and 2-LTR circles are stable for at least 30 days. Additionally, there is persistent viral gene transcription, which is selective and skewed towards viral early genes such as nef and tat with highly diminished rev and vif. One viral early gene product Nef was measurably synthesized. We also find that independent of integration, the HIV infection process in macrophages leads to generation of numerous chemokines.

M-CSF Inhibits Anti–HIV-1 Activity of IL-32, but They Enhance M2-like Phenotypes of Macrophages

“…3B). During an early and essential step for HIV-1 replication, the HIV-1 RNA genome is reverse transcribed into dsDNA, which is subsequently integrated into the host chromatin (31). It appeared that IL-32g inhibited HIV-1 replication by affecting the integration step, because IL32g-treated macrophages showed slow and weak viral genome integration when compared with M-CSF-treated macrophages (Fig.…”

“…3C), viral integration was assessed by Alu-long-terminal repeat (Alu-LTR) nested PCR (31). The viral stock of the AD8 strain was prepared by transfecting the proviral plasmid into 293 cells.…”

Comparative antiviral activity of integrase inhibitors in human monocyte-derived macrophages and lymphocytes

“…This biological effect could be correlated to the peculiar characteristics of HIV-1 replication in M/M, which is quite different from that observed in CD4+ T lymphocytes (Aquaro et al, 2002a,b;Badley et al, 1997;Bagnarelli et al, 1996;Garaci et al, 1999;Gendelman et al, 1986;Michelini et al, 2010;Orenstein et al, 1988). Indeed, M/M are resting, terminally differentiated cells that undergo replication only under very peculiar conditions and situations; this makes the whole integration phenomenon more difficult, as it occurs during the replication cycle of cells (Kelly et al, 2008). Therefore, it is conceivable that HIV integration, occurring slower in M/M due to the lower cycle metabolism, should be more easily perturbed by concentrations of INIs even lower than those effective in replicating cells (Kelly et al, 2008).…”

“…Indeed, M/M are resting, terminally differentiated cells that undergo replication only under very peculiar conditions and situations; this makes the whole integration phenomenon more difficult, as it occurs during the replication cycle of cells (Kelly et al, 2008). Therefore, it is conceivable that HIV integration, occurring slower in M/M due to the lower cycle metabolism, should be more easily perturbed by concentrations of INIs even lower than those effective in replicating cells (Kelly et al, 2008).…”

Epigenetic activation of unintegrated HIV-1 genomes by gut-associated short chain fatty acids and its implications for HIV infection

“…The passive, yet rapid, loss of episomal HIV-1 forms in dividing cells, such as activated T cells, is only part of a complex mechanism rendering nonintegrating HIV-1 forms replication-defective. This view is premised on a number of in vitro studies demonstrating the stability of circular HIV-1 episomes in T cell lines and the persistence of integrasedeficient HIV-1 in nondividing primary macrophages (2,3). Supporting this notion are early reports describing the accumulation of episomal HIV-1 forms in the brain tissue of AIDS patients and more recent studies demonstrating the persistence of nonintegrating HIV-1 vector forms in various rodent tissues in vivo (4).…”