APOBEC3G-depleted resting CD4+ T cells remain refractory to HIV1 infection

Francesca Santoni de Sio, Didier Trono
2009
Article

Résumé

BACKGROUND: CD4+ T lymphocytes are the primary targets of HIV1 but cannot be infected when fully quiescent, due to a post-entry block preventing the completion of reverse transcription. Chiu et al. recently proposed that this restriction reflects the action of APOBEC3G (A3G). They further suggested that T cell activation abrogates the A3G-mediated block by directing this protein to a high molecular mass complex. METHODOLOGY/PRINCIPAL FINDINGS: In the present work, we sought to explore further this model. However, we found that effective suppression of A3G by combined RNA interference and expression of HIV1 Vif does not relieve the restrictive phenotype of post-activation resting T cells. We also failed to find a correlation between HIV resistance and the presence of A3G in a low molecular complex in primary T cells. CONCLUSIONS/SIGNIFICANCE: We conclude that A3G is unlikely to play a role in the HIV restrictive phenotype of quiescent T lymphocytes.

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https://infoscience.epfl.ch/record/142242?ln=fr

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In contrast to oncoretroviruses, lentiviruses such as human immunodeficiency virus 1 (HIV-1) are able to integrate their genetic material into the genome of nonproliferating cells that are metabolically active. Likewise, vectors derived from HIV-1 can transduce many types of nonproliferating cells, with the exception of some particular quiescent cell types such as resting T cells. Completion of reverse transcription, nuclear import, and subsequent integration of the lentivirus genome do not occur in these cells unless they are activated via the T-cell receptor (TCR) or by cytokines or both. However, to preserve the functional properties of these important gene therapy target cells, only minimal activation with cytokines or TCR-specific antibodies should be performed during gene transfer. Here we report the characterization of HIV-1-derived lentiviral vectors whose virion surface was genetically engineered to display a T cell-activating single-chain antibody polypeptide derived from the anti-CD3 OKT3 monoclonal antibody. Interaction of OKT3 IgGs with the TCR can activate resting peripheral blood lymphocytes (PBLs) by promoting the transition from G(0) to G(1) phases of the cell cycle. Compared to unmodified HIV-1-based vectors, OKT3-displaying lentiviral vectors strongly increased gene delivery in freshly isolated PBLs by up to 100-fold. Up to 48% transduction could be obtained without addition of PBL activation stimuli during infection. Taken together, these results show that surface-engineered lentiviral vectors significantly improve transduction of primary lymphocytes by activating the target cells. Moreover these results provide a proof of concept for an approach that may have utility in various gene transfer applications, including in vivo gene delivery.

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