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New ex vivo approaches distinguish effective and ineffective single agents for reversing HIV-1 latency in vivo



HIV-1 persists in a latent reservoir despite antiretroviral therapy (ART)1,2,3,4,5. This reservoir is the major barrier to HIV-1 eradication6,7. Current approaches to purging the latent reservoir involve pharmacologic induction of HIV-1 transcription and subsequent killing of infected cells by cytolytic T lymphocytes (CTLs) or viral cytopathic effects8,9,10. Agents that reverse latency without activating T cells have been identified using in vitro models of latency. However, their effects on latently infected cells from infected individuals remain largely unknown. Using a new ex vivo assay, we demonstrate that none of the latency-reversing agents (LRAs) tested induced outgrowth of HIV-1 from the latent reservoir of patients on ART. Using a quantitative reverse transcription PCR assay specific for all HIV-1 mRNAs, we demonstrate that LRAs that do not cause T cell activation do not induce substantial increases in intracellular HIV-1 mRNA in patient cells; only the protein kinase C agonist bryostatin-1 caused significant increases. These findings demonstrate that current in vitro models do not fully recapitulate mechanisms governing HIV-1 latency in vivo. Further, our data indicate that non-activating LRAs are unlikely to drive the elimination of the latent reservoir in vivo when administered individually.

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Figure 1: LRAs do not induce outgrowth of latent HIV-1.
Figure 2: LRAs do not consistently induce HIV-1 mRNA production in cells from HIV-1 infected individuals on ART.
Figure 3: A primary CD4+ T cell model of HIV-1 latency is responsive to LRAs.
Figure 4: Vorinostat induces transcripts containing HIV-1 gag sequence but not HIV-1 mRNA in cells from HIV-1–infected individuals on ART.

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We thank H. McHugh and A. Devadason for assistance with study participants. Funding was provided by the Martin Delaney Collaboratory of AIDS Researchers for Eradication and the Delaney AIDS Research Enterprise (US National Institutes of Health grants AI096113 and AI096109 (R.F.S.)), the Foundation for AIDS Research grants 108165-50-RGRL (R.F.S.) and 108707-54-RKRL (C.M.D.), the Johns Hopkins Center for AIDS Research (J.D.S.), US National Institutes of Health grant 43222 (R.F.S.) and the Howard Hughes Medical Institute (R.F.S.).

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G.M.L., C.K.B. and R.F.S. designed experiments; G.M.L. and C.K.B. performed experiments; C.M.D. obtained institutional review board approval and managed study participant recruitment; G.M.L., C.K.B., J.D.S. and R.F.S. analyzed the data and wrote the manuscript.

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Correspondence to Robert F Siliciano.

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The authors declare no competing financial interests.

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Bullen, C., Laird, G., Durand, C. et al. New ex vivo approaches distinguish effective and ineffective single agents for reversing HIV-1 latency in vivo. Nat Med 20, 425–429 (2014).

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