Nicotinamide activates latent HIV-1 ex vivo in ART suppressed individuals, revealing higher potency than the association of two methyltransferase inhibitors, chaetocin and BIX01294

Abstract

Background: Latent HIV-1 is a major hurdle in obtaining HIV-1 sustained virological remission (SVR). Here we explored histone deacetylation inhibition property of nicotinamide (NAM; n=17) for the first time in comparison to a combination of methyltransferase inhibitors (MTIs; Chaetocin and BIX01294; n=25) to reactivate latent HIV ex vivo in CD8-depleted PBMCs from antiretroviral treated aviremic individuals.

Results: NAM reactivated HIV-1 from 13/17 (76.4%) samples compared to 20/25 (80.0%) using MTIs with mean viral load (VLs) of 4.32 and 3.22 log₁₀ RNA copies/mL, respectively (p=0.004). Mean purging time after NAM and MTIs stimulation was 5.1 and 6.75 days, respectively (p=0.73). Viral purging in autologous cultures exhibited blunted HIV recovery with fluctuating VLs followed by a complete viral extinction when expanded in allogenic system. Electron microscopy from five supernatants revealed anomalous viral particles, with lack of complete viral genomes when characterized by ultradeep sequencing through metagenomics approach (n=4).

Conclusion: NAM alone was more potent HIV-1 activator than combination of MTIs, with potential of clinical use.

Keywords: BIX01294; Chaetocin; Histone deacetylases inhibitor; Latency reversal agents; Methyltransferase inhibitors; Nicotinamide.

Fig. 1

Ex vivo treatment with MTIs and NAM and their comparison. (A) Graph showing the Log₁₀ viral load (copies/mL) of the culture supernatant treated with MTIs, (B) Graph showing the Log₁₀ viral load (copies/mL) of the culture supernatant treated with NAM, (C) Comparison of NAM + MTIs to break latency with respect to time. (D) Comparison of NAM + MTIs with respect to viral load.

Fig. 2

Characterization of the purged viruses using Next Generation sequencing with Metagenomics Methodology for de novo HIV characterization on supernatant samples containing purged HIV-1 particles of 4 selected samples following in vitro treatment with the MTIs association (patients S7 and S2, panels A and C) and NAM (patients NA5 and NA8, panels B and D) showing uneven coverage of HIV genome. Panels E and F shows the electronic microscopy result performed in the supernatant of samples S2 and NA8 respectively showing anomalous HIV particles.