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.

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

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.

Pace of Coreceptor Tropism Switch in HIV-1-Infected Individuals after Recent Infection.

HIV-1 entry into target cells influences several aspects of HIV-1 pathogenesis, including viral tropism, HIV-1 transmission and disease progression, and response to entry inhibitors. The evolution from CCR5- to CXCR4-using strains in a given human host is still unpredictable. Here we analyzed timing and predictors for coreceptor evolution among recently HIV-1-infected individuals. Proviral DNA was longitudinally evaluated in 66 individuals using Geno2pheno[coreceptor] Demographics, viral load, CD4+ and CD8+ T cell counts, CCR5Δ32 polymorphisms, GB virus C (GBV-C) coinfection, and HLA profiles were also evaluated. Ultradeep sequencing was performed on initial samples from 11 selected individuals. A tropism switch from CCR5- to CXCR4-using strains was identified in 9/49 (18.4%) individuals. Only a low baseline false-positive rate (FPR) was found to be a significant tropism switch predictor. No minor CXCR4-using variants were identified in initial samples of 4 of 5 R5/non-R5 switchers. Logistic regression analysis showed that patients with an FPR of >40.6% at baseline presented a stable FPR over time whereas lower FPRs tend to progressively decay, leading to emergence of CXCR4-using strains, with a mean evolution time of 27.29 months (range, 8.90 to 64.62). An FPR threshold above 40.6% determined by logistic regression analysis may make it unnecessary to further determine tropism for prediction of disease progression related to emergence of X4 strains or use of CCR5 antagonists. The detection of variants with intermediate FPRs and progressive FPR decay over time not only strengthens the power of Geno2pheno in predicting HIV tropism but also indirectly confirms a continuous evolution from earlier R5 variants toward CXCR4-using strains.IMPORTANCE The introduction of CCR5 antagonists in the antiretroviral arsenal has sparked interest in coreceptors utilized by HIV-1. Despite concentrated efforts, viral and human host features predicting tropism switch are still poorly understood. Limited longitudinal data are available to assess the influence that these factors have on predicting tropism switch and disease progression. The present study describes longitudinal tropism evolution in a group of recently HIV-infected individuals to determine the prevalence and potential correlates of tropism switch. We demonstrated here that a low baseline FPR determined by the Geno2pheno[coreceptor] algorithm can predict tropism evolution from CCR5 to CXCR4 coreceptor use.

Estimation of genetic diversity in viral populations from next generation sequencing data with extremely deep coverage.

BACKGROUND: In this paper we propose a method and discuss its computational implementation as an integrated tool for the analysis of viral genetic diversity on data generated by high-throughput sequencing. The main motivation for this work is to better understand the genetic diversity of viruses with high rates of nucleotide substitution, as HIV-1 and Influenza. Most methods for viral diversity estimation proposed so far are intended to take benefit of the longer reads produced by some next-generation sequencing platforms in order to estimate a population of haplotypes which represent the diversity of the original population. The method proposed here is custom-made to take advantage of the very low error rate and extremely deep coverage per site, which are the main features of some neglected technologies that have not received much attention due to the short length of its reads, which precludes haplotype estimation. This approach allowed us to avoid some hard problems related to haplotype reconstruction (need of long reads, preliminary error filtering and assembly). RESULTS: We propose to measure genetic diversity of a viral population through a family of multinomial probability distributions indexed by the sites of the virus genome, each one representing the distribution of nucleic bases per site. Moreover, the implementation of the method focuses on two main optimization strategies: a read mapping/alignment procedure that aims at the recovery of the maximum possible number of short-reads; the inference of the multinomial parameters in a Bayesian framework with smoothed Dirichlet estimation. The Bayesian approach provides conditional probability distributions for the multinomial parameters allowing one to take into account the prior information of the control experiment and providing a natural way to separate signal from noise, since it automatically furnishes Bayesian confidence intervals and thus avoids the drawbacks of preliminary error filtering. CONCLUSIONS: The methods described in this paper have been implemented as an integrated tool called Tanden (Tool for Analysis of Diversity in Viral Populations) and successfully tested on samples obtained from HIV-1 strain NL4-3 (group M, subtype B) cultivations on primary human cell cultures in many distinct viral propagation conditions. Tanden is written in C# (Microsoft), runs on the Windows operating system, and can be downloaded from: http://tanden.url.ph/.

HIV-1 Tropism Determines Different Mutation Profiles in Proviral DNA.

In order to establish new infections HIV-1 particles need to attach to receptors expressed on the cellular surface. HIV-1 particles interact with a cell membrane receptor known as CD4 and subsequently with another cell membrane molecule known as a co-receptor. Two major different co-receptors have been identified: C-C chemokine Receptor type 5 (CCR5) and C-X-C chemokine Receptor type 4 (CXCR4) Previous reports have demonstrated cellular modifications upon HIV-1 binding to its co-receptors including gene expression modulations. Here we investigated the effect of viral binding to either CCR5 or CXCR4 co-receptors on viral diversity after a single round of reverse transcription. CCR5 and CXCR4 pseudotyped viruses were used to infect non-stimulated and stimulated PBMCs and purified CD4 positive cells. We adopted the SOLiD methodology to sequence virtually the entire proviral DNA from all experimental infections. Infections with CCR5 and CXCR4 pseudotyped virus resulted in different patterns of genetic diversification. CCR5 virus infections produced extensive proviral diversity while in CXCR4 infections a more localized substitution process was observed. In addition, we present pioneering results of a recently developed method for the analysis of SOLiD generated sequencing data applicable to the study of viral quasi-species. Our findings demonstrate the feasibility of viral quasi-species evaluation by NGS methodologies. We presented for the first time strong evidence for a host cell driving mechanism acting on the HIV-1 genetic variability under the control of co-receptor stimulation. Additional investigations are needed to further clarify this question, which is relevant to viral diversification process and consequent disease progression.

High rates of human immunodeficiency virus type 1 mutational profiles by single-genome amplification after 48-hour propagation in peripheral blood mononuclear cells at different levels of cell activation.

Human immunodeficiency virus type 1 (HIV-1) genetic diversity is one of the most important features of HIV-1 infections and the result of error accumulation during reverse transcription and of high viral turnover. HIV-1 reverse transcription is influenced by factors such as the level of nucleotides and/or the cellular activation state. HIV-1 diversity was investigated after 48 h of viral propagation in peripheral blood mononuclear cells (PBMCs) obtained from healthy donors in three different cell culture conditions: (1) resting PBMCs, (2) simultaneous infection and PBMC activation, and (3) PBMC activation 72 h before infection. Cellular DNA was extracted and proviruses of each culture condition were amplified. Single-genome PCR clones were obtained and the protease and reverse transcriptase of the pol gene were sequenced. An elevated number of nucleotide substitutions in all three culture conditions were observed. In condition 1, the mutational rate observed ranged from 1.0 × 10(-3) to 2.1 × 10(-2), the genetic diversity was 0.6%, and hypermutation was observed in 7.1% of sequenced clones. In condition 2, the mutational rate ranged from 1.0 × 10(-3) to 1.0 × 10(-2), the genetic diversity was 0.8%, and hypermutation affected 6.7% of clones. In condition 3, the mutational rate ranged from 2.8 × 10(-3) to 1.1 × 10(-2), the genetic diversity was 1%, and 5.9% of clones were hypermutated. Substitutions occurred more frequently in some specific nucleotide stretches, and a common pattern for substitutions in all the different conditions was identified. There was a significant accumulation of mutations during the initial periods of in vitro HIV-1 propagation irrespective of culture conditions. The rapid accumulation of virus diversity might represent a viral strategy when colonizing new hosts. Complementary studies are necessary to allow for a better understanding of the initial periods of infection, which represent a crucial event related to disease progression.

Analysis of HIV-1 protease gene reveals frequent multiple infections followed by recombination among drug treated individuals living in São Paulo and Santos, Brazil.

The present study investigated the prevalence of HIV-1 multiple infections in a population composed by 47 patients under HAART failure and enrolled at the National DST/AIDS, Program, Ministry of Health, Brazil.Detection of multiple infections was done using a previously published RFLP assay for the HIV-1 protease gene, which is able of distinguishing between infections caused by a single or multiple HIV-1 subtypes. Samples with multiple infections were cloned, and sequence data submitted to phylogenetic analysis. We were able to identify 17 HIV-1 multiple infections out of 47 samples. Multiple infections were mostly composed by a mixture of recombinant viruses (94%), with only one case in which protease gene pure subtypes B and F were recovered. This is the first study that reports the prevalence of multiple infections and intersubtype recombinants in a population undergoing HAART in Brazil. Based on the data there was a steep increase of multiple infections after the introduction of the combined antiretroviral therapy in Brazil. Cases of multiple infections may be associated with HIV-1 genetic diversity through recombination allowing for the generation of viruses showing a combination of resistance mutations.

Analysis of the origin and evolutionary history of HIV-1 CRF28_BF and CRF29_BF reveals a decreasing prevalence in the AIDS epidemic of Brazil.

BACKGROUND: HIV-1 subtype B and subtype F are prevalent in the AIDS epidemic of Brazil. Recombinations between these subtypes have generated at least four BF circulating recombinant forms (CRFs). CRF28_BF and CRF29_BF are among the first two BF recombinants being identified in Brazil and they contributed significantly to the epidemic. However, the evolution and demographic histories of the CRFs are unclear. METHODOLOGY/PRINCIPAL FINDINGS: A collection of gag and pol sequences sampled within Brazil was screened for CRF28_BF-like and CRF29_BF-like recombination patterns. A Bayesian coalescent framework was employed to delineate the phylogenetic, divergence time and population dynamics of the virus having CRF28_BF-like and CRF29_BF-like genotype. These recombinants were phylogenetically related to each other and formed a well-supported monophyletic clade dated to 1988-1989. The effective number of infections by these recombinants grew exponentially over a five-year period after their emergence, but then decreased toward the present following a logistic model of population growth. The demographic pattern of both recombinants closely resembles those previously reported for CRF31_BC. CONCLUSIONS: We revealed that HIV-1 recombinants of the CRF28_BF/CRF29_BF clade are still circulating in the Brazilian population. These recombinants did not exhibit a strong founder effect and showed a decreasing prevalence in the AIDS epidemic of Brazil. Our data suggested that multiple URFs may also play a role in shaping the epidemic of recombinant BF HIV-1 in the region.