Project description:Here we investigated whether a combination of cell-free infection and cell-to-cell spread confers a selective advantage in the evolution of resistance to an inhibitor relative to cell-to-cell spread alone due to the stronger selection pressure against drug sensitive virus. We propagated HIV infection using coculture of infected with uninfected cells in the face of the reverse transcriptase inhibitor efavirenz (EFV), and compared the effect on drug resistance evolution of including one cycle of cell-free infection. In the presence of a single cell-free infection step, we obtained earlier evolution of resistance to EFV. When we increased selective pressure by adding emtricitabine (FTC as a second drug, infection with the cell-free step evolved multidrug resistance and was able to replicate, while infection without a cell-free step failed to evolve multidrug resistance. In conclusion, our results suggest that, HIV cell-to-cell spread has a decreased capacity to rapidly evolve resistance to inhibitors, which is conferred by cell-free infection.
Project description:We invesitgated cellular pathways required for HIV-1 activation using HIV-1-suppressing agents. Despite effective antiretroviral therapy, HIV-1-nfected cells continue to produce viral antigens and induce chronic immune exhaustion. Using a novel dual reporter system and a high-throughput drug screen, we identified FDA-approved drugs which can suppress HIV-1 reactivation in both cell line models and CD4+ T cells from virally suppressed, HIV-1-infected individuals. We identified 11 cellular pathways required for HIV-1 reactivation as druggable targets. Using differential expression analysis, gene set enrichment analysis and exon-intron landscape analysis, we examined the impact of drug treatment on the cellular environment at a genome-wide level.
Project description:We sought to determine how gene expression changes during the first two years of HIV-1 infection among participants from HIV-1 serodiscordant couple cohorts from sub-Saharan Africa. This study included whole blood samples from 26 participants who did not have HIV-1 at study enrollment, had a steady sexual relationship with a partner with HIV-1 and acquired HIV-1 during follow-up. Most participants had samples from before and after infection.
Project description:The goal of this study was to determine how an HIV quasispecies is maintained in the face of selection. We deep sequenced the HIV provirus from cell populations as well as single cells at different time points from in vitro evolution experiments and found that when a less fit and more fit infect the same cell, they share components (complmentation) and therefore allow the less fit to perpetuate. We reproduced a quasispecies to an HIV reverse transcriptase inhibitor. The drug resistant genotype never completely supplanted the drug sensitive genotype, which stabilized at about 20% of viral sequences. Single-cell sequencing showed that resistant genotype frequency plateaued when cells were co-infected with sensitive and resistant genotypes, suggesting a sharing of viral proteins in co-infected cells (complementation), masking genotypic differences. To test if complementation can confer phenotypic drug resistance, we co-transfected fluorescently labelled molecular clones of sensitive and resistant HIV and observed drug resistance in genotypically sensitive virus from co-transfected cells. Resistant virus preferentially co-infected cells with drug sensitive HIV, explaining initiation of co-infections. Modelling showed that a stable quasispecies could form at the experimental multiplicities of infection. Conclusions: Complementation can lead to a quasispecies in infection environments where multiple infections per cell are common
Project description:The response of human immunodeficiency virus type 1 (HIV-1) quasispecies to antiretroviral therapy is influenced by the ensemble of mutants that composes the evolving population. Low-abundance subpopulations within HIV-1 quasispecies may determine the viral response to the administered drug combinations. However, routine sequencing assays available to clinical laboratories do not recognize HIV-1 minority variants representing less than 25% of the population. Although several alternative and more sensitive genotyping techniques have been developed, including next-generation sequencing (NGS) methods, they are usually very time consuming, expensive and require highly trained personnel, thus becoming unrealistic approaches in daily clinical practice. Here we describe the development and testing of a HIV-1 genotyping DNA microarray that detects and quantifies, in majority and minority viral subpopulations, relevant mutations and amino acid insertions in 42 codons of the pol gene associated with resistance and multidrug resistance to protease (PR) and reverse transcriptase (RT) inhibitors. A customized bioinformatics protocol has been implemented to analyze the microarray hybridization data by including a new normalization procedure and a stepwise filtering algorithm which resulted in the highly accurate (96.33%) detection of positive/negative signals. This microarray has been tested with 57 subtype B HIV-1 clinical samples extracted from multi-treated patients, showing an overall identification of 95.53% and 89.24% of the queried PR and RT codons, respectively, and enough sensitivity to detect minority subpopulations representing as low as 5-10% of the total quasispecies. Such a genotyping platform represents an efficient diagnostic and prognostic tool useful to personalize antiviral treatments in clinical practice.
Project description:Simian immunodeficiency viruses infecting sooty mangabeys (SIVsmm) have been transmitted to humans on multiple occasions, giving rise to human immunodeficiency virus type 2 (HIV-2) groups A to I. However, only groups A and B spread significantly in humans causing an epidemic in West Africa. The reasons for this are poorly understood. Here, we show that genetically diverse SIVsmm strains efficiently infect primary human T cells. However, they are highly sensitive to type I IFN, indicating that interferon-stimulated genes (ISGs) pose a barrier to the successful spread of SIVsmm in humans. One well-known ISG is the zinc finger antiviral protein (ZAP), which specifically targets CpG dinucleotides in viral RNAs. To evade ZAP restriction, many viruses, including HIV-1, suppress their CpG content. Unexpectedly, we found that HIV-2 is less sensitive to restriction by ZAP than HIV-1 and SIVsmm despite significantly higher CpG content. Analyses of chimeric HIV-2/SIVsmm constructs, together with binding site mapping using eCLIP, revealed that the determinants of ZAP resistance map to the U3 region of the 3’ LTR that overlaps with the nef gene. Our results indicate that ZAP poses a barrier to the efficient spread of SIVsmm in humans and that epidemic HIV-2 evolved a unique mechanism to evade it.