Despite a high current standard of care in antiretroviral therapy for HIV, multidrug-resistant strains continue to emerge, underscoring the need for additional novel mechanism inhibitors that will ...offer expanded therapeutic options in the clinic. We report a new class of small molecule antiretroviral compounds that directly target HIV-1 capsid (CA) via a novel mechanism of action. The compounds exhibit potent antiviral activity against HIV-1 laboratory strains, clinical isolates, and HIV-2, and inhibit both early and late events in the viral replication cycle. We present mechanistic studies indicating that these early and late activities result from the compound affecting viral uncoating and assembly, respectively. We show that amino acid substitutions in the N-terminal domain of HIV-1 CA are sufficient to confer resistance to this class of compounds, identifying CA as the target in infected cells. A high-resolution co-crystal structure of the compound bound to HIV-1 CA reveals a novel binding pocket in the N-terminal domain of the protein. Our data demonstrate that broad-spectrum antiviral activity can be achieved by targeting this new binding site and reveal HIV CA as a tractable drug target for HIV therapy.
The emergence of ZIKV infection has prompted a global effort to develop safe and effective vaccines. We engineered a lipid nanoparticle (LNP) encapsulated modified mRNA vaccine encoding wild-type or ...variant ZIKV structural genes and tested immunogenicity and protection in mice. Two doses of modified mRNA LNPs encoding prM-E genes that produced virus-like particles resulted in high neutralizing antibody titers (∼1/100,000) that protected against ZIKV infection and conferred sterilizing immunity. To offset a theoretical concern of ZIKV vaccines inducing antibodies that cross-react with the related dengue virus (DENV), we designed modified prM-E RNA encoding mutations destroying the conserved fusion-loop epitope in the E protein. This variant protected against ZIKV and diminished production of antibodies enhancing DENV infection in cells or mice. A modified mRNA vaccine can prevent ZIKV disease and be adapted to reduce the risk of sensitizing individuals to subsequent exposure to DENV, should this become a clinically relevant concern.
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•A modified mRNA vaccine encoding prM-E protects in 3 different mouse strains•Extraordinarily high titers of neutralizing antibodies (>1/100,000 EC50) are produced•Sterilizing immunity was achieved with a single prime-boost strategy•A fusion loop mutant vaccine reduced production of enhancing anti-DENV antibodies
A modified mRNA vaccine induces sterilizing immunity against Zika virus while minimizing the generation of cross-reactive antibodies that may enhance dengue infection.
Global climate change is expected to affect terrestrial ecosystems in a variety of ways. Some of the more well-studied effects include the biogeochemical feedbacks to the climate system that can ...either increase or decrease the atmospheric load of greenhouse gases such as carbon dioxide and nitrous oxide. Less well-studied are the effects of climate change on the linkages between soil and plant processes. Here, we report the effects of soil warming on these linkages observed in a large field manipulation of a deciduous forest in southern New England, USA, where soil was continuously warmed 5°C above ambient for 7 years. Over this period, we have observed significant changes to the nitrogen cycle that have the potential to affect tree species composition in the long term. Since the start of the experiment, we have documented a 45% average annual increase in net nitrogen mineralization and a three-fold increase in nitrification such that in years 5 through 7, 25% of the nitrogen mineralized is then nitrified. The warming-induced increase of available nitrogen resulted in increases in the foliar nitrogen content and the relative growth rate of trees in the warmed area.Acer rubrum (red maple) trees have responded the most after 7 years of warming, with the greatest increases in both foliar nitrogen content and relative growth rates. Our study suggests that considering species-specific responses to increases in nitrogen availability and changes in nitrogen form is important in predicting future forest composition and feedbacks to the climate system.
Exercise intolerance (EI) is the primary manifestation of chronic heart failure with preserved ejection fraction (HFpEF), the most common form of heart failure among older individuals. The recent ...recognition that HFpEF is likely a systemic, multiorgan disorder that shares characteristics with other common, difficult-to-treat, aging-related disorders suggests that novel insights may be gained from combining knowledge and concepts from aging and cardiovascular disease disciplines. This state-of-the-art review is based on the outcomes of a National Institute of Aging-sponsored working group meeting on aging and EI in HFpEF. We discuss aging-related and extracardiac contributors to EI in HFpEF and provide the rationale for a transdisciplinary, "gero-centric" approach to advance our understanding of EI in HFpEF and identify promising new therapeutic targets. We also provide a framework for prioritizing future research, including developing a uniform, comprehensive approach to phenotypic characterization of HFpEF, elucidating key geroscience targets for treatment, and conducting proof-of-concept trials to modify these targets.
Early steps of infection by HIV-1 involve entry of the viral core into cells, reverse transcription to form the linear viral DNA, and integration of that DNA into a chromosome of the host. The ...unintegrated DNA can also follow non-productive pathways, in which it is circularized by recombination between DNA long-terminal repeats (LTRs), circularized by ligation of the DNA ends or degraded. Here we report quantitative methods that monitor formation of reverse transcription products, two-LTR circles and integrated proviruses. The integration assay employs a novel quantitative form of Alu-PCR that should be generally applicable to studies of integrating viruses and gene transfer vectors.
Processing of the Gag precursor protein by the viral protease during particle release triggers virion maturation, an essential step in the virus replication cycle. The first-in-class HIV-1 maturation ...inhibitor dimethylsuccinyl betulinic acid PA-457 or bevirimat (BVM) blocks HIV-1 maturation by inhibiting the cleavage of the capsid-spacer peptide 1 (CA-SP1) intermediate to mature CA. A structurally distinct molecule, PF-46396, was recently reported to have a similar mode of action to that of BVM. Because of the structural dissimilarity between BVM and PF-46396, we hypothesized that the two compounds might interact differentially with the putative maturation inhibitor-binding pocket in Gag. To test this hypothesis, PF-46396 resistance was selected for in vitro. Resistance mutations were identified in three regions of Gag: around the CA-SP1 cleavage site where BVM resistance maps, at CA amino acid 201, and in the CA major homology region (MHR). The MHR mutants are profoundly PF-46396-dependent in Gag assembly and release and virus replication. The severe defect exhibited by the inhibitor-dependent MHR mutants in the absence of the compound is also corrected by a second-site compensatory change far downstream in SP1, suggesting structural and functional cross-talk between the HIV-1 CA MHR and SP1. When PF-46396 and BVM were both present in infected cells they exhibited mutually antagonistic behavior. Together, these results identify Gag residues that line the maturation inhibitor-binding pocket and suggest that BVM and PF-46396 interact differentially with this putative pocket. These findings provide novel insights into the structure-function relationship between the CA MHR and SP1, two domains of Gag that are critical to both assembly and maturation. The highly conserved nature of the MHR across all orthoretroviridae suggests that these findings will be broadly relevant to retroviral assembly. Finally, the results presented here provide a framework for increased structural understanding of HIV-1 maturation inhibitor activity.
Serum levels of miR-194 have been reported to predict prostate cancer recurrence after surgery, but its functional contributions to this disease have not been studied. Herein, it is demonstrated that ...miR-194 is a driver of prostate cancer metastasis. Prostate tissue levels of miR-194 were associated with disease aggressiveness and poor outcome. Ectopic delivery of miR-194 stimulated migration, invasion, and epithelial-mesenchymal transition in human prostate cancer cell lines, and stable overexpression of miR-194 enhanced metastasis of intravenous and intraprostatic tumor xenografts. Conversely, inhibition of miR-194 activity suppressed the invasive capacity of prostate cancer cell lines
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Mechanistic investigations identified the ubiquitin ligase suppressor of cytokine signaling 2 (SOCS2) as a direct, biologically relevant target of miR-194 in prostate cancer. Low levels of
correlated strongly with disease recurrence and metastasis in clinical specimens. SOCS2 downregulation recapitulated miR-194-driven metastatic phenotypes, whereas overexpression of a nontargetable SOCS2 reduced miR-194-stimulated invasion. Targeting of SOCS2 by miR-194 resulted in derepression of the oncogenic kinases FLT3 and JAK2, leading to enhanced ERK and STAT3 signaling. Pharmacologic inhibition of ERK and JAK/STAT pathways reversed miR-194-driven phenotypes. The GATA2 transcription factor was identified as an upstream regulator of miR-194, consistent with a strong concordance between GATA2 and miR-194 levels in clinical specimens. Overall, these results offer new insights into the molecular mechanisms of metastatic progression in prostate cancer.
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The realm of wildland fire science encompasses both wild and prescribed fires. Most of the research in the broader field has focused on wildfires, however, despite the prevalence of prescribed fires ...and demonstrated need for science to guide its application. We argue that prescribed fire science requires a fundamentally different approach to connecting related disciplines of physical, natural, and social sciences. We also posit that research aimed at questions relevant to prescribed fire will improve overall wildland fire science and stimulate the development of useful knowledge about managed wildfires. Because prescribed fires are increasingly promoted and applied for wildfire management and are intentionally ignited to meet policy and land manager objectives, a broader research agenda incorporating the unique features of prescribed fire is needed. We highlight the primary differences between prescribed fire science and wildfire science in the study of fuels, fire behavior, fire weather, fire effects, and fire social science. Wildfires managed for resource benefits (“managed wildfires”) offer a bridge for linking these science frameworks. A recognition of the unique science needs related to prescribed fire will be key to addressing the global challenge of managing wildland fire for long-term sustainability of natural resources.
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