HIV-1 Protease Research Articles

Comprehending the Structure, Dynamics, and Mechanism of Action of Drug-Resistant HIV Protease.

Since the emergence of the Human Immunodeficiency Virus (HIV) in the 1980s, strategies to combat HIV-AIDS are continuously evolving. Among the many tested targets to tackle this virus, its protease enzyme (PR) was proven to be an attractive option that brought about numerous research publications and ten FDA-approved drugs to inhibit the PR activity. However, the drug-induced mutations in the enzyme made these small molecule inhibitors ineffective with prolonged usage. The research on HIV PR, therefore, remains a thrust area even today. Through this review, we reiterate the importance of understanding the various structural and functional components of HIV PR in redesigning the structure-based small molecule inhibitors. We also discuss at length the currently available FDA-approved drugs and how these drug molecules induced mutations in the enzyme structure. We then recapitulate the reported mechanisms on how these drug-resistant variants remain sufficiently active to cleave the natural substrates. We end with the future scope covering the recently proposed strategies that show promise to deal with the mutations.

X-ray structures of HIV-1 protease

X-ray structures of HIV-1 protease

Mouse mammary tumor virus is implicated in severity of colitis and dysbiosis in the IL-10−/− mouse model of inflammatory bowel disease

BackgroundFollowing viral infection, genetically manipulated mice lacking immunoregulatory function may develop colitis and dysbiosis in a strain-specific fashion that serves as a model for inflammatory bowel disease (IBD). We found that one such model of spontaneous colitis, the interleukin (IL)-10 knockout (IL-10−/−) model derived from the SvEv mouse, had evidence of increased Mouse mammary tumor virus (MMTV) viral RNA expression compared to the SvEv wild type. MMTV is endemic in several mouse strains as an endogenously encoded Betaretrovirus that is passaged as an exogenous agent in breast milk. As MMTV requires a viral superantigen to replicate in the gut-associated lymphoid tissue prior to the development of systemic infection, we evaluated whether MMTV may contribute to the development of colitis in the IL-10−/− model.ResultsViral preparations extracted from IL-10−/− weanling stomachs revealed augmented MMTV load compared to the SvEv wild type. Illumina sequencing of the viral genome revealed that the two largest contigs shared 96.4–97.3% identity with the mtv-1 endogenous loci and the MMTV(HeJ) exogenous virus from the C3H mouse. The MMTV sag gene cloned from IL-10−/− spleen encoded the MTV-9 superantigen that preferentially activates T-cell receptor Vβ-12 subsets, which were expanded in the IL-10−/− versus the SvEv colon. Evidence of MMTV cellular immune responses to MMTV Gag peptides was observed in the IL-10−/− splenocytes with amplified interferon-γ production versus the SvEv wild type. To address the hypothesis that MMTV may contribute to colitis, we used HIV reverse transcriptase inhibitors, tenofovir and emtricitabine, and the HIV protease inhibitor, lopinavir boosted with ritonavir, for 12-week treatment versus placebo. The combination antiretroviral therapy with known activity against MMTV was associated with reduced colonic MMTV RNA and improved histological score in IL-10−/− mice, as well as diminished secretion of pro-inflammatory cytokines and modulation of the microbiome associated with colitis.ConclusionsThis study suggests that immunogenetically manipulated mice with deletion of IL-10 may have reduced capacity to contain MMTV infection in a mouse-strain-specific manner, and the antiviral inflammatory responses may contribute to the complexity of IBD with the development of colitis and dysbiosis.8hbTGJzMzAHuPYE9uy6yoBVideo

The effect of HIV protease gene mutations to protease inhibitor drugs resistance in Papua patients: In silico analysis

The use of phenotypic assay requires laborious work to culture HIV isolates to observe the phenotypic change of the virus in the presence of antiretroviral drugs. The genotypic approach may rely on the secondary data of documented mutations that are responsible for phenotypic alterations to antiretroviral-resistant HIV. HIV genomes were extracted from patients’ plasma, which was subsequently subjected to RT-PCR and Sanger sequencing. The obtained HIV genome sequencing data were analyzed for mutation detection. Three-dimensional (3D) structures of mutant HIV protease were constructed using FoldX software. The binding affinity of the mutant HIV protease with protease inhibitor drugs (Saquinavir, Ritonavir, Nelfinavir, Indinavir, and Lopinavir) was analyzed using AutoDock Vina. There were 90 patients involved in this study. The patients attended the Voluntary Counseling Test (VCT) of Mitra Masyarakat Hospital in Mimika, Papua, Indonesia. Among recruited subjects, the HIV genomes corresponding to the protease-encoded gene of 30 patients were successfully sequenced. There was only one patient (RSMM_70) infected with HIV harboring minor mutations (L10V, I15V, M36I, and R41K) in the protease-encoded gene that was not a new finding mutation. The 3D structure showed that the hydrophobicity and stability of mutant HIV protease were different from the wild genotype. Docking analysis showed decreasing binding affinity of the mutant HIV protease to the protease inhibitor drugs, which may lead to the alteration of inhibitory effectiveness. In silico docking, the analysis may provide an alternative approach to predict the effect of minor mutations in the HIV protease gene on the effectiveness of protease inhibitor drugs.

Stability and Mechanical Properties of Darunavir Isostructural Solvates: An Experimental and Computational Study

A search for suitable solid forms was an integral part of pharmaceutical manufacturing. In this study, nine isostructural solvates of darunavir (DLNW), an oral nonpeptidyl HIV-1 protease inhibitor, were prepared in different solvent systems (water [Shen, J. . CrystEngComm 2019, 1102], methanol, ethanol [Shen, J. CrystEngComm 2019, 1102], isopropanol, 1-propanol, ethyl acetate, acetone, N,N-dimethyl formamide, and dimethyl sulfoxide). The phase compositions of prepared samples were confirmed by single-crystal X-ray diffraction studies. The relationship between crystal structure and mechanical properties of each solvate was also investigated through the inspection of crystal structures, with a focus on hydrogen bonding interactions. We further compared the thermal stabilities and mechanical properties of different DLNW solvates, experimentally determined using thermal methods and nanoindentation, in combination with the simulation of topological analysis, energy framework, and core-valence bifurcation, respectively. The results showed that nine solvates were isostructural with varying proportions of solvent and different thermal stabilities because of the differences in solvent molecules. Darunavir dihydrate (DLNW-2H) showed the best compressibility and therefore could be regarded as a sensible choice for active pharmaceutical ingredients. A new solvent-free crystalline DLNW form was also obtained through the transformation of darunavir ethyl acetate solvate (DLNW-EAC), paving a feasible way to develop novel polymorphs, which were worthy of further research and attention in manufacturing.

PEGylated Liposomes Loaded with Carbamate Inhibitor ANP0903 Trigger Apoptosis by Enhancing ER Stress in HepG2 Cancer Cells

Liver cancer is one of the most common causes of cancer death worldwide. In recent years, substantial progress has been made in the development of systemic therapies, but there is still the need for new drugs and technologies that can increase the survival and quality of life of patients. The present investigation reports the development of a liposomal formulation of a carbamate molecule, reported as ANP0903, previously tested as an inhibitor of HIV-1 protease and now evaluated for its ability to induce cytotoxicity in hepatocellular carcinoma cell lines. PEGylated liposomes were prepared and characterized. Small, oligolamellar vesicles were produced, as demonstrated by light scattering results and TEM images. The physical stability of the vesicles in biological fluids was demonstrated in vitro, alongside the stability during storage. An enhanced cellular uptake was verified in HepG2 cells treated with liposomal ANP0903, resulting in a greater cytotoxicity. Several biological assays were performed to elucidate the molecular mechanisms explaining the proapoptotic effect of ANP0903. Our results allow us to hypothesize that the cytotoxic action in tumor cells is probably due to the inhibition of the proteasome, resulting in an increase in the amount of ubiquitinated proteins within the cells, which in turn triggers activation of autophagy and apoptosis processes, resulting in cell death. The proposed liposomal formulation represents a promising approach to deliver a novel antitumor agent to cancer cells and enhance its activity.

OPUS-Mut: Studying the Effect of Protein Mutation through Side-Chain Modeling.

Predicting the effect of protein mutation is crucial in many applications such as protein design, protein evolution, and genetic disease analysis. Structurally, mutation is basically the replacement of the side chain of a particular residue. Therefore, accurate side-chain modeling is useful in studying the effect of mutation. Here, we propose a computational method, namely, OPUS-Mut, which significantly outperforms other backbone-dependent side-chain modeling methods including our previous method OPUS-Rota4. We evaluate OPUS-Mut by four case studies on Myoglobin, p53, HIV-1 protease, and T4 lysozyme. The results show that the predicted structures of side chains of different mutants are consistent well with their experimentally determined results. In addition, when the residues with significant structural shifts upon the mutation are considered, it is found that the extent of the predicted structural shift of these affected residues can be correlated reasonably well with the functional changes of the mutant measured by experiments. OPUS-Mut can also help one to identify the harmful and benign mutations and thus may guide the construction of a protein with relatively low sequence homology but with a similar structure.

Understanding Drug Resistance of Wild-Type and L38HL Insertion Mutant of HIV-1 C Protease to Saquinavir.

Acquired immunodeficiency syndrome (AIDS) is one of the most challenging infectious diseases to treat on a global scale. Understanding the mechanisms underlying the development of drug resistance is necessary for novel therapeutics. HIV subtype C is known to harbor mutations at critical positions of HIV aspartic protease compared to HIV subtype B, which affects the binding affinity. Recently, a novel double-insertion mutation at codon 38 (L38HL) was characterized in HIV subtype C protease, whose effects on the interaction with protease inhibitors are hitherto unknown. In this study, the potential of L38HL double-insertion in HIV subtype C protease to induce a drug resistance phenotype towards the protease inhibitor, Saquinavir (SQV), was probed using various computational techniques, such as molecular dynamics simulations, binding free energy calculations, local conformational changes and principal component analysis. The results indicate that the L38HL mutation exhibits an increase in flexibility at the hinge and flap regions with a decrease in the binding affinity of SQV in comparison with wild-type HIV protease C. Further, we observed a wide opening at the binding site in the L38HL variant due to an alteration in flap dynamics, leading to a decrease in interactions with the binding site of the mutant protease. It is supported by an altered direction of motion of flap residues in the L38HL variant compared with the wild-type. These results provide deep insights into understanding the potential drug resistance phenotype in infected individuals.

From Capillary Electrophoresis to Deep Sequencing: An Improved HIV-1 Drug Resistance Assessment Solution Using In Vitro Diagnostic (IVD) Assays and Software.

Drug-resistance mutations were mostly detected using capillary electrophoresis sequencing, which does not detect minor variants with a frequency below 20%. Next-Generation Sequencing (NGS) can now detect additional mutations which can be useful for HIV-1 drug resistance interpretation. The objective of this study was to evaluate the performances of CE-IVD assays for HIV-1 drug-resistance assessment both for target-specific and whole-genome sequencing, using standardized end-to-end solution platforms. A total of 301 clinical samples were prepared, extracted, and amplified for the three HIV-1 genomic targets, Protease (PR), Reverse Transcriptase (RT), and Integrase (INT), using the CE-IVD DeepChek® Assays; and then 19 clinical samples, using the CE-IVD DeepChek® HIV Whole Genome Assay, were sequenced on the NGS iSeq100 and MiSeq (Illumina, San Diego, CA, USA). Sequences were compared to those obtained by capillary electrophoresis. Quality control for Molecular Diagnostics (QCMD) samples was added to validate the clinical accuracy of these in vitro diagnostics (IVDs). Nineteen clinical samples were then tested with the same sample collection, handling, and measurement procedure for evaluating the use of NGS for whole-genome HIV-1. Sequencing analyzer outputs were submitted to a downstream CE-IVD standalone software tailored for HIV-1 analysis and interpretation. The limits of range detection were 1000 to 106 cp/mL for the HIV-1 target-specific sequencing. The median coverage per sample for the three amplicons (PR/RT and INT) was 13,237 reads. High analytical reproducibility and repeatability were evidenced by a positive percent agreement of 100%. Duplicated samples in two distinct NGS runs were 100% homologous. NGS detected all the mutations found by capillary electrophoresis and identified additional resistance variants. A perfect accuracy score with the QCMD panel detection of drug-resistance mutations was obtained. This study is the first evaluation of the DeepChek® Assays for targets specific (PR/RT and INT) and whole genome. A cutoff of 3% allowed for a better characterization of the viral population by identifying additional resistance mutations and improving the HIV-1 drug-resistance interpretation. The use of whole-genome sequencing is an additional and complementary tool to detect mutations in newly infected untreated patients and heavily experienced patients, both with higher HIV-1 viral-load profiles, to offer new insight and treatment strategies, especially using the new HIV-1 capsid/maturation inhibitors and to assess the potential clinical impact of mutations in the HIV-1 genome outside of the usual HIV-1 targets (RT/PR and INT).

Environmentally benign synthesis of unsymmetrical ureas and their evaluation as potential HIV-1 protease inhibitors via a computational approach.

The present work reports the cost-effective, high yielding and environmentally acceptable preparation of unsymmetrical ureas from thiocarbamate salts using sodium percarbonate as an oxidant. Efficacy of the unsymmetrical ureas as potential human immune deficiency virus (HIV-1) protease inhibitors has been evaluated via in silico approach. The results revealed interactions of the urea compounds at the active site of the enzyme with favorable binding affinities causing possible mutations hindering the functioning of the enzyme. Further computational assessment of IC50 using known references satisfactorily authenticated the inhibitory action of the selected compounds against HIV-1 protease. Added to the easy synthesis of the ureas following an environmentally benign protocol, this work may be a valuable addition to the ongoing search for drugs with better efficacy profiles and reduced toxicity against HIV.

HIV Drug Resistance in Adults Initiating or Reinitiating Antiretroviral Therapy in Uruguay-Results of a Nationally Representative Survey, 2018-2019.

The first nationally representative cross-sectional HIV drug resistance (HIVDR) survey was conducted in Uruguay in 2018-2019 among adults diagnosed with HIV and initiating or reinitiating antiretroviral therapy (ART). Protease, reverse transcriptase, and integrase genes of HIV-1 were sequenced. A total of 206 participants were enrolled in the survey; 63.2% were men, 85.7% were >25 years of age, and 35.6% reported previous exposure to antiretroviral (ARV) drugs. The prevalence of HIVDR to efavirenz or nevirapine was significantly higher (OR: 1.82, p < 0.001) in adults with previous ARV drug exposure (20.3%, 95% CI: 18.7-22.0%) compared to adults without previous ARV drug exposure (12.3%, 11.0-13.8%). HIVDR to any nucleoside reverse transcriptase inhibitors was 10.3% (9.4-11.2%). HIVDR to ritonavir-boosted protease inhibitors was 1.5% (1.1-2.1%); resistance to ritonavir-boosted darunavir was 0.9% (0.4-2.1%) among adults without previous ARV drug exposure and it was not observed among adults with previous ARV drug exposure. Resistance to integrase inhibitors was 12.7% (11.7-13.8%), yet HIVDR to dolutegravir, bictegravir, and cabotegravir was not observed. The high level (>10%) of HIVDR to efavirenz highlights the need to accelerate the transition to the WHO-recommended dolutegravir-based ART. Access to dolutegravir-based ART should be prioritised for people reporting previous ARV drug exposure.

Affordable drug resistance genotyping of HIV-1 reverse transcriptase, protease and integrase genes, for resource limited settings

BackgroundAs use of dolutegravir (DTG) becomes more common in resource limited settings (RLS), the demand for integrase resistance testing is increasing. Affordable methods for genotyping all relevant HIV-1 pol genes (i.e., protease (PR), reverse transcriptase (RT) and integrase (IN)) are required to guide choice of future antiretroviral therapy (ART). We designed an in-house HIV-1 drug resistance (HIVDR) genotyping method that is affordable and suitable for use in RLS.MethodsWe obtained remnant plasma samples from CAPRISA 103 study and amplified HIV-1 PR, RT and IN genes, using an innovative PCR assay. We validated the assay using remnant plasma samples from an external quality assessment (EQA) programme. We genotyped samples by Sanger sequencing and assessed HIVDR mutations using the Stanford HIV drug resistance database. We compared drug resistance mutations with previous genotypes and calculated method cost-estimates.ResultsFrom 96 samples processed, we obtained sequence data for 78 (81%), of which 75 (96%) had a least one HIVDR mutation, with no major-IN mutations observed. Only one sample had an E157Q INSTI-accessory mutation. When compared to previous genotypes, 18/78 (23%) had at least one discordant mutation, but only 2/78 (3%) resulted in different phenotypic predictions that could affect choice of subsequent regimen. All CAPRISA 103 study sequences were HIV-1C as confirmed by phylogenetic analysis. Of the 7 EQA samples, 4 were HIV-1C, 2 were HIV-1D, and 1 was HIV-1A. Genotypic resistance data generated using the IDR method were 100% concordant with EQA panel results. Overall genotyping cost per sample was estimated at ~ US$43–$US49, with a processing time of ~ 2 working days.ConclusionsWe successfully designed an in-house HIVDR method that is suitable for genotyping HIV-1 PR, RT and IN genes, at an affordable cost and shorter turnaround time. This HIVDR genotyping method accommodates changes in ART regimens and will help to guide HIV-1 treatment decisions in RLS.

In Vitro Anti-HIV-1 Activity of Chitosan Oligomers N-Conjugated with Asparagine and Glutamine.

Chitosan oligomers (COS) are polysaccharides obtained by the hydrolyzation of chitosan. They are water-soluble, biodegradable, and have a wide range of beneficial properties for human health. Studies have shown that COS and its derivatives possess antitumor, antibacterial, antifungal, and antiviral activities. The goal of the current study was to investigate the anti-human immunodeficiency virus-1 (HIV-1) potential of amino acid-conjugated COS compared to COS itself. The HIV-1 inhibitory effects of asparagine-conjugated (COS-N) and glutamine-conjugated (COS-Q) COS were evaluated by their ability to protect C8166 CD4+ human T cell lines from HIV-1 infection and infection-mediated death. The results show that the presence of COS-N and COS-Q was able to prevent cells from HIV-1-induced lysis. Additionally, p24 viral protein production was observed to be suppressed in COS conjugate-treated cells compared to COS-treated and untreated groups. However, the protective effect of COS conjugates diminished by delayed treatment indicated an early stage inhibitory effect. COS-N and COS-Q did not show any inhibitory effect on the activities of HIV-1 reverse transcriptase and protease enzyme. The results suggest that COS-N and COS-Q possess an HIV-1 entry inhibition activity compared to COS and further studies to develop different peptide and amino acid conjugates containing N and Q amino acids might yield more effective compounds to battle HIV-1 infection.

HIV-1 Gag Binds the Multi-Aminoacyl-tRNA Synthetase Complex via the EPRS Subunit.

Host factor tRNAs facilitate the replication of retroviruses such as human immunodeficiency virus type 1 (HIV-1). HIV-1 uses human tRNALys3 as the primer for reverse transcription, and the assembly of HIV-1 structural protein Gag at the plasma membrane (PM) is regulated by matrix (MA) domain-tRNA interactions. A large, dynamic multi-aminoacyl-tRNA synthetase complex (MSC) exists in the cytosol and consists of eight aminoacyl-tRNA synthetases (ARSs) and three other cellular proteins. Proteomic studies to identify HIV-host interactions have identified the MSC as part of the HIV-1 Gag and MA interactomes. Here, we confirmed that the MA domain of HIV-1 Gag forms a stable complex with the MSC, mapped the primary interaction site to the linker domain of bi-functional human glutamyl-prolyl-tRNA synthetase (EPRS), and showed that the MA-EPRS interaction was RNA dependent. MA mutations that significantly reduced the EPRS interaction reduced viral infectivity and mapped to MA residues that also interact with phosphatidylinositol-(4,5)-bisphosphate. Overexpression of EPRS or EPRS fragments did not affect susceptibility to HIV-1 infection, and knockdown of EPRS reduced both a control reporter gene and HIV-1 protein translation. EPRS knockdown resulted in decreased progeny virion production, but the decrease could not be attributed to selective effects on virus gene expression, and the specific infectivity of the virions remained unchanged. While the precise function of the Gag-EPRS interaction remains uncertain, we discuss possible effects of the interaction on either virus or host activities.

Evaluation of darunavir-derived HIV-1 protease inhibitors incorporating P2′ amide-derivatives: Synthesis, biological evaluation and structural studies

We report here the synthesis and biological evaluation of darunavir derived HIV-1 protease inhibitors and their functional effect on enzyme inhibition and antiviral activity in MT-2 cell lines. The P2′ 4-amino functionality was modified to make a number of amide derivatives to interact with residues in the S2′ subsite of the HIV-1 protease active site. Several compounds exhibited picomolar enzyme inhibitory and low nanomolar antiviral activity. The X-ray crystal structure of the chloroacetate derivative bound to HIV-1 protease was determined. Interestingly, the active chloroacetate group converted to the acetate functionality during X-ray exposure. The structure revealed that the P2′ carboxamide functionality makes enhanced hydrogen bonding interactions with the backbone atoms in the S2′-subsite.

Exact reaction coordinates for functional protein dynamics: Flap opening in HIV-1 protease.

The primary goal of protein science is to understand how proteins function, which requires understanding the functional dynamics responsible for transitions between different functional structures of a protein. A central concept is the exact reaction coordinates that can determine the value of committor for any protein configuration, which provide optimal characterization of functional dynamics. Despite intensive efforts, identifying exact reaction coordinates in complex molecules remains a formidable challenge. Using the recently developed generalized work functional, we report the discovery of the exact reaction coordinates for an important functional process--the flap opening of HIV-1 protease. Our results show that this process has six reaction coordinates, each one is a linear combination of ∼240 backbone dihedrals, providing exact definition of collectivity and cooperativity in functional dynamics of proteins. Applying bias potential along each reaction coordinate can accelerate flap opening by 103 to 104 folds. The success in identifying the reaction coordinates of a protein with 198 residues represents a significant progress beyond that of the alanine dipeptide, currently the only other complex molecule for which the exact reaction coordinates for its conformational changes are known. Our results suggest that the generalized work functional might be the fundamental mechanical operator that controls protein dynamics.

Bending membranes along distinct pathways of protein assembly.

Membrane remodeling is almost universally dependent on the work of self-assembled proteins. In viral budding, protein coat components can exploit distinct mechanisms to drive bending of the membrane from its preferred, relatively flat state. During HIV-1 infection, the retroviral Gag proteins can work to either scaffold the membrane or locally induce changes in curvature through insertion. While both mechanisms can operate simultaneously, the scaffolding will be dependent on assembly of higher-order Gag lattices. The extent to which the protein coat assembly precedes recruitment to the membrane will thus impact both membrane bending and further assembly, thereby tuning successful budding out of the cell. In HIV-1 infected cells, the arrival of Gag to the membrane may proceed via monomers or larger oligomers. We construct models of HIV-1 Gag lattice assembly using structure-resolved reaction-diffusion that allow us to quantify mechanisms of assembly in solution and on the membrane. Using a continuum membrane model, we can then couple distinct assembly paths to the corresponding energetic cost of membrane budding. We can further quantify how mutations to weaken either membrane bending mechanism would impair proper budding. Finally, we discuss when the stability and kinetics of the Gag lattice contacts can support lattice remodeling on the budded virion, which is critical for viral maturation.

Theory of HIV-1 RNA genome selection.

It is not understood how the HIV-1 retrovirus selects it genomic RNA (gRNA) for packaging into virions from among the multitude of cellular RNA molecules in the cytoplasm of infected cells. Under in-vitro conditions, the Gag proteins of HIV-1 have only a very weak specific binding affinity for the RNA Ψ sequence, which has been shown to be the key recognition label of genomic RNA. In addition, the cellular gRNA concentration is very low yet HIV packages gRNA with high fidelity. We present a numerical model for kinetic HIV-1 gRNA selection that is based on fusion of precursor buds followed by gRNA dimerization.

Role of gRNA binding in HIV-1 Gag assembly process.

Assembly of human immunodeficiency virus type 1 (HIV-1) is a multi-step process that occurs at the host cell plasma membrane and is driven by a viral structural protein, Gag. Newly synthesized cytosolic Gag particles are targeted to the inner leaflet of the plasma membrane and membrane-bound Gag polyproteins interact with each other to form higher order multimers. Gag polyprotein is composed of multiple structured domains connected by flexible linkers. N-myristoylated matrix (MA) domain mediates membrane binding process, capsid (CA) and nucleocapsid (NC) domains play vital roles in Gag multimerization process. Interactions of gRNA with the zinc finger motifs of the NC domain facilitate gRNA packaging into virions. To investigate the effect of Gag-gRNA binding on the different multimerization states, we have performed all-atom molecular dynamics simulations of full-length Gag multimers (hexamer and hexamer-of-trimers) bound to an asymmetric membrane. MA domain multimerizes as a hexamer of trimers whereas cryo-ET data shows that CA domains are organized as hexameric lattice. The multidomain correlation of Gag polyprotein as well as the effect of multimerization of one domain to the dynamics of others are still not clear. Here we aim to gain atomic-level characterization of the inter and intra-protein interactions between different structural domains of Gag polyprotein in the presence/absence of the effective rigidity of NC domain, associated with gRNA binding. In the hexamer-of-trimers, the rigidity of NC domain is observed to modify the structure and dynamics of Gag monomers, resulting in a different binding surface for cytosolic Gag protein. In case of membrane-bound Gag hexamer, gRNA binding alters the dynamics of MA-CA linker domains, and we observe a signature of PIP2 and cholesterol enrichment in the membrane that can modify membrane binding affinity for Gag hexamer and facilitate recruitment of cytosolic Gag protein.

The Combination of an mRNA Immunogen, a TLR7 Agonist and a PD1 Blocking Agent Enhances In-Vitro HIV T-Cell Immune Responses.

The development of new strategies to achieve a functional cure for HIV remains a priority. We tested a novel HIV therapeutic vaccine using unmodified mRNA (TMEP-B) and mRNA modified by 1-methyl-3'-pseudouridylyl (TMEP-Bmod) expressing both a multiepitopic sequences from Gag, Pol, and Nef proteins, including different CD4 and CD8 T-cell epitopes functionally associated with HIV control in transfected monocyte-derived dendritic cells (MDDCs) obtained from HIV infected patients. In vitro assays were used to test the mRNAs alone and in combination with immunomodulator agents, such as the TLR-7 agonist Vesatolimod and the PD-1 antagonist Nivolumab to try to improve HIV-specific cellular immune responses. Combining the mRNAs with the immunomodulators enhanced HIV-specific T-cell responses, together with the secretion of IFNγ, IP10, MIP-1α, and MIP-1β, which are fundamental mediators of viral control. Our data suggest that the mRNA vaccine prototypes TMEP-B and TMEP-Bmod, when combined with Vesatolimod and/or Nivolumab, could achieve functional cure for patients with HIV.