Ligand polyvalency is a powerful modulator of protein-receptor interactions. Host-pathogen infection interactions are often mediated by glycan ligand-protein interactions, yet its interrogation with ...very high copy number ligands has been limited to heterogenous systems. Here we report that through the use of nested layers of multivalency we are able to assemble the most highly valent glycodendrimeric constructs yet seen (bearing up to 1,620 glycans). These constructs are pure and well-defined single entities that at diameters of up to 32 nm are capable of mimicking pathogens both in size and in their highly glycosylated surfaces. Through this mimicry these glyco-dendri-protein-nano-particles are capable of blocking (at picomolar concentrations) a model of the infection of T-lymphocytes and human dendritic cells by Ebola virus. The high associated polyvalency effects (β>10(6), β/N ~10(2)-10(3)) displayed on an unprecedented surface area by precise clusters suggest a general strategy for modulation of such interactions.
Water-soluble glycofullerenes based on a hexakis-adduct of 60fullerene with an octahedral addition pattern are very attractive compounds providing a spherical presentation of carbohydrates. These ...tools have been recently described and they have been used to interact with lectins in a multivalent manner. Here, we present the use of these glycofullerenes, including new members with 36 mannoses, as compounds able to inhibit a DC-SIGN-dependent cell infection by pseudotyped viral particles. The results obtained in these experiments demonstrate for the first time that these glycoconjugates are adequate to inhibit efficiently an infection process, and therefore, they can be considered as very promising and interesting tools to interfere in biological events where lectins such as DC-SIGN are involved.
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•Retroviral RTs have a strong strand displacement activity with RNA and DNA templates.•In HIV-1 RT, RNase H inactivating mutations reduce its RNA-dependent strand displacement ...activity.•RNase H active site inhibitors produce similar effects in WT RT-catalyzed DNA synthesis reactions.•Coumarin-based DNA pol/RNase H dual agents were the most effective strand displacement inhibitors.•Reported findings are relevant for antiretroviral drug design and transcriptomics technologies.
In retroviruses, strand displacement DNA-dependent DNA polymerization catalyzed by the viral reverse transcriptase (RT) is required to synthesize double-stranded proviral DNA. In addition, strand displacement during RNA-dependent DNA synthesis is critical to generate high-quality cDNA for use in molecular biology and biotechnology. In this work, we show that the loss of RNase H activity due to inactivating mutations in HIV-1 RT (e.g. D443N or E478Q) has no significant effect on strand displacement while copying DNA templates, but has a large impact on DNA polymerization in reactions carried out with RNA templates. Similar effects were observed with β-thujaplicinol and other RNase H active site inhibitors, including compounds with dual activity (i.e., characterized also as inhibitors of HIV-1 integrase and/or the RT DNA polymerase). Among them, dual inhibitors of HIV-1 RT DNA polymerase/RNase H activities, containing a 7-hydroxy-6-nitro-2H-chromen-2-one pharmacophore were found to be very potent and effective strand displacement inhibitors in RNA-dependent DNA polymerization reactions. These findings might be helpful in the development of transcriptomics technologies to obtain more uniform read coverages when copying long RNAs and for the construction of more representative libraries avoiding biases towards 5′ and 3′ ends, while providing valuable information for the development of novel antiretroviral agents.
Convalescent Plasma for Ebola Virus Disease Arribas, Jose R; Luczkowiak, Joanna; Delgado, Rafael
The New England journal of medicine,
06/2016, Letnik:
374, Številka:
25
Journal Article
SWCNTs, MWCNTs, and SWCNHs have been employed as virus-mimicking nanocarbon platforms for the multivalent presentation of carbohydrates in an artificial Ebola virus infection model assay. These ...carbon nanoforms have been chemically modified by the covalent attachment of glycodendrons and glycofullerenes using the CuAAC “click chemistry” approach. This modification dramatically increases the water solubility of these structurally different nanocarbons. Their efficiency in blocking DC-SIGN-mediated viral infection by an artificial Ebola virus has been tested in a cellular experimental assay, finding that glycoconjugates based on MWCNTs functionalized with glycofullerenes are potent inhibitors of viral infection.
Glycan–protein interactions control numerous biological events from cell–cell recognition and signaling to pathogen host cell attachment for infections. To infect cells, some viruses bind to immune ...cells with the help of DC-SIGN (dendritic cell DC-specific ICAM3-grabbing nonintegrin) C-type lectin expressed on dendritic and macrophage cell membranes, via their envelope protein. Prevention of this infectious interaction is a serious therapeutic option. Here, we describe the synthesis of the first water-soluble tetravalent fucocluster pseudopeptide-based 1,3-alternate thiacalixarenes as viral antigen mimics designed for the inhibition of DC-SIGN, to prevent viral particle uptake. Their preparation exploits straightforward convergent strategies involving one-pot Ugi four-component (Ugi-4CR) and azido-alkyne click chemistry reactions as key steps. Surface plasmon resonance showed strong inhibition of DC-SIGN interaction properties by tetravalent ligands designed with high relative potencies and β avidity factors. All ligands block DC-SIGN active sites at nanomolar IC50 preventing cis-cell infection by Ebola viral particles pseudotyped with EBOV glycoprotein (Zaire species of Ebola virus) on Jurkat cells that express DC-SIGN. In addition, we observed strong inhibition of DC-SIGN/human cytomegalovirus (HCMV)-gB recombinant glycoprotein interaction. This finding opens the way to the simple development of new models of water-soluble glycocluster-based thia-calixarenes with wide-ranging antimicrobial activities.
We have measured the humoral response to messenger RNA (mRNA) vaccines in COVID‐19 naïve and convalescent individuals. Third doses of mRNA COVID‐19 vaccines induced a significant increase in potency ...and breadth of neutralization against SARS‐CoV‐2 variants of concern (VoC) including Omicron subvariants BA.1, BA.2, and BA.2.12.1, that were cross‐neutralized at comparable levels and less for BA.4/5. This booster effect was especially important in naïve individuals that only after the third dose achieved a level that was comparable with that of vaccinated COVID‐19 convalescents except for BA.4/5. Avidity of RBD‐binding antibodies was also significantly increased in naïve individuals after the third dose, indicating an association between affinity maturation and cross neutralization of VoC. These results suggest that at least three antigenic stimuli by infection or vaccination with ancestral SARS‐CoV‐2 sequences are required to induce high avidity cross‐neutralizing antibodies. Nevertheless, the circulation of new subvariants such as BA.4/5 with partial resistance to neutralization will have to be closely monitored and eventually consider for future vaccine developments.
In addition to a variety of viral-glycoprotein receptors (e.g., heparan sulfate, Niemann–Pick C1, etc.), dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), from ...the C-type lectin receptor family, plays one of the most important pathogenic functions for a wide range of viruses (e.g., Ebola, human cytomegalovirus (HCMV), HIV-1, severe acute respiratory syndrome coronavirus 2, etc.) that invade host cells before replication; thus, its inhibition represents a relevant extracellular antiviral therapy. We report two novel p-tBu-calixarene glycoclusters 1 and 2, bearing tetrahydroxamic acid groups, which exhibit micromolar inhibition of soluble DC-SIGN binding and provide nanomolar IC50 inhibition of both DC-SIGN-dependent Jurkat cis-cell infection by viral particle pseudotyped with Ebola virus glycoprotein and the HCMV-gB-recombinant glycoprotein interaction with monocyte-derived dendritic cells expressing DC-SIGN. A unique cooperative involvement of sugar, linker, and calixarene core is likely behind the strong avidity of DC-SIGN for these low-valent systems. We claim herein new promising candidates for the rational development of a large spectrum of antiviral therapeutics.
Currently, the majority of the population has been vaccinated against COVID‐19 and/or has experienced SARS‐CoV‐2 infection either before or after vaccination. The immunological response to repeated ...episodes of infections is not completely clear. We measured SARS‐CoV‐2 specific neutralization titers by a pseudovirus assay after BA.1 infection and RBD‐specific immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) in a cohort of COVID‐19 uninfected and triple vaccinated individuals (breakthrough infection group, BTI) as compared with those previously infected by SARS‐CoV‐2 (reinfection group, REI) who underwent identical vaccination schedule. SARS‐CoV‐2 specific neutralizing response after BA.1 infection was significantly higher in the BTI group as compared with the REI. Furthermore, neutralization titers in REI were not significant different from convalescent non reinfected controls. RBD‐specific IgG and IgA, but not IgM, were also significantly higher in BTI as compared with REI. Our results show that the first episode of SARS‐CoV‐2 infection induces a significant increase in neutralizing titers in triple vaccinated individuals and that previous SARS‐CoV‐2 infection compromise significantly the neutralization response induced by reinfection, even by divergent SARS‐CoV‐2 variants and at least up to 2 years postinfection, suggesting a fundamental limitation in inducing effective booster through the intranasal route in previously infected individuals.
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