Alexander A. Chinarev

Polymeric inhibitor of influenza virus attachment protects mice from experimental influenza infection.

Synthetic sialic acid-containing macromolecules inhibit influenza virus attachment to target cells and suppress the virus-mediated hemagglutination and neutralize virus infectivity in cell culture. To test the protective effects of attachment inhibitors in vivo, mice were infected with mouse-adapted influenza virus A/Aichi/2/68 (H3N2) and treated with synthetic polyacrylamide-based sialylglycopolymer PAA-YDS bearing moieties of (Neu5Acalpha2-6Galbeta1-4GlcNAcbeta1-2Manalpha1)2-3,6Manbeta1-4GlcNAcbeta1-4GlcNAc. Single intranasal inoculations with PAA-YDS 30 min before or 10 min after infection increased the survival of mice (P<0.01). Multiple treatments with aerosolized PAA-YDS on days 2-5 post infection also increased survival (P<0.01), alleviated disease symptoms, and decreased lesions in the mouse lungs. These data suggest that synthetic polyvalent inhibitors of virus attachment can be used for prevention and treatment of influenza.

Polyglycine II Nanosheets: Supramolecular Antivirals?

Tetraantennary peptides [glycinen‐NHCH2]4C can form stable noncovalent structures by self‐assembly through intermolecular hydrogen bonding. The oligopeptide chains assemble as polyglycine II to yield submicron‐sized, flat, one‐molecule‐thick sheets. Attachment of α‐N‐acetylneuraminic acid (Neu5Acα) to the terminal glycine residues gives rise to water‐soluble assembled glycopeptides that are able to bind influenza virus multivalently and inhibit adhesion of the virus to cells 103‐fold more effectively than a monomeric glycoside of Neu5Acα. Another antiviral strategy based on virus‐promoted assembly of the glycopeptides was also demonstrated. Consequently, the self‐assembly principle offers new perspectives on the design of multivalent antivirals.

Multimeric glycotherapeutics: New paradigm

The general principle of anti-adhesion therapy is the inhibition of microorganism adhesion to the host cell with the help of a soluble receptor analog. Despite an evident attractiveness of the concept and its long existence, the therapeutics of the ‘post-antibiotic era’ have not yet appeared. This can be explained by the contradictoriness of requirements for anti-adhesion drugs: to be efficient a drug must be multivalent, i.e. large molecule, but to obtain FDA approval it should be a small molecule. A way to overcome this contradiction is self-assembly of glycopeptides. The carbohydrate part of glycopeptide is responsible for binding with the lectin of microorganisms, whereas a simple peptide part is responsible for an association to the so-called tectomers. Depending on the structure, tectomers are formed either spontaneously or upon promotion of a microorganism. In particular, sialopeptide, which is capable of converting to a tectomer only in the presence of the influenza virus, has been obtained. Thus, the new strategy of anti-adhesion therapy can be formulated as follows: (1) identification of oligosaccharide-receptor for a particular virus (bacteria); (2) optimization of the peptide part; (3) conventional trials. The expected advantages of this strategy are the following: (i) no polymer; (ii) a virion completely covered with a tectomer, i.e. blocking is both complete and irreversible; (iii) rapid and rational lead identification and optimization; (iv) minimum side effects; (v) potential for microorganism resistance to natural receptor is lower than in the case of mimetics. Published in 2004.

Simple stereoselective synthesis of α2-6 sialooligosaccharides

The sialylation approach reported by A. Khorlin et. al 30 years ago has been modified into a highly practical procedure for stereoselective α2-6 sialylation of galactopyranose 4,6-diols.

Comparison of printed glycan array, suspension array and ELISA in the detection of human anti-glycan antibodies

Anti-glycan antibodies represent a vast and yet insufficiently investigated subpopulation of naturally occurring and adaptive antibodies in humans. Recently, a variety of glycan-based microarrays emerged, allowing high-throughput profiling of a large repertoire of antibodies. As there are no direct approaches for comparison and evaluation of multi-glycan assays we compared three glycan-based immunoassays, namely printed glycan array (PGA), fluorescent microsphere-based suspension array (SA) and ELISA for their efficacy and selectivity in profiling anti-glycan antibodies in a cohort of 48 patients with and without ovarian cancer. The ABO blood group glycan antigens were selected as well recognized ligands for sensitivity and specificity assessments. As another ligand we selected P1, a member of the P blood group system recently identified by PGA as a potential ovarian cancer biomarker. All three glyco-immunoassays reflected the known ABO blood groups with high performance. In contrast, anti-P1 antibody binding profiles displayed much lower concordance. Whilst anti-P1 antibody levels between benign controls and ovarian cancer patients were significantly discriminated using PGA (p = 0.004), we got only similar results using SA (p = 0.03) but not for ELISA. Our findings demonstrate that whilst assays were largely positively correlated, each presents unique characteristic features and should be validated by an independent patient cohort rather than another array technique. The variety between methods presumably reflects the differences in glycan presentation and the antigen/antibody ratio, assay conditions and detection technique. This indicates that the glycan-antibody interaction of interest has to guide the assay selection.

High molecular weight neoglycoconjugates for solid phase assays

Adsorption of a carbohydrate on solid phase is the necessary stage of the immunosorbent assay (ELISA) and analogous methods of the study of carbohydrate-protein interaction. Usually physical adsorption on polystyrene requires a high concentration of conjugated carbohydrate and, thus, enormous consumption of it. In this study, we explored two approaches allowing more rational use of oligosaccharide (Glyc). The first of them is based on the covalent immobilization of neoglycoconjugates on the NH2-modified polystyrene; the second one is based on the elevated adherence of high m.w. neoglycoconjugates to polystyrene. Covalent immobilization of polyacrylamide conjugates, Glyc-PAA, provided a possibility to solve the problem, but the nonspecific binding of antibodies in ELISA proved to be unacceptably high. At the same time, the increase of the Glyc-PAA m.w. from 30 kDa to 2,000 kDa allowed a 10–20 fold decrease of its consumption, when using physical adsorption, whereas the assay background remained at the low level. The amount of 2,000 kDa Glyc-PAA that is sufficient for the coating of a standard 96-well plate corresponds to the nanomole level of oligosaccharide, this providing a possibility to use saccharides that are available in a very limited amount when studying the carbohydrate-protein interaction with solid-phase techniques. Published in 2005.

Neoglycoconjugates Based on Dendrimer Poly(aminoamides)

Neoglycoconjugates containing 4, 8, 32, and 64 terminal residues of B-disaccharide (BDI) or N-acetylneuraminic acid (Neu5Ac) attached to poly(aminoamide)-type dendrimers (PAMAMs) were synthesized. The ability of BDI conjugates to bind natural xenoantibodies (anti-BDI antibodies) and the ability of Neu5Ac conjugates to inhibit the hemagglutinin-mediated adhesion of influenza virus were studied. The biological activity of PAMAM conjugates turned out to be higher than that of free carbohydrate ligands, but less than that of multivalent glycoconjugates based on other types of synthetic polymeric carriers. A conformational analysis of PAMAM matrices and resulting conjugates was performed to determine the statistical distances between carbohydrate ligands. The computations revealed the tendency of the PAMAM chains toward compaction and formation of dense globules. The process results in a decrease in the distances between the carbohydrate ligands in the conjugates and, hence, could affect the ability of glycoconjugates to efficiently bind the polyvalent carbohydrate-recognizing proteins.

Biotinylated Multivalent Glycoconjugates for Surface Coating

Systematic studying of biological processes driven by multipoint high-cooperative carbohydrate recognition requires application of multivalent carbohydrates as tools. In this regard polyacrylamides with various pendant carbohydrate residues and labels are probably the most well advanced class of carbohydrate multimerics. Here we describe a synthetic approach to polyacrylamide-based glycoconjugates with biotin tag, with special emphasis to development of carbohydrate biosensors and arrays.

Specificity of neuraminidase activity from influenza viruses isolated in different hosts tested with novel substrates

Summary.Influenza A and B viruses isolated in Vero and Madin Darby canine kidney (MDCK) cells as well as in fertilised hen eggs were tested for the specificity of their neuraminidase (NA) activity. Novel glycoconjugates with variations of terminally bound sialic acid mimicking the three main receptor types for influenza viruses were synthesised. These new substrates together with the lectin from Ricinus communis were used in a solid phase microtitre assay for the detection of NA specificity. Egg or MDCK isolated virus strains tended to exhibit highest NA activity against 3′sialyl-bound sialic acid whereas Vero isolated strains favoured 6′sialyl-(N-acetyllactosamine)-bound sialic acid. Differences were more pronounced for influenza A than for influenza B strains.

Oligoglycines: Materials with unlimited potential for nanotechnologies

Peptides are the most promising molecules for nanotechnologies. Stable derivatives suitable for supramolecular design can be synthesized even from the simplest amino acid, glycine. Oligoglycines are able to form an unusual (noncanonical) structure, so-called polyglycine II, where peptide helices 31(ϕ = −76.9°, ψ = 145.3°) form a network of hydrogen bonds with six neighbors. The arrangement of linear oligoglycine in branched so-called di-, tri-, and tetraantennary peptides gives rise to a new class of molecules, which are distinguished by their simplicity, on the one hand, and by ample opportunities for self-assembly into complex supramolecular structures, on the other hand. This article summarizes the reports of synthesis of symmetrical antennary oligoglycines, studies of their self-assembly in plane atomic smooth layers and vesicles, and conditions of the assembly and disassembly of the polyglycine II structure in an aqueous medium. Structural features and peculiarities of assembly of the similar supramolecular structures on the surface of mica are described. The possible control of this process for preparing nanopatterns is demonstrated. Prospects are discussed for using this new class of materials in nanodesign. The concept of creating a new type of antiviral agents, supramolecular compounds whose formation from a precursor is promoted by the virus itself, is proposed.