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New amino acid derivatives with carbocycles of adamantine and quinaldic acid were synthesized and their in vitro antiviral activity against influenza A/H5N1 virus was evaluated. Experiments on cultured embryonic porcine kidney epithelial cells showed that amino acid derivatives suppressed viral replication. Tret-butyloxycarbonyl-DL-methionylsulfonyl-1-adamantayl ethylamine and benzyloxycarbonyl-L-trypthophanyl-1-adamantayl ethylamine compounds demonstrated high activity in all in vitro experiments. Moreover, some compounds showed virucidal activity against influenza A/H5N1 virus.

Fractions of aqueous and water-alcohol extracts of the birch fungus Inonotus obliquus have antiviral effect against the human immunodeficiency virus type 1 (HIV-1). Antiviral properties of low toxic extracts were manifested in the concentration of 5.0 μg/ml upon simultaneous application with the virus in the lymphoblastoid cells culture MT-4. The extract of the birch fungus can be used for development of new antiviral drugs, inhibitors of HIV-replication when used both in the form of individual drugs and as a part of complex therapy.

We studied the capacity amino acid derivatives of adamantane to inhibit replication of highly virulent avian influenza A/duck/Novosibirsk/56/05 (H5N1) virus in cultures of swine embryonic kidney cells. Amino acid derivatives of adamantane H-His-Rem and Ad(CH2-Ser-OMe)2 were characterized by lower toxicity than remantadine previously used in the treatment of influenza. Histidine-containing adamantane derivative (H-His-Rem) was the most effective and low-toxic inhibitor of influenza А/H5N1 virus replication and can be recommended for clinical trials to produce a preparation for the treatment and prevention of influenza.

The chaga mushroom (Inonotus obliquus) contains a wide range of excellent bioactive compounds. However, limited information exists on the antiviral activity of the compounds extracted from chaga. A number of subfractions of chaga were obtained using different solvents and different procedures. The subfractions of chaga extracted with water, alcohol, alkali were tested for their toxicity for the Vero cell culture and antiviral effect in the Vero cells infected with the Herpes simplex virus (HSV), Type 1. It was shown that most of the subfractions were not toxic for the Vero cells and had protective effect on the Vero cells infected with HSV. The subfraction IV in the concentration 5 microg/ml protected the Vero cells from cytodestructive action of HSV and no viral DNA was detected in infected cells treated with chaga extracts. Best protective effect was observed when compound was added before or within one hour after the Vero cells were infected with HSV.

For the first time in vivo, the model of the viral pneumonia in mice was used to study the antiviral activity against influenza A virus (H1N1) pdm09 synthetic derivatives of adamantane series including the amino acid residues and lipoid acid. It was found that the adamantane derivatives with histidine, serine, and lipoid acid could inhibit the rimantadine-resistant strain of the influenza A (H1N1) pdm09. As a result, the lifespan of the mice infected with the virus has increased by 1.6 times with respect to viral control. Thus, the possibility of restoration of antiviral properties of rimantadine both in vitro and in vivo by introducing into its molecular structure new functionally active groups was tested.

The antigen activity of the synthetic fluorescently labeled peptides, overlapping immunoresponsive epitops a.a. 7-19, 20-34 from N-end part and a.a. 73-85 from the central area of the nucleocapsid protein of C hepatitis virus, was tested using the method of fluorescent polarization immunoassay (FPIA) with 40 samples of the blood serum of patients with viral C hepatitis. A comparative study of analytic characteristics of FPIA method was performed, based on the application of synthesized peptides, as well as of the commercial ELISA test system (BEST anti-HCV-test 4, Vector Best Ltd.). The performed research revealed that the developed method has a high specificity and sensitivity level. The comparability of summary FPIA results with the commercial ELISA test system was 85%, which evidences the prospects of further research in this direction. The principal possibility of the application of the polarization fluorescent immunoassay for the determination of antibodies to the nucleocapsid protein of the C hepatitis virus in clinical serum samples was demonstrated.

New adamantane derivatives with amino acid residues and other bifunctional compounds were synthesized and their antiviral activity towards influenza A(H1N1)pdm and A(H3N2) viruses was studied. Some of these adamantane derivatives completely suppressed replication of remantadine-resistant influenza A virus strains.

Fractions of Inonotus obliquus fungus water extract exhibited a virucidal effect towards hepatitis C virus: it 100-fold reduced its infective properties within 10 min. The antiviral effects of fungus extracts manifested after preventive (24 h before infection) and therapeutic use (during infection of porcine embryo kidney cells). Moreover, the data indicate that the birch fungus extracts inhibit production of infective virus by porcine embryo kidney cells.

The amino acid and peptide derivatives of 1-adamantane carboxylic acid and rimantadine (18 compounds) have been first synthesized and investigated for their activity against influenza A virus (H1N1, H1N1v). In a series of obtained adamantine derivatives, some compounds have been found to be able to inhibit rimantadine-resistant influenza A virus strains. Thus, the antiviral properties of rimantadine can be restored.

Five phosphodipeptides were synthesized; two of them (H-Lys-Ala(P) and H-Pro-Ala(P) had interferon-induced activity. These dipeptides at millimolar concentrations (10(-4)) and 10(-5) M) induced the synthesis of late (40-hour) interferon in human peripheral blood lymphocytes. The dipeptides H-Lys-Ala(P) and H-Pro-Ala(P) showed a protective antiviral activity in in vivo studies when singly intraperitoneally administered to mice 2 hours before inoculation with murine encephalomyocarditis virus.

Three overlapping peptides containing linear B-cell epitopes and corresponding to the consensus sequence of hypervariable region 1 (HVR1) from protein E2 were studied for their capacity to interact with the sera from patients with acute and chronic hepatitis C. Antibodies to these peptides are detectable with the comparable frequency in both acute and chronic hepatitis C viral infection, other than after viral elimination. A relationship of the outcome of acute Infection to the presence or absence of antibodies to the test peptides has not been established. The level of antibodies against protein E2 HVR1 C-terminus is significantly higher in chronic hepatitis C.

A multi-enzyme immmune-assay test system was designed for serotyping of genotypes hepatitis C virus (HCV) and a method of such typing of the serum of patients with hepatitis C was worked out. The above test-system was worked out on the basis of a study of 10 type-specific peptides modeling different fragments from NS4-protein variable region of HCV. The designed test system was evaluated by using a set of 42 serum samples obtained at random from patients with chronic hepatitis C, which had been preliminarily genotyped by polymerase chain reaction. The serotyping makes it possible to identify the type-specific antibodies in the blood sera of patients, including those cases when viremia was absent. Differences in the circulation of HCV in Moscow (Russia) and Vitebsk (Byelorussia) were established by using the designed test-system.

A total of 136 patients with acute icteric hepatitis C, including patients with known outcome, were examined. Therefore, 46 serological samples, obtained from 13 patients with subsequent remission, and 63 samples, obtained from 13 patients, who subsequently developed the chronic disease stage, were analyzed. The serum of known outcome patients were examined, by using the immune-enzyme analysis method, to the antibodies of both class IgG, and IgM. Differences in the dynamics of the immune humoral response were established with due regard for a pathological course process, including the acute disease stage. The obtained results are interesting because of their prognostic values.

Solid-phase synthesis of three linear peptides overlapping the major immunodominant epitope of HDAg, which located within amino acid (aa) segment 53-108, and peptide aa 167-179 was carried out. The structure of the peptides corresponded to the sequences of isolates HDV type I. Their antigen reactivity was studied by indirect enzyme immunoassay with sera from patients with hepatitis D and from asymptomatic carriers of anti-delta antibodies. Two B-epitopes located within aa 53-80 and 71-93 appeared to be the most immnunoreactive. The use of these peptides in ELISA allowed anti-delta IGg antibodies to be detected with 95% confidence in serum of patients with hepatitis D and with 87% confidence in serum of asymptomatic carriers of anti-delta antibodies. Analysis of obtained data showed that these peptides can be used in new diagnostic anti-HDV tests.

Correlations between the spectra of antibodies to HCV proteins represented by various antigenic determinants and clinical variants of chronic HCV infection were studied. Synthetic peptides core-16, NS4-20, and NS5-23 simulating the immunodominant regions of the core, NS4 and NS5 proteins and recombinant proteins core-114 and NS4-86 were used as antigens. The results indicate that if the serum of an HCV patients contains no IgG to both antigenic determinants of NS4 or to NS5 in combination with any core antigenic determinant, a clinical and biochemical remission is highly probable. Chronic hepatitis C is characterized by the presence of IgG in high titers to both antigenic determinants of NS4 protein, particularly in combination with anti-NS5 IgG in low titers or none at all, or high titers of anti-core-16 IgG in combination with high titers of anti-NS4-20 IgG.

Aim: To examine diagnostic value of antibodies to various HCV antigens in patients with acute and chronic HCV-infection., Material and Methods: Enzyme immunoassay has tested blood sera from 136 patients with icteric acute hepatitis C (AHC) and 45 patients with chronic HCV infection for IgG antibodies to antigens of proteins core, NS4, NS5, HCV. Synthetic peptides core-16, NS4-20, NS5-23 were used as antigens., Results: Patients with icteric AHC had IgG antibodies to antigens of both structural protein core and non-structural proteins NS4, NS5 of HCV as early as the first 10 days of jaundice. Occurrence of anti-core and anti-NS4 increases with the disease duration. Incidence of anti-NS4 correlated with duration of previous intravenous drug addiction. In patients with AHC early in the icteric period anti-core, anti-NS4, anti-NS5 were present less frequently than in patients with chronic HCV infection having elevated levels of AlAT. Significant differences were found neither with the group with normal AlAt nor in the spectrum of the detected antibodies between patients with acute and chronic HCV infection., Conclusion: Despite different frequency of anti-core, anti-NS4, anti-NS5 detection in patients with icteric AHC and patients with chronic HCV-infection and high AlAT, their high incidence rate in this or that group and absence of differences by the spectrum of the studied antibodies do not allow the fact of their detection to be a diagnostic marker differentiating acute HCV-infection with chronic one.

Nine peptides from immunodominant (53-68 and 65-80 aa) and hypervariable (201-213 aa) regions derived from delta antigen sequences corresponding to 3 HDV genotypes were synthesized. Type specificity of antibodies to the resultant peptides was evaluated by indirect enzyme immunoassay with sera from patients with hepatitis D and asymptomatic carriers of anti-delta antibodies. Analysis of the results showed that HDV circulating in the Central Volga region belongs to type I in the majority of cases. High heterogeneity and changeability of HDV genome during the period of transition from acute forms to asymptomatic carriership was revealed. Possibility of circulation of new hybrid HDV strains causing mixed infection in Russia is discussed.

Solid-phase synthesis of 7 linear peptides overlapping the immunodominant N-terminal region of hepatitis C virus (HCV) core protein (aa 7-75) was carried out. Their antigen reactivity was studied by non-competitive ELISA with sera from patients with chronic HCV infection. Three B-epitopes located within aa 7-19, 20-34, and 39-75 appeared to be the most immunoreactive. Use of the set of synthetic peptides in ELISA detected anti-HCV core antibodies with 93% efficiency in comparison with ELISA and commercial anti-HCV Recomblot based on the use of commercial recombinant HCV core protein.

The reactivity of 100 sera taken from patients with different blood diseases and donors with respect to synthesized peptides in the variable area of protein NS4 of hepatitis C virus was studied. The presence of type-specific antibodies in the blood sera of patients with hepatitis C was shown. Two antigenic determinant corresponding to 1683-1705 and 1711-1732 amino acid residues in the protein area under study were detected. In hematological patients undergoing frequent blood transfusions mixed infection with different types of hepatitis C virus was registered; these types could be reliably determined with the use of synthetic peptides. The serotype determined with the use of peptides corresponded to the type of the circulating virus.

Three peptides corresponding to the 2295-2317 aa NS5 HCV region and individual parts of this region were synthesized. Antigenic properties of these peptides were investigated. The 2295-2317 aa region contains at least two epitopes of different nature. The full-sized peptide is more promising for the diagnostic studies. Optimal conditions for ELISA with this peptide were defined, allowing the maximum complete utilization of the potentialities of both epitopes.

Peptide fragments of hepatitis C virus (HCV) nonstructural protein NS4 capable of reacting with anti-HCV in enzyme immunoassay are synthesized. Addition of synthetic peptides to recombinant nucleocapsid HCV antigen absorbed on solid phase notably improves the efficacy of detection of antibodies to HCV in the sera of patients with hepatitis C.

A set of synthetic peptides of different length derived from proteins encoded by open reading frames (ORF) 1, 2, and 3 of hepatitis E virus (HEV) genome was synthesized and tested for antigenicity in indirect enzyme immunoassay. Peptides 414-433 (ORF2 protein) and 99-119 (ORF3) specifically react with antiHEV-positive sera collected during outbreaks in the Central Asian areas of the former USSR. The antigenic structure of the Central Asian variants and the Burmese types of HEV was found similar.

Interactions of collagenases I and II (clostridiopeptidases) from Clostridium histolyticum with hexapeptide substrates in which some L-proline residues are replaced by their D-analogues, as well as with the tripeptide chloromethyl ketone Z-Gly-Pro-Gly-CH2Cl were studied. A role of stereochemistry of the amino acid residues in the substrate was established and differences between the collagenases, with regard to their specific requirements to substrates, were revealed. The tripeptide chloromethyl ketone is shown to be a specific collagenase inhibitor modifying at the substrate-binding site in the active centre of these enzymes, most likely lysine residues.

Hexapeptide Lys-Gly-Pro-Asp-Ser-Gly analogous to the immunodominant fragment 141-146 of the epitope A of the influenza virus A(H3N2) hemagglutinin is synthesized. Conjugated with thyroglobulin and hemocyanine, the hexapeptide induced formation of highly specific antibodies with heterolytic properties in CBA mice. Antihexapeptide antibodies interact not only with the homologous antigen but also with hemagglutinin and influenza virus. Choice of the hexapeptide sequence is discussed.

A study was made of the specificity of the catalytic subunit of cAMP-dependent pig brain protein kinase with respect to structural analogs of the protein substrate, histone H1, namely: a) high-molecular-weight histone fragments obtained as the result of specific cleavage of histone with trypsin and N-bromsuccinimide; b) synthetic peptides-substrates; c) synthetic peptides-inhibitors. Analysis of the kinetic parameters estimated for these compounds allowed to evaluate the individual contribution of various elements of the primary and three-dimensional structure of histone in the processes of binding and phosphorylation. Factors of "near" and "remote" specificity in the protein substrate binding are suggested.

2-Methoxy-6-chloroacridine-9-yl- and 2-ethoxy-6-nitroacridine-9-yl-hydrazides of glycine, alpha- and beta-alanines, gamma-aminobutiric acid, epsilon-aminocaproic acid have been synthesized and their antimalarial activity has been investigated. The compounds were found to inhibit the growth of malaria parasite P. falciparum in in vitro cultures. Fifty per cent inhibitory concentrations ranged from 2 x 10(-7) to 6 x 10(-7) M and corresponded to therapeutic concentrations of known quinoline and acridine antimalarial drugs. The beta-alanine and gamma-aminobutiric acid derivatives were the most active and showed high activity against a chloroquine resistant strain of P. falciparum.

Four octapeptides containing the dipeptide fragments of the lac-repressor primary structure have been synthesized. The general scheme of synthesis consisted in the preparation of tetrapeptides using successive elongation from the C-terminus by the mixed anhydride method followed by their condensation into octapeptides.

The spectral criterion of a left-handed helix of the poly-L-proline II type was elaborated during the study of a number of synthesized oligopeptides (in a solid state and solution): (Gly-Pro-Pro)1-8, (Gly-Pro)1, (Gly-Pro-Ala)1-4, (Gly-Pro-Gly)1-4, (Gly-Pro-Pro) X (Gly-Pro-Gly)1-2(Gly-Pro-Pro), (Gly-Pro-Pro)n, (Orn3-Gly)n and also rat skin collagen by X-ray diffraction, circular dichroism and infrared spectroscopy methods; the characteristic shape of the left-handed helix CD spectrum was found. The change of spectral characteristics with the change of left-handed helix distortion was established. The linear noncooperative melting process of the left-handed conformation was demonstrated. The data obtained allow to determine qualitatively the presence of the left-handed helix in different polypeptides and proteins.