Viral infections occupy an essential place in modern medicine, particularly a large group of diseases caused by the influenza viruses. They are rapidly transmitted and mutate quickly, which can lead to significant socio-economic consequences. Silver nanoparticles (AgNPs) are considered to be an effective antimicrobial agent. This study shows that they have strong antiviral properties against the influenza A virus infection. Their absence of cytotoxicity at inhibitory concentrations demonstrates that they could be an effective antiviral agent against this virus. As AgNPs inhibit the influenza A virus replication and spread, they could also be successfully used as a post-infection virostatic agent.

Green synthesis of silver-containing nanocomposites based on polylactide (PLA) was carried out in two ways. With the use of green tea extract, Ag⁺ ions were reduced to silver nanoparticles with their subsequent introduction into the PLA (mechanical method) and Ag⁺ ions were reduced in the polymer matrix of PLA-AgPalmitate (PLA-AgPalm) (in situ method). Structure, morphology and thermophysical properties of nanocomposites PLA-Ag were studied by FTIR spectroscopy, wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods. The antimicrobial, antiviral, and cytotoxic properties were studied as well. It was found that the mechanical method provides the average size of silver nanoparticles in the PLA of about 16 nm, while in the formation of samples by the in situ method their average size was 3.7 nm. The strong influence of smaller silver nanoparticles (3.7 nm) on the properties of nanocomposites was revealed, as with increasing nanosilver concentration the heat resistance and glass transition temperature of the samples decreases, while the influence of larger particles (16 nm) on these parameters was not detected. It was shown that silver-containing nanocomposites formed in situ demonstrate antimicrobial activity against gram-positive bacterium S. aureus, gram-negative bacteria E. coli, P. aeruginosa, and the fungal pathogen of C. albicans, and the activity of the samples increases with increasing nanoparticle concentration. Silver-containing nanocomposites formed by the mechanical method have not shown antimicrobial activity. The relative antiviral activity of nanocomposites obtained by two methods against influenza A virus, and adenovirus serotype 2 was also revealed. The obtained nanocomposites were not-cytotoxic, and they did not inhibit the viability of MDCK or Hep-2 cell cultures.

Atmospheric pressure metal–organic chemical vapour deposition was used to synthesize Ag-containing ZnO nanostructures of different morphology on Si substrates coated by Ag. Ag from Ag/Si substrates and Ag from silver acetylacetonate after its decomposition were used as a catalyst for ZnO nanocrystal growth for deposition of ZnO nanostructures with different morphologies. We investigated the relation of the structural parameters and chemical composition probed by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy with the photoluminescence (PL) properties and electron–phonon coupling (EPC) reflected in the multi-phonon Raman spectra. The Raman and PL spectra were studied at different powers of the exciting laser radiation (P _exc). The spectral position and width of the phonon Raman peaks and the near bandgap PL band at low P _exc are supposed to be determined by the structural quality of the surfaces/boundaries of the crystallites. The intensity of the near-bandgap and defect-related PL and the magnitude of the EPC are additionally affected by the dopant concentration. Because of the large crystallite size (>30 nm, determined from XRD), the effects of phonon or electron confinement are negligible in these nanostructures. The behaviour of the position and width of phonon and PL bands with increasing P _exc indicates that the heat dissipation in the film, which is dependent on the nanostructure morphology and Ag content, plays an important role. In addition, the cytotoxicity of ZnO:Ag nanostructures was investigated by using monolayer cell cultures of epithelioid origin Madin-Darby bovine kidney and Madin-Darby canine kidney cells at a MTT assay revealing that the level of silver doping of ZnO nanostructures, their morphology, and geometric dimensions determine their toxic effects.

Introduction: In the current scenario of antiviral research, lactic acid bacteria (LAB) and their derived polymers or polysaccharides are considered potential candidates in antiviral therapy to prevent or treat viral infections in both human and animals with remarkable efficacy and might have significant contribution in medicine and pharmaceutical industries in future. The aim of this work was to study the anti-herpetic activity of exopolysaccharides produced by Leuconostoc sp. Methodology: The strains of the LAB were isolated from fermented homemade vegetables: apples, tomato juice, and sauerkraut. Exopolysaccharides (EPSs) were isolated from the culture fluid. Cytotoxicity and antiherpetic activity of 7 EPSs (15a, 48a, 33a, 43a, 2t, 19s, and 6s) were studied using MTT assay. The influence of EPSs on the herpes simplex virus 1 type (HSV-1) was determined by the virucidal, adsorption and penetration assays. The impact of the EPSs on the cell cycle under a condition of HSV-1 infection was analyzed using flow cytometric analysis of propidium iodide-stained cells. Results: All EPSs demonstrated the minimal cytotoxicity of cells and their CC₅₀ values were >3.5 mg/ml. It was determined, that only EPSs 2t, 19s, and 6s significantly inhibited HSV-1 reproduction; their EC₅₀ value equal to 0.2 and 0.5 mg/ml, and the selectivity index was in the range of 39 – 52. Moreover, their showed virucidal activity when were added to virus 3 h before adsorption reduced HSV-1 infectivity by 86 – 97%. Our studies revealed that these EPSs were able to prevent the HSV-1 attachment to cells and penetration into cells in a different manner, reducing HSV-1 production by 70 – 99 %. Furthermore, the normalization of the number of cells in all phases of the cell cycle compared with the profile of infected cells and the increasing number of cells in G1 phase to 79% compared with the control values of viral infections were determined after using of EPSs. Conclusion: This study presents the first data indicating an enormous potential of using EPSs the genus Leuconostoc sp. for lower or hinder the spread of diseases caused by herpesviruses. Funding: Publications are based on the research provided by the grant support of the State Fund for Fundamental Research (project F83).

Mixed viral infection is one of the current and unexplored issues of human infectious diseases. A special place in the development of these pathologies is occupied by adeno- and herpes viruses that are able to persist for a long time in a latent condition in the body. There is a huge lack of knowledge about antiviral activities of specific drugs during the mixed infections. The study of know drugs and discovery of new compounds using not only standard mono-infections but also with created mixed infections is a topical and a new direction in antivirus screening. Previously in our department, the models of adeno-herpetic infections in cells of different origins were created and the features of the development of viral infections in these systems were studied. The model of simultaneous adeno-herpetic infection of MDBK cells was used for the analysis of the antiherpetic drug acyclovir (ACV) and for research of new fluorine-containing derivatives of L-phenylalanine (10S-23 and 10S-24, synthesized in Institute of Organic Chemistry of the NAS of Ukraine). Determination of the antiviral activity accessed via real-time PCR and infectious virus yield reduction assay demonstrated the inhibitory effect of these compounds on the late stage of the HSV-1 and HAdV5 reproduction. With the presence of 10S-24 and ACV in the conditions of mono-infection, HSV-1 DNA replication was inhibited on 39 and 100%, respectively. Furthermore, the significant delays of HSV-1 reproductions were observed, the titer of virus obtained de novo reduces on >99%. It was shown that for adenovirus infection of the cells, all compounds reduced the titer of the virus on 34-96%. Use of the ACV under mixed infection led to the 46% loss of the drug activity against HSV-1. The application of 10S-23 and 10S-24 at mixed infection induced a decrease of effectiveness of the compounds relatively herpes simplex virus by 58-73% and 16-57%, respectively. It was shown that compounds have been not effective against HAdV5 under conditions of co-infection of cells. An abnormal action of drugs in co-infected cells indicates the need for further study of the mechanisms and targets of antiviral activity of compounds in such conditions, because using these compounds can be ineffective in medical practice. Acknowledgements This work was supported by a President’s of Ukraine grant for competitive projects F70 of the State Fund for Fundamental Research.

Першим вірусом класифікованим, як онкологічний був вірус Епштейна-Барр. Метою роботи було дослідити біологічні властивості фторованих похідних на основі урацилу. Згідно прогнозування PASS, сполуки G26 та G27 можуть мати противірусну активність. Анти-ВЕБ активність in vitro була показана для обох досліджуваних сполук. Таким чином, похідні урацилу є перспективними для створення нових антивірусних агентів