Effect of 6-azacytidine on the course of experimental adenoviral infection in newborn Syrian hamsters.

Adenoviral infection is a serious human pathology leading to respiratory, gastrointestinal and ocular disorders and epidemic outbreaks, especially in children's groups. Here we present the results from an investigation of anti- adenoviral effect of 6-azacytidine (6-AC) both in vitro and in vivo. The selectivity index of 6-AC for adenovirus type 5 in HEp-2 cells was 374, the 50% effective concentration was 0.5 mg/ml. For in vivo investigations we developed a model of disseminated adenoviral infection in newborn Syrian hamsters. The infectious virus was recovered from the liver, kidney, lungs and heart. Application of 6-AC led to a reduced period of the virus presence (7 days in the liver and 4 days in the kidney and heart) and lowered virus titers on day 3 post-inoculation (p.i.) (liver - 2.7 and 4.1, heart - 0 and 3.2, kidney - 0 and 2.4 log(10 )CPD(50)/mg tissue weight, in the presence and absence of 6-AC, respectively). Application of 6-AC to newborn Syrian hamsters led to partial destruction of their splenocytes. The results obtained suggest that 6-AC or 6-ACbased drugs with lower toxicity or applied topically may be suitable for therapy and prevention of adenoviral infection in humans.

[Evaluation of metabolic parameters in vitro as a model for testing the cytotoxicity of antiviral drugs].

A new test system based on in vitro assessment of the cellular viability and/or metabolism is proposed, which offers an informative approach to the screening of antiviral drugs. Cytotoxic effects of the antiviral drugs rimantadine and polyrem were studied on the cultures of some mammalian cells. The results of short-term (2 h) exposures with the drugs tested were close to their LD50 values in mammals, which makes the proposed test system promising for the assessment of drug toxicity in vivo for the whole organism. A study of the state of cell metabolism after a long-term (48 h) exposure showed that the system of endocytosis is more sensitive than other indices with respect to antiviral drugs. Is was demonstrated on the cell level that the binding of drugs into polymeric complexes can decrease the degree of its cytotoxicity: the toxicity of polyrem (a polymeric complex of rimantadine) was lower as compared to that of the equimolar concentration of rimantadine or a mixture of rimantadine with a polymeric carrier.

[Protective effect of cycloferon in experimental influenza]. / Zashchitnoe de'istvietsikloferona pri éksperimental'no'i grippozno'i infektsii.

Protective effect of granulated cycloferon has been studied in albino mice infected with influenza. The drug induced interferon production and prolonged the life span, decreased the mortality, suppressed the virus reproduction in the lungs, and decreased the infective activity of the virus. Morphologically the drug decreased the intensity of viral lesions in the bronchiolar epithelium, impeded the infection dissemination, and stimulated the productive (cellular) component of local inflammatory reaction. No influence on the development of chronic lesions in the lungs was detected.

[Intracellular localization of cycloferon, its binding with DNA and stimulation of cytokines expression after exposure to cycloferon]. / Issledovanie vnutrikletochnoi lokalizatsii tsikloferona, sviazyvaniia ego s DNK i stimuliatsii ékspressii tsitokinov v kletkakh pri vozdeistvii tsikloferona.

Despite the wide usage of immunomodulating preparates including interferon inducers in medical practice little is known about their mechanism of action. We investigated some theoretical aspects of action of potent interferon inducer--cycloferon (10-carboxymethyl-9-acridanone), such as intracellular localization, ability to DNA binding and cytokine expression stimulation. This preparate has been found to be localized in nuclei of monocytic cells U-937, T- and B-lymphocytes and HeLa cells. In Hep-2 line cycloferon was bound to cells from non-adhesive subpopulation and was not detected in cells of monolayer. Human fibroblasts did not bind the substance. Interaction with double-stranded but not with single-stranded DNA occurred at pH lower than 4.7 regardless of the GC-contain. As shown by dot-hybridization cycloferon stimulated the transcription of interferon-alpha gene in U-937 cells 29-44-fold compared to the control but did not affect the transcription of tumor necrosis factor and interleukin-2 genes. Our data allow to propose that some specific receptor exists in cell with affinity to cycloferon.

[The use of cycloferon in the therapy of experimental herpetic keratitis]. / Ispol'zovanie tsikloferona v terapii éksperimental'nogo gerpeticheskogo keratita.

The cycloferon efficacy was investigated in the treatment of experimental herpesvirus kerato-conjunctivitis in rabbits. The model was demonstrated to reflect the main aspects of herpesvirus eye lesions in humans. Cycloferon application similarly to that of known interferon inducer poludan has been shown to enhance processes of inflammation and subsequent regeneration of eye tissues as well as to decrease mortality of animals due to the generalization of infection.

[Effect of liposomal beta-carotene on experimentally lethal influenza infection]. / Vliianie liposomal'nogo beta-karotina na éksperimental'nuiu letal'nuiu grippoznuiu infektsiiu.

Effect of beta-carotene on experimental infection with A/Aichi/2/68 (H3B2) is studied in mice infected in an infective dose of 5-10 LD50. The drug notably decreased the mortality in experimental group in comparison with the control. Disease symptoms were less expressed and deaths observed later (7 days vs. 4 in the control) in mice treated with beta-carotene. Histological analysis of the lungs showed smaller foci of lesions. Metaplastic changes in the bronchial epithelium, typical of late terms of infection, were far less expressed in these animals. On the other hand, virus titers decreased negligibly in comparison with the control group. Electron-microscopic study of the effect of beta-carotene on virus population showed that virus replication in chick embryos in the presence of beta-carotene led to an increase in the percentage of filamentous and giant polygenome virus particles. The data indicate that beta-carotene is a promising drug for prevention and treatment of influenza.

[Pathogenesis of severe influenza]. / Patogenez tiazhelykh form grippa.

The paper analyzes the contribution of active oxygen radicals whose formation was observed in the inflammatory foci, as well as in generalized influenza infection. There is a correlation between the inactivation of protease inhibitors (alpha-1-antitrypsin) and the increase in the efficacy of virus protein proteolysis, in particular hemagglutinin and hence the acceleration of the infection activation of viral particles. The proteolytic provision of infection viral particle activation occurs due to cell membrane lipid peroxidation, by impairing their barrier function, this is an important condition for the generalization of infection and development of endemic processes. With this, involvement of St. aureus that secretes serine proteases accelerates the closing of the vicious circle of pathogenetic processes and further generalization of infection. The scheme of pathogenesis is based on the data on the molecular mechanisms of formation of free oxygen radicals, as well as on the structure of cell inhibitors of virus proteins.

[The antiviral activity of deitiforin in experimental para-influenza infection]. / Protivovirusnaia aktivnost' deitiforina pri éksperimental'noi paragrippoznoi infektsii.

Deitiforin in HEp-2 cell culture was shown to inhibit replication of the reference PIV-3 strain when administered 1 hour before virus inoculation. The most marked effect of the drug was observed in the first 4 days of observation. In experimental newborn mice infected with parainfluenza virus 3 deitiforin protected the animals from developing the infection. In humans given deitiforin reaction to vaccination was found to develop 5-6 times more rarely than in the control group, PIV-3 could be isolated twice as rarely, and a diagnostically significant rise of specific antibody levels was observed less frequently.

Studies of natural population variability of parainfluenza viruses during their epidemic circulation.

The population of circulating serotype 3 parainfluenza virus strains isolated in different years proved to be sufficiently polymorphic concerning its antigenic and biological features as well as their virulence for newborn hamsters. The highly virulent strain population appeared to have an antigenic pattern different from that of the prototype strain. The epidemic caused by it in groups of school and preschool children was more intensive as compared to that induced by avirulent strains population.

[Isolation and comparative study of highly reproductive recombinant influenza A viruses with a high antibody sensitivity]. / Poluchenie i sravnitel'noe izuchenie vysokoreproduktivnykh rekombinantov virusa grippa A s vysokoi chuvstvitel'nost'iu k antitelam.

The possibility of generating avid and highly reproductive recombinants of influenza A virus (H3N2, H3N1) using strain A/PR/8/34 (H1N1) as a donor of high reproductive activity was demonstrated. In the process of recombination, the transmission of the gene responsible for synthesis of avid hemagglutinin H3 from one virus variant to another provides for high avidity of recombinants. However, a possible influence of other influenza A virus genes on the manifestation of avidity cannot be ruled out.

[Structural characteristics of a population of antigenic variants of the influenza A(H3N2) virus]. / Osobennosti struktury populiatsii antigennykh variantov virusa grippa A(H3N2).

The data have been obtained indicating that clone distribution by the antigen avidity in the population of influenza A (H3N2) virus corresponds to normal distribution. The degree of avidity of individual strains is determined by the predominant content of clones with high or low avidity. Virus purification by ultracentrifugation in sucrose density gradient results in increasing the avidity of the preparation as compared with the original allantoic cultures. Defective virions may differ in avidity from intact viral particles of the same strain and in this way affect the "total" avidity of a virus preparation.

[Detection of rotavirus in the feces of children with diarrhea]. / Obnaruzhenie rotavirusa v fekaliiakh detei, bol'nykh diarei.

Bacteriological and virological examinations of feces from sick children diagnosed as having an "enteric infection of obscure etiology" were carried out. Out of 30 fecal specimens 6 showed positive results in agar gel diffusion test with antiserum to calf diarrhea rotavirus confirmed by electron microscopy. The relationship of virological and bacteriological findings and age of the patients was established. Differences in the clinical manifestations of the disease in virus-positive and virus-negative patients were observed.