[Pathogenicity of noncytophatic isolates of bovine viral diarrhea virus in experimentally infected seronegative calves].

The results of experimental infection of seronegative calves with three non-cytopathogenic (NCP) isolates of BVDV isolated from cattle with different clinical manifestations of the disease belonging to genotype 1 (subgenotype 1a, 1b and 1d) are presented. All tested isolates showed the virulence for seronegative calves 4 to 6 months of age. Belonging to biotype did not correlate with the ability of the virus to infect the lymphoid tissues and to induce leukopenia. All isolates of the virus led to "transiting" leukopenia (up to 2880-3800 kl/mm3) for 8-10 days after infection. Isolate cluster 1d was more virulent and caused the development of a mild respiratory syndrome and short-term diarrhea. The virulence was "strain-dependent".

[A comparative study of the antiviral activity of chemical compounds concerning the orthopoxviruses experiments in vivo].

In the experiments using intranasal (i/n) infection of mice with the ectromelia virus (EV) in a dose 10 LD50/head (10 x 50% lethal doselhead) or with the monkaypox virus (MPXV) in a dose 10 ID50/head (10 x 50% infective dose/ head) it was demonstrated that the antiviral efficiency of chemical compounds - the condensed derivatives of pyrrolidin-2,5-dion, as well as their predecessors and the nearest analogues, synthesized in Novosibirsk Institute of Organic Chemistry of the Siberian Branch of the Russian Academy of Sciences (NIOCH SB RAS) was observed. As a positive control we used the antipoxvirus chemical preparation ST-246 available from SIGA Technologies Inc. (USA), synthesized in NIOCH SB RAS by the technique suggested by the authors. It was demonstrated that the compound NIOCH-14 (7-[N'-(4-Trifluoromethylbenzoil)-hydrazidecarbonil]-tricyclo[3.2.2.02,4]non-8-en-6-carbonic acid) possessed comparable with ST-246 antiviral activity concerning EV and MPXV on all indicators used. Therefore, at infection of mice with EV (strain K-1) and peroral administration of NIOCH-14 and ST-246 in a dose 50 mkg/g of mouse weight (12-14 g) within 10 days the survival rate and average life expectancy of mice authentically exceeded the control levels. EV titers in lungs through 6 days after infection in the same groups were lower than in the control. In addition to that, after 7 days of infection of mice with MPXV (strain V79-1-005) and daily peroral administration of NIOCH-14 and ST-246 in a dose 60 mkg/g of mouse weight (9-11 g) authentic decrease in a part of infected animals and MPXV titers in lungs was observed.

[Validation of the modified algorithm for predicting host susceptibility to viruses taking into account susceptibility parameters of primary target cell cultures and natural immunity factors].

The paper presents results of testing a modified algorithm for predicting virus ID50 values in a host of interest by extrapolation from a model host taking into account immune neutralizing factors and thermal inactivation of the virus. The method was tested for A/Aichi/2/68 influenza virus in SPF Wistar rats, SPF CD-1 mice and conventional ICR mice. Each species was used as a host of interest while the other two served as model hosts. Primary lung and trachea cells and secretory factors of the rats' airway epithelium were used to measure parameters needed for the purpose of prediction. Predicted ID50 values were not significantly different (p = 0.05) from those experimentally measured in vivo. The study was supported by ISTC/DARPA Agreement 450p.

[Quantitative assessment of in vitro neutralizing activity of secretory factors from rat lungs against influenza virus].

Secretory factors were isolated by lung wash followed by centrifugation to remove cells, dialysis of supernatant to remove NaCl salt, lyophilization of the lavage fluid and resuspention of the lyophilization product in an isotonic NaCl solution. It was shown that biological activity of influenza virus /Aichi/2/68 (3N2) significantly decreased (p = 0,01) from 8,17 +/- 0,10 to 7,14 +/- 0,20 IgEID50/ml during its incubation with secretory factors at 37 degrees C for 1 hr and to 7,92 +/- 0,17 IgEID50/ml in isotonic NaCl solution in the absence of these factors. Their concentration in the incubation medium was estimated to be 9.1 +/- 0.7% of their level in the lungs.

[A study of possibility to predict the sensitivity of different respiratory tract divisions to influenza].

To predict a potential value of a viral ID50 for a macro-organism of interest (e.g. humans), it is necessary to determine in vitro two parameters of the interaction of the virus with susceptible cells of the host, i.e. the probability of the virus' productive absorption on a susceptible cell and the average virus yield per cell. A different macroorganism (a model animal) and primary cells obtained from it can be used to determine the value of a scale factor, which accounts for the difference between the values of the probability of the virus' absorption measured in vivo and in vitro. An original mathematical model is used to convert the above-mentioned data to ID50 for the macroorganism of interest. It was shown that the method of cultivating influenza virus (A/ Aichi/2/68) in primary suspension culture of respiratory tract cells of rats and two breeds of mice may be used to estimate potential human susceptibility to novel influenza viruses. This work was sponsored by DAPRA, USA, and performed under the contract 450p to the International Science and Technology Center, Moscow.

[Target-cell susceptibility and lung phagocyte activity in mice with influenza virus resistance lowered by glucocorticoidal immunosuppression].

The results of the study showed that subcutaneous kenalog (Kn) lowered the resistance of mice to influenza virus (InV), as was seen by a decrease in 50% lethal dose and an increase in the degree of pulmonary tissue lesion, and the susceptibility of the lungs to InV, seen by the fact that 50% aerogenic infective dose (AID50) was significantly higher in the main group (Kn+InV) than in controls, which received Hanks solution subcutaneously (HS+InV). In vitro, 50% infective doses of InV for suspension of pulmonary and tracheal cells, characterizing their susceptibility to InV, were similar in Kn mice and controls. At the same time, lower resistance and higher degree of pulmonary inflammation noted in Kn mice after receiving a dose of InV that was much higher than an infecting one, was accompanied by the prevalence in the number as well as phagocyte and superoxide-producing activity of neutrophiles (Nph) over the same parameters for alveolar macrophages (AMph) as early as two days after receiving InV dose, vs. InV-infected controls. Evidently, one of the reasons for lower resistance to InV after Kn administration is significant disbalance between the functional activity of AMph and Nph populations. Ineffective AMph clearance of the lungs from InV and excessive number of recruited Nph and products of tissue disintegration may favor the development of respiratory failure and infectious-toxic shock, which leads to lower resistance in animals which receive Kn before InV infection.

[Reactogenicity, safety and immunogenicity of a recombinant bivaccine against smallpox and hepatitis B in limited clinical trials]. / Reaktogennost', bezopasnost' i immunogennost' rekombinantnoi bivaktsiny protiv ospy i gepatita B v ogranichennykh klinicheskikh ispytaniiakh.

The reactogenicity of the embryonic live recombinant variola and hepatitis B bivaccine as tablets (Revax-BT) as well as its safety and immunogenicity were evaluated in clinical trials made in volunteers who had previously immunized or not with variola vaccine. A preliminary conclusion was made on a lack of side effects and drug safety in primary vaccination and been revaccination with low and high doses. Primary immunization of volunteers and as bivaccination with high doses stimulated the most pronounced immune response to the vaccine virus versus such effect observed in immunization of volunteers with low vaccine doses. Humoral immune response to HBs was observed in 75% of volunteers of both groups after as bivaccination. Such response was most pronounced in examinees immunized with low vaccine doses versus those who received high bivaccine doses. At the same time, no protective levels of humoral immunity response to HBs Ag were observed in volunteers first vaccinated.

[A new setup for the generation and studies of mono-disperse microbiological aerosols in medical-and-biological research]. / Novyi kompleks dlia polucheniia i izucheniia monodispersnykh mikrobiologicheskikh aérozolei v mediko-biologicheskikh issledovaniiakh.

A setup for the generation and studies of mono-disperse microbiological aerosols is described in the paper. Coefficients of 3 microm aerosol deposition in the respiratory tract of mice and rats were refined by using the above setup. The probability of deposition of such particles in the trachea and lungs of mice was proven to be equal to 1.2 +/- 0.1% and 2.6 +/- 0.2%, respectively. The probability for rats was equal to 3.2 +/- 0.2 and 11.8 +/- 0.9%, respectively. The distribution of deposited aerosol particles was determined by electron microscopy.

[Pulmonary cell susceptibility in mice and rats to influenza virus when infected in vivo and in vitro]. / Vospriimchivost' kletok legkikh u myshei i krys k virusu grippa pri infitsirovanii in vivo i in vitro.

The purpose of the case study was to evaluate comparatively the relative contribution of cell susceptibility and the inhibiting effect of factors of pulmonary epithelial lining in mice and rats to influenza virus A/Aichi/2/68 (H3N2) adapted to mice as related with the development of infection process in the lungs of experimental animals when infected in vivo and in vitro. Mice and rats were infected aerogenically with different doses of influenza virus. The primary cell-culture suspensions sampled from the lungs of mice and rats were used to study the adsorption and dynamics of influenza virus production in infection by different dose of influenza virus in vitro. The cell suspensions were shown to be able to produce the influenza virus for as long as 48 hours after infection. It was for the first time that the results denoted the identical susceptibility of primary pulmonary cells in mice and rats to influenza virus. A lower pulmonary susceptibility to influenza virus in rats versus mice could be indicative of that the surface factors of epithelial lining contribute essentially to shaping the pulmonary susceptibility to influenza virus since there is no difference of the susceptibility of pulmonary cells to influenza virus between the two above animals' species.

[Antiviral activity of oral ultralow doses of antibodies to gamma-interferon: experimental study of influenza infection in mice]. / Protivovirusnaia aktivnost' sverkhmalykh doz antitel k gamma-interferonu pri peroral'nom vvedenii: éksperimental'noe issledovanie grippoznoi infektsii u myshei.

Course intragastric administration of ultralow doses of human gamma-interferon antibodies (ULD anti-IFN-gamma) to intact mice resulted in an increase of endogenous IFN-gamma production by the animal lymphocytes. Oral prophylactic administration of ULD anti-IFN-gamma significantly lowered the influenza virus concentration in the animal lungs at the initial stage of the aerogenous infection: in 2 (p = 0.05) and 3 (p = 0.07) days after the contamination. The therapeutic antiviral effect of ULD anti-IFN-gamma in mice with influenza was evident from a significant decrease of the influenza virus concentration in the lungs of the animals on the 4th (p = 0.05) and 5th (p = 0.07) days after the contamination. The antiviral effect of ULD anti-IFN-gamma after the prophylactic and therapeutic use is likely provided by induction of endogenous IFN-gamma.

[Possibilities of culturing mutant variants of Ade12 adenoviruses in 293 cell culture]. / Vozmozhnost' kul'tivirovaniia mutantogo varianta Ade12 adenovirusa na kul'ture kletok 293.

The results of polymerase chain reaction and of DNA sequencing of the Adel2 mutant variant of adenovirus serotype 5, passaged 10 times and capable of selectively infecting and lysing the p53-deficient human tumor cells, are indicative of a high stability of its genotype and of the phenotypic properties acquired by it in successive passage on 293 cells. The absence of admixtures of wild-type adenovirus was clearly shown in the cultivation and passage processes. It was revealed in an experimental analysis of virus-productive properties of the studied continuous cell culture 293 by using the method of multilayer cultivation, that the maximal Adel2 yield is obtained at the 50% cytopathic effect. Virus doses, that are effective for cell-culture contamination, are within a range of 100-10 TCPE50 per cell. In order to spare the viral material, the infecting dose of 10 TCPE50 per cell was chosen to infect a cell monolayer.

[Mechanisms of mice resistance to influenza virus A/AICHI/2/68 after preventive injection with polyprenols ]. / Mekhanizmy rezistentnosti myshei k virusu grippa A/AIChI/2/68 pri profilakticheskom vvedenii poliprenolov.

Preventive effect in influenza can be attained by intramuscular injections of fir (Abies) polyprenols. One of 5 tested polyprenol preparations (No. 1), injected 2 days before aerogenic infection with influenza virus, reliably protected mice from disease. Mice pretreated with polyprenol preparations or Hanks' solution did not differ by accumulation of interferon in the lungs One day after aerogenic infection. Three days after injection of polyprenol preparation No. 1 the weights of the spleen and thymus significantly decreased. One day after injection cell count in the bronchoalveolar tract of mice was almost 2-fold higher than in the control at the expense of lymphocytes and macrophages. After 3 days the relative and absolute counts of macrophages decreased and those of lymphocytes decreased significantly. Three days after injection macrophages were 2-fold more active in absorption of zymosan granules. Preparation No. 1 affected the production of superoxide anion radicals, whose production by all macrophages in the bronchoalveolar tract of mice was significantly higher on day 1 postinjection than on day 3 and higher than on days 1 and 3 after injection of preparation No. 2.

[Prophylactic efficacy of aerosol preparations based on Abies siberica polyprenols in experimental influenza infection]. / Profilakticheskaia éffektivnost' aérozolei preparatov na osnove poliprenolov pikhty sibirskoi pri éksperimental'noi grippoznoi infektsii.

Preliminary investigations showed high preventive activity of two of three aerosol preparations of Abies sibirica polyprenols with nonionic surface active substances towards influenza infection. At least 2 aerosol administrations are needed to attain a high protective effect, the second dose depending on the first. Relationship between animal reaction to influenza virus infection changed in a nonmonotonous mode, depending on the drug dose injected during the first treatment: as the dose increased, the death rate first decreased and reached the minimum and then increased again. Such a reaction to aerosol treatment can be explained by the hypothesis of hyperstimulation followed by exhaustion of the host defense systems after high doses of the preparation.

[Mechanisms of action of aerosol preparations based on Abies siberica polyprenols in experimental influenza infection]. / Mekhanizmy deistviia aérozolei preparatov na osnove poliprenolov pikhty sibirskoi pri éksperimental'noi grippoznoi infektsii.

Humoral and cellular mechanisms of Abies sibirica polyprenol effects on nonspecific resistance of mice to influenza A/Aichi/2/68 virus were investigated. Two aerosol doses of polyprenols had a high protective effect in mice challenged with influenza virus. Aerosol polyprenol preparations in the studied doses induced no interferon or tumor necrosis factor production in the lungs. Lung macrophage counts and capacity to produce superoxide anion radicals increased in survivors after influenza in comparison with intact animals. Double aerosol administration of polyprenols prior to influenza infection promoted an increase in the thymus weight, bronchoalveolar tract cell counts (predominantly at the expense of lymphocytes), and of superoxide-producing potential of macrophages, which, in turn, can contribute to improvement of the defense potential of the organism towards influenza virus.

[Sensitivity of white mice to influenza virus (A/Aichi/2/68) in aerogenic infection]. / Chuvstvitel;nost' belykh myshei k virusu grippa (A/Aichi/2/68) pri aérogennom zarazhenii.

Polydispersed aerosols from allantoic fluid of chick embryos induced with influenza virus with different median weight aerodynamic diameters of corpuscles (0.5, 0.8, 1.1, 2.2, and 6.0 mu are effectively deposited in respiratory organs of mice weighing 18-19 g. The sensitivity of mice of different weight to aerogenic infection with influenza virus (strain A/Aichi/2/68) was virtually the same. The efficacies of aerogenic 50% infective and lethal doses (1.8-2.5 lg) for mice of the same weight were different. The sensitivity of mice to aerogenic infection and of developing chicken embryos to the virus (ID50 = EID50) is the same. Mice weighing 10-19 g can be infected via airways with adapted influenza virus in studies of therapeutic and prophylactic effects of drugs.

[Some aspects of interferon formation in white mice]. / Nekotorye aspekty interferonoobrazovaniia v organizme belykh myshei.

White mice weighing 14-16 g were intranasally infected with LD50 of influenza virus (A/Aichi/2/68 strain). High levels both of virus and interferon were detected in the lung. Sufficient virus accumulation in the nasal cavity occurred with low interferon induction. At the same time high blood interferon levels corresponded to sporadic low viremia. Intraperitoneal injection of the interferon inducer ridostin (a pharmacological formulation of dsRNA) to BALB/c mice (18-20 g) in a dose of 5 mg/kg induced intensive blood accumulation of interferon with its peak at 8 hours postadministration (2560 U/0.2 ml), but interferon was not detected in the respiratory tract and brain of these mice. Intranasal (15 mg/kg) and aerogenic (0.4-0.6 mg/kg) administration of ridostin induced interferon mainly in the upper respiratory tract and lung. The regularities found are in agreement with the data on interferon induction by other dsRNA preparations, which makes it necessary to design dosage forms of interferon inducers for respiratory application in influenza.

[Methods for controlling colonization of air and laboratory surfaces by pathogens of certain especially dangerous viral infections]. / Metody kontrolia obsemenennosti vozdukha i poverkhnostei pomeshchenii vozbuditeliami nekotorykh osobo opasnykh virusnykh infektsii.

Regular check-ups of the laboratory environment (air and working surfaces) for contamination with the objects of investigations are obligatory for laboratories working with viruses causing grave diseases, such as Ebola, Marburg, and Machupo fevers and Venezuelan equine encephalomyelitis. Methods for indication and identification of these agents have been developed and experimentally tried.

[Some pathogenetic characteristics of influenza infection in white mice]. / Nekotorye patogeneticheskie kharakteristiki grippoznoi infektsii u belykh myshei.

Influenza virus strain A/Aichi/2/68 replicated only in the lungs, nasal cavity, and trachea after intranasal challenge of white mice weighing 14-16 g. Rapid accumulation of the virus was associated with a somewhat delayed accumulation of endogenous interferon in the lungs, the concentration of interferon gradually decreasing by the end of the disease. An appreciable accumulation of the virus in the nasal cavity was coupled with weak interferon induction in this organ. On the other hand, a high level of interferon in the blood was concomitant with the development of slight sporadic viraemia.

[Study of the treatment-prophylactic effect of immunomodulators in experimental infections, caused by Marburg, Ebola, and Venezuelan equine encephalitis viruses]. / Izuchenie lechebno-profilakticheskogo deistviia immunomoduliatorov pri éksperimental'nykh infektsiiakh, vyzvannykh virusami Marburg, Ebola i Venesuél'skogo éntsefalomielita loshadei]

Therapeutic and prophylactic effects of immunomodifiers ridostin, reaferon, and polyribonate used alone and in various combinations were assessed in experiments on guinea pigs infected with Venezuelan equine encephalomyelitis (VEE) (strain Trinidad), Marburg (strain Popp), and Ebola (M/C-8 variant of Zaire strain) viruses at doses 5 to 20 respiratory LD50 through the respiratory airways. Urgent prophylactic simultaneous intramuscular and intranasal administration of ridostin protected the animals infected with Marburg virus (p = 0.1) and prolonged their life span by 2.4 days (p = 0.15). In Ebola infection a combination of ridostin and reaferon appreciably prolonged the mean life span: by 2.9 days (p = 0.04). In VEE ridostin alone or in combination with reaferone appreciably increased the share of survivors; ridostin with reaferon and polyribonate notably prolonged the mean life span of infected animals. None of these drugs or combinations produced an appreciable therapeutic effect in any of the studied infections.

[Survival of Marburg virus infectivity on contaminated surfaces and in aerosols]. / Sokhranenie infektsionnosti virusa Marburg na kontaminirovannykh poverkhnostiakh i v aérozole.

Marburg virus was shown to survive for up to 4-5 days on contaminated surfaces. In aerosol it was not stable, the specific rate of its inactivation being 0.05 min-1. This brought the authors to a conclusion that a relatively close contact is needed for virus transmission from man to man, although the possibility of aerosol transmission of the infection may be appreciably increased in case of the hemorrhagic syndrome with a high level of viremia.