[EVALUATION OF THE HUMAN SENSITIVITY TO SMALLPOX VIRUS BY THE PRIMARY CULTURES OF THE MONOCYTE-MACROPHAGES].

Studies of the primary cultures of granulocytes, mononuclear, and monocyte-macrophage cells derived from human blood were performed using variola virus (VARV) in the doses of 0.001-0.021 PFU/cell (plaques-forming units per cell). Positive dynamics of the virus accumulation was observed only in the monocyte-macrophages with maximum values of virus concentration (5.0-5.5 Ig PFU/ml) mainly within six days after the infection. The fact of VARV replication in the monocyte-macrophages was confirmed by the data of electron microscopy. At the same time, virus vaccines when tested in doses 3.3 and 4.2 Ig PFU/ml did not show the ability to reproduce in these human cells. The people sensitivity to VARV as assessed from the data obtained on human monocyte-macrophages corresponded to -1 PFU (taking into account the smooth interaction of the virus in the body to the cells of this type), which is consistent to previously found theoretical data on the virus sensitivity. The human susceptibility to VARV assessed experimentally can be used to predict the adequacy of developed smallpox models (in vivo) based on susceptible animals. This is necessary for reliable assessment of the efficiency of development of drugs for treatment and prophylaxis of the smallpox.

[THE USE OF THE MODEL MOUSE ICR--VARIOLA VIRUS FOR EVALUATION OF ANTIVIRAL DRUG EFFICACY].

Mice of the ICR outbred population were infected intranasally (i/n) with the variola virus (VARV, strain Ind-3a). Clinical signs of the disease did not appear even at the maximum possible dose of the virus 5.2 lg PFU/head (plaque-forming units per head). In this case, 50% infective dose (ID50) of VARV estimated by the presence or absence of the virus in the lungs three days after infection (p.i.) was equal to 2.7 ± 0.4 lg PFU/head. Taking into account the 10% application of the virus in the lungs during the intranasal infection of the mice, it was adequate to 1.7 lg PFU/lungs. This indicates a high infectivity of the VARV for mice comparable to its infectivity for humans. After the i/n infection of mice with the VARV at a dose 30 ID50/ head the highest concentration of the virus detected in the lungs (4.9 ± 0.0 lg PFU/ml of homogenate) and in nasal cavity tissues (4.8 ± 0.0 lg PFU/ml) were observed. The pathomorphological changes in the respiratory organs of the mice infected with the VARV appeared at 3-5 days p.i., and the VARV reproduction noted in the epithelial cells and macrophages were noticed. When the preparations ST-246 and NIOCH-14 were administered orally at a dose of 60 µg/g of mouse weight up to one day before infection, after 2 hours, 1 and 2 days p.i., the VARV reproduction in the lungs after 3 days p.i. decreased by an order of magnitude. Thus, outbred ICR mice infected with the VARV can be used as a laboratory model of the smallpox when evaluating the therapeutic and prophylactic efficacy of the antismallpox drugs.

[Development of the disease in marmot at the intranasal infection with the monkeypox virus].

In experimental study the sensitivity of the Marmota bobak species to the monkeypox virus (MPXV) with the intranasal (i/n) infection was tested. It was demonstrated that 50% of the infective dose (ID50) of the MPXV on external clinical signs of the disease was 2.2 Ig plaque forming units (PFU). The percentage of the marmot mortality is slightly dependent on the infecting dose of the MPXV, therefore it is not possible to correctly determine the value of 50 % fatal dose (FD50) for these animals. The most pronounced external clinical signs of the disease were obtained in the marmots: pox-like skin rash throughout the surface of the body and mucous membranes, purulent discharge from the nose, lymphadenitis, discoordination, tremor of the extremities, fever, increased aggression, and ruffled fur. In the course of experiments intended to determine the dynamics of the accumulation of the MPXV in various organs, tissues, and blood serum of marmot infected i/n with dose of 3.7 Ig PFU, it was found that the trachea, lungs, and the bifurcation lymph nodes are the primary target organs. The trachea, lungs, nasal mucosa membrane, and skin are the organs with maximal virus replication recorded at 5, 7, 9, and 12 days after the infection. The transfer of the MPXV into the secondary target organs (nasal mucosa membrane, brain, spleen, duodenum, adrenal glands, and skin) was carried out in marmots with lymphogenic and hematogenic ways of the dissemination of the infection.