[Yersinia pestis factors, assuring circulation and maintenance of the plague pathogen in natural foci ecosystems. Report 1].

Everlasting reproduction of Yersinia pestis, plague bacillus in natural pestholes needs virulent causative agent to invade into the host entity, be potent to overcome protection powers of the rodent organism and to pullulate to entail bacteriemia for subsequent conveyance the plague bacillus to the new host by fleas. All of legs of life cyclic patterns of Yersinia pestis are maintained by a number of plague bacillus factors acting jointly or separately, participating at the different stages of infectious process or conveyance. However these factors provide the perpetuation of the plague bacillus in the ecosystems of natural pestholes only acting in conjunction independently on their distinct contributions. Not only biomolecules, organellas and bacteria systems ensured the pursuance of virulent properties, but other factors, essential for survival of Yersinia pestis and the relationship between separate virulence factors and expression of the different genes of housekeeping and virulence of plague bacillus are considered in this review. The report I covers the problems concerned with adaptational plasticity of Yersinia pestis, it represents the classification of plague causative factors, securing its perpetuation in the environmental space, and discussion the factors promoting plague bacillus survival in the host entity. Not only wellknown publications, but papers in out-of-the-way or hard-to-reach, especially for English-reading experts, editions, also were used to compile this communication. The English version of this review may be requested from Alerton Press.