[Relationships of the plague pathogen and vector from different parasitic systems]

The specific features of interaction of the strains of the plague microbe of the main subspecies, which circulate in the area of natural foci of Mongolia and China, with Citellophilus tesquorum sungaris fleas, the major vector of the plague pathogen in a Transbaikalian natural focus, as well as with Xenopsylla cheopis ones, the classical vector, were revealed. Experiments used virulent Yersinia pestis strains, such as I-3230 isolated from C.tesquorum in Mongolia in 1998 and 2155 isolated from humans in Manchuria (China) in 1947. They established that ectoparasites from other parasitic systems could transmit these strains. At the same time, the Y.pestis strain 1-3230 far exceeded the strain 2155 in its ability to form conglomerates as lumps. It is possible that this fact reflects the adaptive peculiarity of the Y.pestis strain 1-3230 to remain long (during the cold period of a year) in the flea C.tesquorum sungaris that survives winters mainly in the imago stage. The strain 2155 was more active in forming proventricular blocks in the body of X.cheopis, the blocking period in the latter was 3-7 times shorter than that in C.tesquorum sungaris when infected with both strains.