The <i>Yersinia pestis</i> aggregation as a functional adaptation to the flea organism (review)

Abstract

The understanding of mechanisms and conditions of plague microbe aggregation in vectors (fleas) organisms has been of interest for a long time, and, with start of biofilm research in 1990s, it got a new perspectives. With the aim to determine the characteristics of the plague microbe aggregation in the organism the main vector in Tuva natural plague focus flea of Citellophilus tesquorum species, the data of many years of experimental studies focused on typical virulent strains of Yersinia pestis subsp. pestis were summarized and analyzed. Ectoparasites were infected and fed on long-tailed ground squirrel (Spermophilus undulatus), which is their natural host and main carrier of plague in Tuva natural plague focus. Interaction between Y. pestis and fleas were estimated using the rate of individuals with conglomerates bacterial lumps, formed during feeding, and blocks in the proventriculus foRmed during feeding and throughout the whole experiment registered in alive fleas after bloodsucking, and also using frequency of causative agent transmission to animals used for feeding. The analysis identified factors influencing the frequency and dynamics of different Y. pestis aggregate types forming into C. tesquorum, and suggest that these processes are functional adaptation of microbe to the flea organism.