Distribution of Tryptophan-Dependent <I>Yersinia pestis</I> Variants in the Altai Mountain Natural Plague Focus
Carried out is the analysis of spatial location of tryptophan-dependent variants of plague microbe in the territory of Altai mountain plague natural focus. 1166 <I>Y. pestis</I> strains isolated in 1990–2010, were studied as regards nutrient requirements. 140 of them (12 %) were determined as tryptophan-dependent. The highest occurence of such strains was registered in Ulandryk focal region (21.6 % in average). Among strains isolated in Tarkhatin focal region only 2.3 % were tryptophan-dependent, and in Kuray region they were absent. Thus, the data obtained suggest that spatial heterogeneity of <I>Y. pestis subsp. altaica </I>in the focus takes place.