An atypical enzootic variant. Yersinia pestis Pestoides A

Yersinia pestis Pestoides A. Pestoides A is an atypical enzootic or nonepidemic 'pestoides' variant of Yersinia pestis probably acquired by the US from the USSR in the 1960s or 1970s. The strain is closely related to Pestoides B-D and likely these strains are sub-species altaica according to Anisimov et al. (2007), versus the sequenced Pestoides F strain which is subspecies caucasica. These atypical Y. pestis variants are considered important for understanding the evolution of acute virulence because they share characteristics of close relative Yersinia enterocolitica, a nonlethal enteric pathogen.