The glucose-6-phosphate dehydrogenase (Zwf) activity in Yersinia pestis subsp. pestis и Yersinia pestis subsp. altaica with different plasmid specrtrum was evaluated. Different levels of Zwf activity was observed in all strains of Y. pestis that were taken to experiment. Virulent Yersinia pestis subsp. pestis possess minimal index Zwf activity. The dynamics of Zwf activity in peritoneal macrophages of guinea pigs in contact with Yersinia pestis subsp. pestis и Yersinia pestis subsp. altaica was investigated in vitro. Increasing activity of Zwf at peritoneal macrophages are phagocytising plague agent was depending of plasmid compound of Yersinia pestis.