title: Comparison of virulence between the Yersinia pestis Microtus 201, an avirulent strain to humans, and the vaccine strain EV in rhesus macaques, Macaca mulatta.
abstract: Our previous study has demonstrated that Yersinia pestis Microtus 201 is a low virulent strain to the Chinese-origin rhesus macaques, Macaca mulatta, and can protect it against high dose of virulent Y. pestis challenge by subcutaneous route. To investigate whether the Y. pestis Microtus 201 can be used as a live attenuated vaccine candidate, in this study its intravenous virulence was determined and compared with the live attenuated vaccine strain EV in the Chinese-origin rhesus macaque model. The results showed that the Chinese-origin rhesus macaques can survive intravenous infection with approximately 10(9) CFU of the Y. pestis Microtus 201, but all the animals succumbed to 10(10) CFU of intravenous infection. By contrast, all the animals survive intravenous infection with 10(10) CFU of the vaccine EV. Post-mortem examination showed multiple areas of severe abscess in the lungs of the dead animals infected with 10(10) CFU of the Y. pestis Microtus 201, whereas histopathology observation, microbiological examination and immunohistochemistry staining showed that the Y. pestis Microtus 201 also invaded hearts, livers, spleens, kidneys and lymph nodes and caused different degrees of pathological changes in these organs. These results indicated that the Y. pestis Microtus 201 is indeed low virulent to monkeys, but it is more virulent than the vaccine EV when administered by intravenous route. The Y. pestis Microtus 201 mainly attack the lungs when administered by intravenous infection, which may be the leading cause of animal death.
authors.affiliation: a Laboratory of Analytical Microbiology; State Key Laboratory of Pathogen and Biosecurity; Beijing Institute of Microbiology and Epidemiology ; Beijing , China.
authors.forename: Guang
authors.initials: G
authors.lastname: Tian
authors.forename: Zhizhen
authors.initials: Z
authors.lastname: Qi
authors.forename: Yefeng
authors.initials: Y
authors.lastname: Qiu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wu
authors.forename: Qingwen
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Yang
authors.forename: Youquan
authors.initials: Y
authors.lastname: Xin
authors.forename: Jian
authors.initials: J
authors.lastname: He
authors.forename: Yujing
authors.initials: Y
authors.lastname: Bi
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Jiyuan
authors.initials: J
authors.lastname: Zhou
authors.forename: Yanxiao
authors.initials: Y
authors.lastname: Fan
authors.forename: Yazhou
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Jiang
authors.forename: Ruifu
authors.initials: R
authors.lastname: Yang
authors.forename: Xiaoyi
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D006801:Humans; D008253:Macaca mulatta; D010930:Plague / Q000473:pathology; D010931:Plague Vaccine / Q000276:immunology*; D014774:Virulence; D015010:Yersinia pestis / Q000472:pathogenicity*
chemical_list: D010931:Plague Vaccine
keywords: CFU, colony-forming units; HE, haematoxylin and eosin; i.n.,intranasal; i.v., intravenous; live attenuated vaccine; plague; protection; rhesus macaques; s.c., subcutaneous; yersinia pestis