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Open Access Research article

Sequence polymorphisms of rfbT among the Vibrio cholerae O1 strains in the Ogawa and Inaba serotype shifts

Weili Liang12, Luxi Wang13, Pu Liang12, Xiao Zheng1, Haijian Zhou1, Jingyun Zhang12, Lijuan Zhang1 and Biao Kan12*

Author Affiliations

1 State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, 102206, People’s Republic of China

2 Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, People’s Republic of China

3 Present address: Changping Center for Disease Control and Prevention, Beijing, People’s Republic of China

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BMC Microbiology 2013, 13:173  doi:10.1186/1471-2180-13-173

Published: 26 July 2013

Abstract

Background

Vibrio cholerae serogroup O1 has two major serotypes, Ogawa and Inaba, which may alternate among cholera epidemics. The rfbT gene is responsible for the conversion between the two serotypes. In this study, we surveyed the sequence variance of rfbT in the Ogawa and Inaba strains in China over a 48-year (1961-2008) period in which serotype shifts occurred among epidemic years.

Results

Various mutation events including single nucleotide, short fragment insertions/deletions and transposases insertions, were found in the rfbT gene of the Inaba strains. Ectopically introducing an intact rfbT could overcome the mutations by converting the Inaba serotype to the Ogawa serotype, suggesting the effects of these mutations on the function of RfbT. Characteristic rfbT mutations were recognized in the Inaba strains among Inaba serotype dominant epidemic years which were separate from the Ogawa dominant epidemics. Three distinguishable mutation sites in rfbT between the classical and the El Tor biotype strains were identified and could serve as biotype-specific biomarkers.

Conclusions

Our results provide a comprehensive picture of the rfbT gene mutations among the V. cholerae O1 strains in different epidemic periods, which could be further used as the tracing markers in clonality analysis and dissemination surveillance of the epidemic strains.