High prevalence and diversity of pre-CTXΦ alleles in the environmental Vibrio cholerae O1 and O139 strains in the Zhujiang River estuary

Authors

  • Duochun Wang,

    1. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
    2. Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Guangzhou, China
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    • These authors contributed equally to this work.
  • Xiaomei Wang,

    1. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
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    • These authors contributed equally to this work.
  • Baisheng Li,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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    • These authors contributed equally to this work.
  • Xiaoling Deng,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Hailing Tan,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Baowei Diao,

    1. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
    2. Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Guangzhou, China
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  • Jingdiao Chen,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Bixia Ke,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Haojie Zhong,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Haijian Zhou,

    1. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
    2. Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Guangzhou, China
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  • Changwen Ke,

    1. Center for Disease Control and Prevention of Guangdong Province, Guangzhou, China
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  • Biao Kan

    Corresponding author
    1. National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, State Key Laboratory for Infectious Disease Prevention and Control, Beijing, China
    2. Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Guangzhou, China
    • For correspondence. E-mail kanbiao@icdc.cn; Tel. (+86) 10 58900744; Fax (+86) 10 58900742.

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Summary

Toxigenic conversion of environmental Vibrio cholerae strains through lysogenic infection by the phage CTXΦ is an important step in the emergence of new pathogenic clones. The precursor form of the CTXΦ phage, pre-CTXΦ, does not carry the cholera toxin gene. During our investigation, we frequently found pre-CTXΦ prophages in non-toxigenic isolates in the serogroups of O1 and O139 strains in the Zhujiang estuary. We observed high amounts of sequence variation of rstR and gIIICTX in the pre-CTXΦ alleles as well as in the tcpA sequences within the strains. In addition, a new pre-CTXΦ allele, with a novel rstR sequence type and hybrid RS2, was identified. Our findings show that active, complicated gene recombination and horizontal transfer of pre-CTXΦs occurs within V. cholerae environmental strains, which creates a complex intermediate pool for the generation of toxigenic clones in the estuarine environment.

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