Detection of Vibrio cholerae in nonculturable state by indirect immunofluorescent assay

  Objective   To develop a diagnostic test based on indirect immunoflour escent assay(IFA)to detect viable but nonculaurable state Vibrio cholerate O1 and O 139.

  Methods   Viable but no nculturable state(VBNC)Vibrio cholerae transformed artificially in our laboratory were utilized as antigen on slide.Mixed diagnostic antisera(against serotype O1 and O139) was employed as direct antibody and fluorescein isothiocy anate(FITC)conjugated antibody to rabbit IgG as indirect antibody in IFA.

  Results   This method could detect viable but nonculturable state Vibrio cholerae in water successfully, and the low limit of detection was 10⁴ cells/400ml.

  Conclusion   The IFA method was sensitive and specific for detecting Vibrio choler ae in viable but nonculturable state, and was reliable for labor atory diagnosis of nonculturable state Vibrio cholerae that exist in natural water bodies, providing a effective tool for the ecological study of Vibrio cholerae.