Detection of Vibrio cholerae in nonculturable state by indirect immunofluorescent assay

Objective To develop a diagnostic test based on indirect immunoflourescent assay(IFA) to detect viable but nonculaurable state Vibrio cholerate O1 and O139.Methods Viable but nonculturable 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 isothiocyanate(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 10~4 cells/400ml.Conclusion The IFA method was sensitive and specific for detecting Vibrio cholerae in viable but nonculturable state,and was reliable for laboratory diagnosis of nonculturable state Vibrio cholerae that exist in natural water bodies,providing a effective tool for the ecological study of Vibrio cholerae.