Bead capture and detection of Vibrio parahaemolyticus

A novel method was developed for rapid detection of Vibrio parahaemolyticus with immunomagnetic separation followed by PCR.Whole cells of V.parahaemolyticus were used as antigen for polyclonal antibody (pAb) production in rabbit.Titers of pAb were detected by enzyme-linked immunosorbent assay (ELISA) .Antiserum was purified with ammonium sulfate precipitation and reverse adsorption, purity and specificity of the resulted pAb was tested with SDS-PAGE and dot-blot hybridization.Purified pAb was conjugated with magnetic beads for bacteria separation.Results showed that the titer of purified antibody was 106 , and the capture rates of immunomagnetic beads were between 55%～70% under different conditions.Salt concentration and pH had only slight influence on the capture rate.The limit of detection ( LOD) of the method was 102 cfu/mL in pure culture and 103 cfu/mL in fish paste samples (in presence of other kinds of bacteria species ) . In conclusion, combined immunomagnetic separation with PCR for the detection of V.parahaemolyticus has high sensitivity and specificity, which is promising for in-field detection.