Comparison of Cryptosporidium-specific and Giardia-specific monoclonal antibodies for monitoring water samples

Routine detection of Cryptosporidium oocysts and Giardia cysts depend on immunofluorescence assays (IFA) employing fluorescently labeled monoclonal antibodies. Commercially available mAbs used for the detection of Cryptosporidium oocysts are of the IgM or IgG3 subclass, whilst those used for Giardia analysis are of IgM and IgG classes including IgG1. These mAbs suffer from non-specific binding to detrital particles present in environmental samples resulting in high levels of background fluorescence. New mAbs of the IgG1 subclass to Giardia and Cryptosporidium selected primarily for water analysis have recently become available. These antibodies exhibited lower levels of non-specific particulate binding compared with commercially available antibodies. The degree of background fluorescence observed following mAb staining of particles that were not oocysts or cysts varied between the water types analysed.