BIOTINYLATION A FAST AND REPRODUCIBLE METHOD FOR LABELING TRYPANOSOMA-CRUZI CELL-SURFACE PROTEINS

In this study we describe a simple and rapid method that uses sulfo-N- hydroxy-succinimidobiotin (sulfo-NHS-biotin) to label Trypanosoma cruz i surface proteins stably without significant loss of biological funct ion. Efficient labelling can be obtained with as little as a 5 minute incubation of parasites in an appropriate concentration of sulfo-NHS-b iotin at 4-degrees-C. After labelling under these conditions, biotinyl ated parasites exhibited levels of motility, viability, and in vivo in fectivity comparable to those seen with unlabelled control parasites. Moreover, the biological activity of T-DAF, a complement regulatory pr otein found on the parasite surface, was unaffected when biotinylated under these conditions. Biotinylated surface proteins can be easily de tected in a variety of non-radioactive assays employing conjugated str eptavidin as a developer. Compared to alternative techniques of surfac e labelling described in the literature, this method offers better pre servation of biological function as well as greater ease of use and sa fety.