Giardia intestinalis antigens expressed in Escherichia coli.

cDNA and genomic DNA of Giardia intestinalis have been cloned in pUC vectors and used to express Giardia antigens in Escherichia coli. Several expression libraries have been produced and positive clones identified by immuno-colony assays with antisera raised against whole parasites and partially purified antigen(s). Those clones which express G. intestinalis antigens have been used to raise antisera in mice and the antisera used in immunofluorescence assays. The proteins expressed by the clones have been shown to represent a 32 kDa protein of the flagellae and axonemes, a protein associated with the spiral part of the ventral disc, proteins covering the surface of the trophozoite or associated with the coat, and other proteins associated with axonemes of posterolateral flagellae, kinetosomes and funis, and the anterolateral axonemes. mRNA was purified from G. intestinalis and translated in a cell free lysate. A rabbit antiserum raised against trophozoites immunoprecipitated several translation products while an antiserum raised against a purified 32 kDa protein only immunoprecipitated this protein. G. intestinalis rRNA subunits also were examined in the course of mRNA purification. Two rRNA species were evident, the small rRNA and the post-transcriptionally processed large rRNA.