RIBOSOMAL-RNA SEQUENCES FOR THE SPECIFIC DETECTION OF TOXOPLASMA-GONDII BY HYBRIDIZATION ASSAY

We describe the development of five oligonucleotide probes which target the small sub-unit rRNA of Toxoplasma gondii. These probes bind to different regions within the rRNA and all were effective in producing a detectable signal with as little as 10 ng of total cellular RNA. One probe in particular, TGB, was able to detect as little as 1 ng of RNA and was the most specific. A sixth probe, previously developed for hybridization with Sarcocystis spp., was evaluated for its specificity and was shown to be useful as a multi-species coccidial probe. Four of the five T. gondii-specific probes did not cross-hybridize with RNA from nine related species of coccidia, Escherichia coli, cattle, people, cat or dog. One probe cross-hybridized strongly with RNA of Eimeria ahsata and Isospora suis, but not to RNA of any other coccidia species tested nor bovine, human, feline or canine RNA. The potential of this assay for use in veterinary and human medicine as well as food safety programmes is discussed. © 1993 Academic Press Limited.