Comparison of a Nucleic Acid Sequence-based Amplification (NASBA) and real-time reverse transcriptase PCR methods for detection of Toxoplasma gondii in rat blood samples

The numbers of RNA amplification methods for detection of Toxoplasma spp. are increasing, however comparative studies on the performance of these different assays are lacking. The aim of this study was to compare two molecular assays for detection and quantification of Toxoplasma spp. in blood samples collected from experimentally infected rats. A set of specific primers and beacon probe were selected from the B1 rRNA gene of Toxoplasma. The assays using real-time detection proved to be both sensitive and specific. Nucleic acid sequence-based amplification (NASBA) method for detection of Toxoplasma spp. have advantages regarding sensitivity and potential quantitative population dynamics of Toxoplasma gondii in comparison with the RT-PCR method, but it is not often routinely used at present. NASBA had a detection limit of 1 parasite/ml of blood, while RT-PCR detected 10 parasites/ml. The results of real-time NASBA can be obtained 12h earlier. Therefore, sooner than the ordinary real-time RT-PCR the use of real-time NASBA is preferred to the ordinary real-time RT-PCR.