Utility of the cytochrome c oxidase subunit I gene for the diagnosis of toxoplasmosis using PCR.

Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii, which belongs to the phylum Apicomplexa. Since this parasite causes severe clinical symptoms in immunocompromised patients, early diagnosis of toxoplasmosis is essential. PCR is currently used for early diagnosis, but there is no consensus regarding the most effective method for amplifying Toxoplasma DNA. In this study, we considered the utility of the cytochrome c subunit I (cox1) gene, which is encoded in the mitochondrial DNA of this parasite, as a novel target of PCR for the diagnosis of toxoplasmosis. To do this, we compared its copy number per haploid nuclear genome and the detection sensitivity of cox1-PCR with the previously reported target genes B1 and 18S rRNA and the AF146527 repeat element. We found that the copy number of cox1 was high and that the PCR using cox1 primers was more efficient at amplifying Toxoplasma DNA than the other PCR targets examined. In addition, PCR using clinical samples indicated that the cox1 gene would be useful for the diagnosis of toxoplasmosis. These findings suggest that use of cox1-PCR would facilitate the diagnosis of toxoplasmosis in clinical laboratories.