Phylogenetic study of the protozoan Toxoplasma gondii using cytochrome b and GRA20 genes

Toxoplasma gondii is an obligate intracellular protozoan in the phylum Apicomplexa. In addition to humans, toxoplasmosis can cause serious diseases in livestock, leading to significant economic losses. The use of molecular methods with high sensitivity has made it possible to detect and study microorganisms. In this study, the cytochrome b and dense granule 20 (GRA20) genes were utilized for studying Toxoplasma gondii parasites. After collecting 29 animal samples of Toxoplasma gondii, the PCR method was applied to evaluate the presence of GRA20 and cytochrome b genes. The sequences of 11 samples were acceptable and submitted to the NCBI database. MEGA X software was utilized to create the phylogenetic tree. In addition, genetic diversity was studied using the RFLP-PCR assay for the GRA6 gene. Assessment of the bands obtained from PCR showed that the bands related to cytochrome b are found in all species of the Sarcocystidae family, but the bands related to the GRA20 gene are specific to Toxoplasma gondii. In the phylogenetic tree, there was a closer relationship between Iranian isolates of Toxoplasma gondii and the French strain of Toxoplasma gondii. Type I was determined as the genetic type of the protozoan Toxoplasma gondii isolated from Iran. Based on the results, the cytochrome b gene was considered a general gene for recognizing different species of the Sarcocystidae family; however, divergence was seen in the GRA20 gene, which is considered a particular gene for Toxoplasma gondii.