en زیست شناسی ملکولی Molecular Biology مقالات اصلی Original Article <div style="text-align: justify;"><strong><em>Background:</em></strong> <em>Leishmania (L)</em> <em>major</em> and <em>L. tropica</em> are the etiological agents of cutaneous leishmaniosis. <em>Leishmania</em> species cause a board spectrum of phenotypes. A small number of genes are differentially expressed between them that have likely an important role in the disease phenotype. Procyclic and metacyclic are two morphological promastigote forms of <em>Leishmania </em>that express different genes. The <a name="_Hlk34179449">glutathione peroxidase</a> is an important antioxidant enzyme that essential in parasite protection against oxidative stress and parasite survival. This study aimed to compare glutathione peroxidase (TDPX) gene expression in procyclic and metacyclic and also interspecies in Iranian isolates of <em>L. major </em>and<em> L. tropica. </em><br> <br> <strong><em>Methods:</em></strong> The samples were cultured in Novy-Nicolle-Mc Neal medium to obtain the promastigotes and identified using PCR-RFLP technique. They were then grown in RPMI1640 media for mass cultivation. The expression level of TDPX gene was compared by Real-time PCR.<br> <br> <strong><em>Results:</em></strong> By comparison of expression level, up-regulation of TDPX gene was observed (5.37 and 2.29 folds) in <em>L. major </em>and<em> L. tropica </em>metacyclic compared to their procyclic<em>, </em>respectively<em>.</em> Moreover, there was no significant difference between procyclic forms of isolates, while 3.05 folds up-regulation in metacyclic was detected in <em>L. major</em> compared <em>L. tropica</em>.<br> <br> <strong><em>Conclusions:</em></strong> Our data provide a foundation for identifying infectivity and high survival related factors in the <em>Leishmania </em>spp. In addition, the results improve our understanding of the molecular basis of metacyclogenesis and development of new potential targets to control or treatment and also, to the identification of species-specific factors contributing to virulence and pathogenicity in the host cells.</div> Glutathione peroxidase, Leishmania, L. major, L. tropica, Quantitative Real-time PCR. 324 330 http://rbmb.net/browse.php?a_code=A-10-296-2&slc_lang=en&sid=1 Nasrin Amiri-Dashatan 100319475328460017679 100319475328460017679 No Proteomics Research Center, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mehdi Koushki 100319475328460017680 100319475328460017680 No Department of Clinical Biochemistry, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran. Mostafa Rezaei-tavirani 100319475328460017681 100319475328460017681 No Proteomics Research Center, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Nayebali Ahmadi nayebalia@sbmu.ac.ir 100319475328460017682 100319475328460017682 Yes Proteomics Research Center, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran & Department of Medical Lab Technology, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.