Fil: Echeverria, Pablo C. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.Fil: Rojas, Paola A. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.Fil: Martin, Valentina. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.Fil: Guarnera, Eduardo. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.Fil: Pszenny, Viviana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.Fil: Ángel, Sergio O. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Parasitología. Departamento de Parasitología Sanitaria; Argentina.A novel Toxoplasma gondii interspersed repeat element (TgIRE), present in most of the tachyzoite chromosomes, was characterised. Two regions on the TgIRE sequence showed high identity to two different T. gondii expressed sequence tag cDNAs of unknown function, which seems to be TgIRE pseudogenes. Two set of primers were designed, 2-2' and 2-3, that amplify products of 1.02 and 0.62 kb, respectively. T. gondii DNA from RH and Me49 strains was amplified with TgIRE 2-2' primers, and the respective 1.02 kb products were digested with several endonucleases. Different fragment patterns by gel electrophoresis were found only with MboI. Sensitivity analysis revealed that the set 2-3 was more sensitive than 2-2', detecting by gel visualisation the amount of DNA equivalent to 1 and 10 parasites, respectively.