Detection of Toxoplasma gondii DNA by polymerase chain reaction in experimentally desiccated tissues.

Despite toxoplasmosis being a common infection among human and other warm-blooded animals worldwide, there are no findings about Toxoplasma gondii evolutionary forms in ancient populations. The molecular techniques used for amplification of genetic material have allowed recovery of ancient DNA (aDNA) from parasites contained in mummified tissues. The application of polymerase chain reaction (PCR) to paleoparasitological toxoplasmosis research becomes a promising option, since it might allow diagnosis, acquisition of paleoepidemiological data, access to toxoplasmosis information related origin, evolution, and distribution among the ancient populations. Furthermore, it makes possible the analysis of parasite aDNA aiming at phylogenetic studies. To standardize and evaluate PCR applicability to toxoplasmosis paleodiagnostic, an experimental mummification protocol was tested using desiccated tissues from mice infected with the ME49 strain cysts, the chronic infection group (CIG), or infected with tachyzoites (RH strain), the acute infection group (AIG). Tissues were subjected to DNA extraction followed by PCR amplification of T. gondii B1 gene. PCR recovered T. gondii DNA in thigh muscle, encephalon, heart, and lung samples. AIG presented PCR positivity in encephalon, lungs, hearts, and livers. Based on this results, we propose this molecular approach for toxoplasmosis research in past populations.