**Molecular Detection and Genotyping of** *Toxoplasma gondii* **from Clinical Samples**

Vladimir Ivović, Marija Vujanić, Tijana Živković, Ivana Klun and Olgica Djurković-Djaković

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/50830

#### **1. Introduction**

Over the past two decades, molecular diagnosis of toxoplasmosis, which is based on the detection of *T. gondii* DNA in clinical samples, became an indispensable laboratory test. This method is independent of the immune response, and depending on methodological approach, may facilitate more accurate diagnosis, especially in cases in which inadequacy of conventional methods is faced with deteriorating and potentially severe clinical outcome (congenital, ocular toxoplasmosis and cases of immunosuppression).

Molecular methods based on polymerase chain reaction (PCR) are simple, sensitive, reproducible and can be applied to all clinical samples (Bell and Ranford-Cartwright, 2002; Contini et al., 2005; Calderaro et al., 2006; Bastien et al., 2007). These methods are divided into two groups. The first group consists of techniques focused on detection of *T. gondii* DNA in biological and clinical samples, including conventional PCR, nested PCR and realtime PCR. The second group consists of molecular methods including PCR-RFLP, microsatellite analysis and multilocus sequence typing of a single copy *T. gondii* DNA and those are predominantly used for strain typing (Su et al., 2010).

However, it is important to emphasize that molecular diagnostics, being a constantly improving modern methodology, is not standardized even among the world's leading laboratories. The differences are substantial and numerous, and they extend to all segments of the methodology such as target genes for parasite detection and markers for genotyping, equipment manufacturers and different protocols (various sets of primers and probes and their concentration, different internal controls, etc...).

© 2012 Ivović et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
