Characterisation of Toxoplasma gondii isolates using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) of the non-coding Toxoplasma gondii (TGR)-gene sequences

The Toxoplasma gondii (TGR) genes constitute a family of non-coding sequenc es, three of which have been previously described as possible tools for typ ing of Toxoplasma gondii isolates. We obtained new isolates of T. gondii fr om domestic and wild animals, and used these to evaluate the possibility of using TGR gene variants as markers to distinguish among T. gondii isolates from different animals and different geographical sources. Based on the band patterns obtained by restriction fragment length polymorp hism (RFLP) analysis of the polymerase chain reaction (PCR) amplified TGR s equences, the T, gondii isolates could be separated into seven groups. Sequ encing the amplified products showed that at least 20 TGR sequences not hit herto described had been found, demonstrating that the TGR gene family comp rises a large number of different yet highly homologous sequences. Each iso late had its own unique TCR sequence. The TGR gene family therefore seems a promising target for typing individual T. gondii isolates and for studying the genetic distance between two isolates, which can be used for tracing r outes of infection. (C) 2000 Published by Elsevier Science Ltd. on behalf o f the Australian Society for Parasitology Inc. All rights reserved.