ALTEX :: Alternatives to Animal Experiments

1998, Supplement

Characteristics of Toxoplasma-Gondii-Tachyzoites from Different Culture Systems

Harald Klein¹, Martina Anduleit¹, Monika Bornhak¹, Matthias Fischer¹, Uwe Gross², Bettina Loeschner¹, Sven Nicol¹, Ingrid Reiter-Orwona³, Nadja Zyto¹, and Thomas Montag-Lessing¹

¹Paul-Ehrlich-Institut, D-Langen; ²Institut für Hygiene und Mikrobiologie der Universitaet, D-Wuerzburg; ³Institut für Medizinische Parasitologie der Universitaet D-Bonn

SUMMARY

Toxoplasma gondii is an intracellular protozoan parasite of worldwide distribution. Parasites that habor a complete antigenic profile, that is necessary for the serological diagnosis of human Toxoplasma infections, are provided by in vivo culture methods only. It seems that the host immune pressure is responsible for the expression of a total antigen pattern. Thus, in most laboratories the asexual proliferative stage of the parasite, the tachyzoite, is maintained by successive intraperitoneal passages in highly susceptible animals such as mice.

We would like to develop an in vitro method to provide sufficient amounts of high quality parasite antigen suitable for diagnosis of Toxoplasmosis. Using the RAPD-PCR (random amplified polymorphic DNA-PCR) technique, we were able to show that during different culture conditions (in vivo and in vitro culture) the parasites undergo no clonal selection. That means the entire parasite population changes the protein expression pattern due to the in vitro culture conditions. Based on the result described previously, the work could be continued as follows. One strategy could be to simulate the host immune pressure during the in vitro cultivation of the tachyzoites. A more convinced approach may be the production of recombinant parasite antigens useful for diagnosis of a Toxoplasma infection in human adults and newborns.

Keywords: toxoplasma gondii, antigen pattern, random amplified polymorphic DNA-PCR, recombinant parasite antigens