Characteristics of Toxoplasma-gondii-tachyzoites from different culture systems

Toxoplasma gondii is an intracellular protozoan parasite of worldwide distr ibution. Parasites that habour a complete antigenic profile, that is necess ary for the serological diagnosis of human Toxoplasma infections, are provi ded 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 mos t laboratories the asexual proliferative stage of the parasite, the tachyzo ite, is maintained by successive intraperitoneal passages in highly suscept ible animals such as mice. We would like to develop an in vitro method to provide sufficient amounts o f high quality parasite antigen suitable for diagnosis of Toxoplasmosis. Us ing 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 clue to the in v itro culture conditions. Based on the result described previously the work could be continued as follows. One strategy could be to simulate the host i mmune pressure during the in vitro cultivation of the tachyzoites. A more c onvinced approach may be the production of recombinant parasite antigens us eful for diagnosis of a Toxoplasma infection in human adults and newborns.