Cell free synthesis of Toxoplasma gondii antigens.

Functionally active poly(A)-containing mRNA was isolated from tachyzoites of the RH strain of Toxoplasma gondii. The T. gondii mRNA was capable of directing the synthesis of proteins in a wheat germ in vitro translation system, but not in a cell free system derived from rabbit reticulocyte lysate. Efficient translation in the wheat germ system required spermine and exogenous tRNA. Amino acid incorporation was maximal at 110 mM K+ and 1.8 mM Mg2+. Tachyzoite antigens synthesized in vitro were immunoprecipitated with T. gondii antibodies from rabbits, mice and humans. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of immunoprecipitated polypeptides yielded patterns that differed according to antibody source, but all T. gondii antibody preparations reacted with a translation product with an apparent molecular weight of 24 000.