Simple and efficient method for measuring anti-toxoplasma immunoglobulin antibodies in human sera using complement-mediated lysis of transgenic tachyzoites expressing beta-galactosidase

A simple and efficient method using transgenic Toxoplasma gondii tachyzoite s expressing beta -galactosidase was developed for detection of specific an tibodies against the parasite in sera of patients, The titers obtained,vith the new test were similar to those obtained with the Sabin-Feldman dye tes t run in parallel. Although significant changes in endpoint titers were not observed when sera drawn sequentially at 2- to 3-week intervals were teste d with both procedures, apparent differences in antibody affinity were obse rved with the new test which were not perceptible with the Sabin-Feldman dy e test. Like the Sabin-Feldman dye test, the new test is based on complemen t lysis of tachyzoites, but it is much easier to perform and the reaction i s read colorimetrically instead of visually.