Detection of Toxoplasma gondii antigens by a dot-immunobinding technique

A sensitive assay for the detection of antigens of Toxoplasma gondii by spotting samples directly onto nitrocellulose paper was developed. The sensitivity ranged from 10 to 40 pg of antigen diluted in phosphate-buffered saline and 40 to 130 pg of antigen diluted in normal mouse serum, normal human serum, or human cerebrospinal fluid. T. gondii antigen in serum samples taken from mice infected with T. gondii was detectable by day 2 of infection. Antigen was also detectable in cerebrospinal fluid samples taken from four of six infants congenitally infected with T. gondii and in serum samples from two of these infants.