Human antibody response to the nucleoside triphosphate hydrolase of Toxoplasma gondii.

An enzyme-linked immunosorbent assay (ELISA) that uses a recombinant protein of Toxoplasma gondii as antigen was used for the detection of specific antibodies in human sera. An antigenic portion of the T. gondii nucleoside triphosphate hydrolase (NTPase) was expressed in Escherichia coli as a glutathione S-transferase fusion protein with an apparent molecular mass of about 5000. A total of 118 T. gondii positive and 63 negative sera were examined. Seven % of the T. gondii positive sera, but none of the negative sera, reacted with the recombinant NTPase. Advantages and disadvantages that are associated with the use of fusion proteins as antigens in ELISA are discussed.