Recombinant antigens to detect Toxoplasma gondii-specific immunoglobulin Gand immunoglobulin M in human sera by enzyme immunoassay

We have evaluated the diagnostic utility of eleven Toxoplasma gondii recomb inant antigens (P22 [SAG2], P24 [GRA1], P25, P28 [GRA2], P29 [GRA7], P30 [S AG1], P35, P41 [GRA4], P54 [ROP2], P66 [ROP1], and P68) in immunoglobulin G (IgG) and IgM recombinant enzyme-linked immunosorbent assays (Rec-ELISAs). Following an initial evaluation, six recombinant antigens (P29, P30, P35, P54, P66, and P68) were tested in the IgG and IgM Rec-ELISAs with four grou ps of samples which span the toxoplasmosis disease spectrum (negative, chro nic infection, acute infection, and recent seroconversion). Our results sug gest that the combination of P29, P30, and P35 in an IgG Rec-ELISA and the combination of P29, P35, and P66 in an IgM Rec-ELISA can replace the tachyz oite antigen in IgG and IgM serologic tests, respectively. The relative sen sitivity, specificity, and agreement for the IgG P29-P30-P35 Rec-ELISA were 98.4, 95.7, and 97.2%, respectively. The resolved sensitivity, specificity , and agreement for the IgM P29-P35-P66 Rec-ELISA were 93.1, 95.0, and 94.5 %, respectively. Relative to the tachyzoite-based immunocapture IgM assay, the IgM P29-P35-P66 Rec-ELISA detects fewer samples that contain IgG antibo dies with elevated avidity from individuals with an acute toxoplasmosis.