Preparation of Toxoplasma gondii RH strain antigen, antigen analysis and antigen detection in sera: a review.

The prevalence of antibodies detected by serology against Toxoplasma gondii in Indonesia is quite high. Therefore further research concerning the antigen used is important to improve the quality of the assay being used with lower cost. An attempt to prepare T. gondii strain RH antigen followed by using it in the ELISA procedure for detecting IgG showed that there was no significant difference between the local ELISA and Toxonostika quantitatively and qualitatively. Analysis of the antigen was done by Western blot, using sera collected from 30 clinically suspected toxoplasmosis cases which contained IgG only (titer ranging from 1:1,600-> or = 1:3,200); from 9 asymptomatic healthy person, from 5 cases consisted of 1 case of lymphadenitis (IgM titer > or = 1:3200 and IgG titer 1:800) and 4 cases of visual disturbances which had IgM with titer ranging from 1:800 to > or = 1:3,200 and IgG with titer ranging from 1:800 to > or = 1:3,200. It was shown that antigen components of 90, 87, 82, 72, 41, 26 and < or = 6 kDa reacted to all sera containing IgG except sera containing both IgG and IgM. Especially bands of 41 and 26 kDa showed strong reaction with all sera containing IgG, except 2 sera which contained both IgG (titer 1:800) and IgM (titer 1:800 and 1:3,200). These sera collected from 2 left eye vision disturbance cases were not reactive to all antigen components. Strong reactions against bands of 41, 26 and < or = 6 kDa were also shown in sera which contained only IgG collected from 9 healthy persons without any toxoplasmosis symptoms whereas bands of 90, 87, 82 and 72 kDa all showed moderate strong reaction. Contrasting to sera containing only IgG, of 5 sera containing both IgG and IgM 3 of them showed only reactions against bands of 41, 26 and < or = 6 kDa which were strong. It seemed that almost all sera containing IgG gave reaction to 90, 87, 82, 72, 41, 26 and < or = 6 kDa, however different pattern of reaction might occur, probably depending on the nature of infection as more antigen components would be recognized by sera containing IgG alone rather than sera containing both IgM in large quantity and IgG. In another study, an attempt to detect T. gondii antigen in 60 samples was done by using ELISA, and it was shown that circulating antigen was found in 27 (90%) from 30 samples which contained both IgG and IgM, whereas only 2 (66%) from 30 samples which contained only IgG showed positive results. Therefore, antigen detection can be used to identify the acute phase of infection.