Evolution of IgG antibody response against Toxoplasma gondii tissue cyst in acute and chronic human infections

Abstract

The recognition profile of the tissue cysts antigens by IgG antibodies was studied during acute and chronic human toxoplasmic infection. Thus the IgG response against Toxoplasma gondii was investigated by immunoblotting in two patients accidentally infected with the RH strain as well as in group of naturally infected patients at acute and chronic phase. There was an overall coincidence of molecular mass among antigens of tachyzoites and tissue cysts recognized by these sera, however, they appear not to be the same molecules. The response against tissue cysts starts early during acute infection, and the reactivity of antibodies is strong against a wide range of antigens. Six bands (between 82 and 151 kDa) were exclusively recognized by chronic phase sera but only the 132 kDa band was positive in more than 50% of the sera analysed. A mixture of these antigens could be used to discriminate between the two infection phases. The most important antigens recognized by the acute and the chronic phase sera were 4 clusters in the ranges 20-24 kDa, 34-39 kDa, 58-80 kDa and 105-130 kDa as well as two additional antigens of 18 and 29 kDa. Both accidentally infected patients and some of the naturally infected patients showed a weak specific response against tissue cyst antigens.

Some Immunologic Evaluations of Toxoplasmosis in Iraqi Aborted Females

“…These cells showed a significant increase when the comparison made with healthy females (Control II), and such increase was paralleled by a significant increase in the serum level of IgG, but not IgA or IgM. Again, these findings confirm the chronic state of toxoplasmosis in the present patients, and evidences in laboratory animals and human support such task (22,23).…”

Sequential recognition of antigenic markers of Toxoplasma gondii tachyzoite by pooled sera of mice with experimental toxoplasmosis

“…It can be considered a good diagnostic marker for the acquisition of Toxoplasma infection but of no discriminative value between recent and latent infections in mice (El-Shenawy et al 2000;Fux et al 2000) or in humans (Marcolino et al 2000). This is in contrast to the work of Villavedra et al (1998) who reported this band as a good marker for IgG avidity maturation. Moreover, Pfrepper et al (2005) used recombinant antigen through ELISA technique for their avidity test on human sera and found that the recombinant SAG1 antigen was recognized with high-avidity IgG with chronic sera only.…”