Toxoplasma antigens recognized by immunoglobulin G subclasses during acute and chronic infection

Abstract

The immunoglobulin G (IgG) subclass response to Toxoplasma gondii antigens during the acute and chronic stages of T. gondii infection were studied by using immunoblots with reduced antigen (RA) and nonreduced antigen (NRA) preparations. Serum samples were from individuals with acute or chronic T. gondii infection, and sequential samples were from women who seroconverted during gestation and were treated with spiramycin. IgGl antibodies were predominant in sera from each of the groups and recognized a large number of RA and NRA. In the latter group of patients, IgGl and IgG3 were the first antibodies to appear in response to the infection. In all groups, an antigen with a molecular weight (MW) of 30,000 was the most intensely stained and frequently recognized by IgGl antibodies in NRA preparations. In RA preparations, antigens of MW 35,000 and 30,000 were the most intensely stained and frequently recognized by IgG1 antibodies. An antigen with an MW of 22,000 was intensely stained in the IgGl immunoblots of the NRA preparation and to a lesser extent in the RA preparation. In contrast to immunoblots with IgGl antibodies, very few antigens in the RA and NRA preparations were detected by IgG2 and IgG3 antibodies; IgG4 antibodies rarely detected any antigens. Of interest was that IgG2 antibodies detected antigens distributed over the entire MW range, whereas those detected by IgG3 antibodies were located mostly below the 35,000 MW marker. Enzyme-linked immunosorbent assay results paralleled those of the immunoblots in that IgGl antibodies were predominant.

Emergence of cutaneous neosporosis in a dog receiving immunosuppressive therapy: molecular identification and management

“…At another laboratory (IDEXX) a negative IgM (cut‐off = 1:16) and a low positive IgG titre of 1:128 (cut‐off = 1:64) against T. gondii tachyzoites (Toxo Spot IF, bioMérieux; Nurtingen, Germany) were detected. An in‐house IFA and immunoblot method with whole antigen for T. gondii at FLI was also low positive (low IFA titre of 1:25 and only three of five bands within the immunoblot – namely the 30, 35 and 45 kDa antigens; the 6 and 83 kDa antigens were not recognized, as previously reported) …”

Anti-P30 IgA antibodies as prenatal markers of congenital toxoplasma infection

“…If specific IgM alone is detected, the analysis of a second sample after 3 further weeks of evolution will confirm (presence of IgA) or not (absence oflgA) the possibility of a recent infection and, when specific IgM and IgA are simultaneously detected, the patient must be considered to be in the course of acute toxoplasmosis. As shown by the number of studies focused on the subject [10,[18][19][20][21][22], the early diagnosis of acute toxoplasmosis in pregnancy is of utmost importance. Indeed, pregnancy and fetal management are very different depending on whether the acute phase occurred after the date of conception, when the risk of fetal infection exists, or before the date of conception [5,23,24].…”

Differential agglutination test for diagnosis of recently acquired infection with Toxoplasma gondii

“…Their results suggest that the IgG antibodies present during the acute phase of infection in humans are directed against a surface antigen that is recognized by monoclonal antibody lE11. In separate studies, Derouin et al (3) and Huskinson et al (12) have reported that IgGl antibodies are the predominant IgG antibody subclass present in sera from patients with both recently acquired and chronic toxoplasma infections (3,12).…”