Toxoplasmosis serology: an efficient hemagglutination procedure to detect IgG and IgM antibodies

Abstract

In search of an efficient but simple, low cost procedure for the serodiagnosis of Toxoplasmosis, especially suited for routine laboratories facing technical and budget limitations as in less developed countries, the diagnostic capability of Hematoxo® , an hemagglutination test for toxoplasmosis, was evaluated in relation to a battery of tests including IgG- and IgM-immunofluorescence tests, hemagglutination and an IgM-capture enzymatic assay. Detecting a little as 5 I.U. of IgG antitoxoplasma antibodies, Hematoxo® showed a straight agreement as to reactivity and non-reactivity for the 443 non-reactive and the 387 reactive serum samples, included in this study. In 23 cases presenting a serological pattern of acute toxoplasmosis and showing IgM antibodies, Hematoxo® could detect IgM antibodies in 18, indicated by negativation or a significant decrease in titers as a result of treating samples with 2-mercapto-ethanol. However, a neat increase in sensitivity for IgM specific antibodies could be achieved by previously removing IgG from the sample, as demonstrated in a series of acute toxoplasmosis sera. A simple procedure was developed for this purpose, by reconstituting a lyophilized suspension of Protein A - rich Staphylococcus with the lowest serum dilution to be tested. Of low cost and easy to perform, Hematoxo® affords not only a practical qualitative procedure for screening reactors and non-reactors, as in prenatal services, but also quantitative assays that permit to titrate antibodies as well as to identify IgM antibodies.

A novel igm‐indirect hemagglutination test for the serodiagnosis of acute toxoplasmosis

“…In group I , 91% of serum samples had significant titer decrease ( 2 three dilutions) after 2-ME treatment, as retested by the IHA test. Probably in the remainder 9% of sera which showed no titer decrease, high IgG antibody levels interfered, masking any titer decrease of IgM antibody ( 5 ) .…”

“…The M-Toxo-IHA test was carried out with the standardized reagent in V-shaped wells of plastic microplates as described (5,241, except that serum samples were diluted in 0.1 M NaCl.…”

“…For instance, the usual immunofluorescence (IgM-IF) test and the enzyme-linked immunosorbent assay (IgM-ELISA) require additional serum processings to block rheumatoid factor ( 2 ) or to remove IgG antibodies (3) in order to afford more sensitive and reliable results. On the other hand, the serum treatment with 2-mercaptoethanol (2-ME) used in the conventional indirect hemagglutination (IHA) test fails to detect low levels of IgM antibodies (4)(5)(6). To avoid such prior serum sample handlings, techniques such as IgMcapture based on immunoenzymatic or hemadsorption assays (7lo), as well as immunofiltration combined with immunoenzymatic assay ( 1 l ) , were devised.…”

Anatomopathological study in BALB/c mice brains experimentally infected with Toxoplasma gondii

“…gondii has been responsible for human infections with bad prognosis [11,12]. This infection can be experimentally induced in laboratory animals, especially mice [13][14][15][16]. Therefore the experimental infection has helped to understand the pathological and physiological aspects of this disease considered of great importance to humans.…”

Detection of anti-Toxoplasma gondii antibodies in experimentally and naturally infected non-human primates by Indirect Fluorescence Assay (IFA) and indirect ELISA

“…The IFA was performed as per as Camargo, Moura and Leser (1989). Two different conjugates were used: an anti-monkey IgG (Sigma Co., St. Louis, USA) at a 1:32 dilution and an anti-monkey IgM (KPL Inc., Gaithersburg, USA) at a 1:200 dilution, labeled with fluorescein isothiocyanate, both in phosphate buffered saline (PBS) containing 0.01% Evans Blue.…”