Serology using rROP2 antigen in the diagnostic of toxoplasmosis in pregnant women

Abstract

SUMMARYToxoplasma gondii causes severe fetal disease during acute infection in pregnant women, thus demanding early diagnosis for effective treatment and fetus preservation. Fetal tests are inefficient and risky, and diagnosis is based on maternal IgM serology, which had weak screening ability due to increased sensitivity, with alternative IgG avidity tests. Here, we performed ELISA and avidity assays using a recombinant T. gondii antigen, rROP2, in samples from 160 pregnant women screened from a large public hospital who were referred due to positive IgM assays. IgG serology and avidity assays were compared using whole T. gondii extract or rROP2. ELISA IgG detection with rROP2 showed good agreement with assays performed with T. gondii extract, but rROP2 IgG avidity assays were unrelated to whole extract antigen IgG avidity, regardless of the chaotrope used. These data show that avidity maturation is specific to individual antigen prevalence and immune response during infection. ELISA rROP2 IgG assays may be an alternative serological test for the diagnosis of toxoplasmosis during pregnancy, although our data do not support their use in avidity assays.

Saliva as a source of anti-Toxoplasma gondii IgG for enzyme immunoassay in human samples

“…We used this population due to their availability for expanding saliva testing without attempting to detect IgG avidity or any other acute infection predictor. Our Dot-ELISA results are similar to those described in previous studies [10], in which anti-rubella IgG antibodies were detected in saliva, and the pioneering study in which anti-T. gondii antibodies were detected in saliva [6,11].…”

“…Many studies support the idea that in older volunteers, the rate of serological positivity for toxoplasmosis is greater [14]. Our results demonstrated a 19% frequency of serological positivity, which is lower than that demonstrated in other Brazilian studies; for example, a 50% frequency was observed in teenagers in low-income neighbourhoods in the same city [6], and a >70% frequency was observed in adults in the Brazilian Amazon [15]. We attributed the low frequency observed in our study to the high-income origin of our volunteers or university students.…”

Desenvolvimento de ensaios imunoenzimáticos para otimização da detecção de IgG anti - T.gondii em saliva humana

“…Several studies have examined the potential of saliva as a biological fluid for laboratory diagnostic tests [17]. Its was first used in diagnostic testing for monitoring drugs and hormones [8] and it was then applied in the diagnosis of infectious diseases of different origins such as fungal infections [10], parasitic diseases such as schistosomiasis [26], toxoplasmosis [14], neurocysticercosis [7]) and viral infections [20]. Saliva is a specific fluid secretion from salivary glands such as the parotid, submandibular, sublingual and minor glands, together with substances derived from the gingival crevicular fluid, bronchial secretions or nasal squamous epithelial cells, food debris, microorganisms and their metabolic products [11].…”

“…We Mice were supplied by our colony and T.gondii strains were cryopreserved at the laboratory as previously reported [14]. All chemicals and reagents were supplied by commercial sources unless specified.…”

“…All antigen preparation was performed on tachyzoites from RH strain obtained by peritoneal washings of infected mice and purified by centrifugation and filtration in polycarbonate filters for host cell removal as elsewhere reported [14] All reactions were performed with a large single round of antigen preparation…”