Dot-ELISA for the detection of IgM and IgG antibodies to Schistosoma mansoni worm and egg antigens, associated with egg excretion by patients

Abstract

Human schistosomiasis, caused by Schistosoma mansoni, is highly prevalent in Brazil and usually diagnosed by time consuming stool analysis. Serological tests are of limited use in this disease, mainly for epidemiological studies, showing no discrimination between previous contact with the parasite and active infections. In the present study, we standardized and compared a Dot-ELISA for IgM and IgG antibodies against S. mansoni antigens from eggs and worms with a routine IgG and IgM immunofluorescence assay using similar antigens, in the study of sera from 27 patients who had quantified egg stool excretion. The positivity obtained for IgG Dot-ELISA was 96.3% and 88.9% for IgM Dot-ELISA with worm antigen and 92.6% and 90.9% with egg antigen. The IFI presented similar positivities using worm antigen, 92.6% (IgG) and 96.3% (IgM),and lower results with egg antigen, 77.8% (IgG and IgM). The patients studied were divided into two groups according to their egg excretion, with greater positivity of serological tests in higher egg excreters. When comparing the quantitative egg excretion and the serological titers of the patients, we detected a correlation only with IgM Dot-ELISA, with r=0.552 (p=0.0127). These data show that Dot-ELISA can be used for the detection of specific antibodies against S. mansoni in sera from suspected patients or in epidemiological studies and, with further purification of egg antigen and larger samples, IgM Dot-ELISA could be a possible tool for rough estimates of parasite burden in epidemiological studies.

Evaluation of microscopical and serological techniques in the diagnosis of Schistosoma mansoni infection at Sennar State, Central Sudan

“…Earlier in a study in Ethiopia, the sensitivity and specificity of the ELISA test were 97.6% and 30.3%, respectively [29] . Despite the serological tests like ELISA are not able to discriminate between previous contact with the parasite and active infections [30] , the high sensitivity ELISA has indicated this technique as one of the most successful serological tests for epidemiological studies to detect parasite burden [30,31] . In areas of endemicity, other researchers have suggested to carry out serological tests that require high specificity to avoid false-positive results.…”

“…An exactly 100 µL of the positive and negative controls and the diluted samples were dispensed on their corresponding wells, then the strip was covered with a foil and then incubated in an ELISA incubator at 37 °C for 1 h. The foil was removed, aspirated the content of all wells and washed five times with a 300 µL diluted washing solution and the remaining solution was removed carefully by tapping the plate on a tissue paper. Then 100 µL of protein a conjugate was added to all wells except the blank well and then the plate was covered with a foil and incubated at room temperature for 30 min. By the end of the second incubation, the plate again was washed five times with the diluted washing buffer, and then 100 µL of the solution was dispensed to all wells and then incubated for 15 min at room temperature in dark.…”

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

“…The main tool used for the diagnosis of toxoplasmosis is serology, and several serum tests were recommended for the diagnosis of toxoplasmosis [4]. The Dot-ELISA has been described as an efficient diagnostic method for infectious parasitic diseases such as Cutaneous Leishmaniasis [25], schistosomiasis [21], toxoplasmosis [18],and angiostrongyliasis [6].…”

Imunoproteômica aplicada ao aprimoramento do diagnóstico sorológico da estrongiloidíase humana

“…O DOT ELISA foi realizado de acordo com Pinto et al (1995) com algumas modificações. Previamente a aplicação de todas as amostras de soro foi realizado uma padronização com diferentes diluições do soro e do conjugado.…”