Development and evaluation of an indirect ELISA using multiepitope antigen for intestinal schistosomiasis diagnosis

This study was financed by the Programa de Apoio à Pesquisa Estratégica em Saúde (PAPES VII/FIOCRUZ). E. Oliveira was supported by CNPq-Brazil (Conselho Nacional de Desenvolvimento Científico e Tecnológico; Proc. 313471/2019-3)Federal University of Minas Gerais. Institute of Biological Sciences. Department of Parasitology. Belo Horizonte, MG, Brazil / Oswaldo Cruz Foundation. René Rachou Institute. Belo Horizonte, MG, Brazil.Oswaldo Cruz Foundation. René Rachou Institute. Belo Horizonte, MG, Brazil.Federal University of Minas Gerais. Institute of Biological Sciences. Department of Parasitology. Belo Horizonte, MG, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde e Ambiente. Instituto Evandro Chagas. Ananindeua, PA, Brasil.Oswaldo Cruz Foundation. René Rachou Institute. Belo Horizonte, MG, Brazil.Federal University of Minas Gerais. Institute of Biological Sciences. Department of Parasitology. Belo Horizonte, MG, Brazil.The laboratory diagnosis of intestinal schistosomiasis, carried out by detecting parasite eggs in feces, has low sensitivity when applied to individuals with low parasitic load. Serological tests can be more sensitive for the diagnosis of the disease. Therefore, the objective of this work was to develop and evaluate an ELISA-based immunoenzymatic assay, using a Schistosoma mansoni multiepitope antigen (ELISA IgG anti-SmME). For this, the amino acid sequences of S. mansoni cathepsin B and asparaginyl endopeptidase were submitted to the prediction of B cell epitopes and, together with peptide sequences obtained from earlier works, were used in the construction of a minigene. The multiepitope protein was expressed in Escherichia coli and the performance of the ELISA IgG anti-SmME for schistosomiasis was evaluated using serum samples from 107 individuals either egg positive or negative. In addition, 11 samples from individuals with other helminth infections were included. The ELISA IgG anti-SmME showed a sensitivity of 81.1% and a specificity of 46.1%. Further analysis revealed a 77.2% sensitivity in diagnosis of individuals with egg counts of ≤12 epg (eggs per gram feces) and 87.5% for individuals with 13–99 epg. It is worth mentioning that, to our knowledge, this was the first study using a multiepitope recombinant antigen in an ELISA for diagnosis of intestinal schistosomiasis, which demonstrated promising results in the diagnosis of individuals with low parasitic loads