Malaria serology: performance of six Plasmodium falciparum antigen extracts and of three ways of determining serum titers in IgG and IgM-ELISA Sorologia da malária: desempenho de seis diferentes extratos antigênicos de Plasmodium falciparum e de três métodos de determinação de títulos de soros no teste ELISA-IgG e IgM

• Published in: Revista do Instituto de Medicina Tropical de São Paulo
• Main Authors: Maria Carmen Arroyo Sanchez, Sandra do Lago Moraes de Avila, Vera de Paula Quartier-Oliveira, Antonio Walter Ferreira
• Format: Article in Journal/Newspaper
• Language: English
• Published: Universidade de São Paulo (USP) 1993
• Subjects: Malaria; Serology; ELISA; Plasmodium falciparum; Antigen extracts; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1590/S0036-46651993000600004; https://doaj.org/article/4b6feb2ee9c54e0b811c5f40a94831b1

The study evaluated six Plasmodium falciparum antigen extracts to be used in the IgG and IgM enzyme-linked immunosorbent assays (ELISA), for malaria diagnosis and epidemiological studies. Results obtained with eighteen positive and nine negative control sera indicated that there were statistically significant differences among these antigen extracts (Multifactor ANOVA, p< 0.0001). Urea, sodium deoxycholate and Zwittergent antigen extracts performed better than did the three others, their features being very similar for the detection of IgG antibodies. Urea, alkaline and sodium deoxycholate antigen extracts proved to be better than the others for the detection of IgM antibodies. A straight line relationship was found between the optical densities (or their respective log 10) and the log 10 of antibody dilutions, with a very constant slope. Thus serum titers could be determined by direct titration and by two different equations, needing only one serum dilution. For IgM antibody detections, log 10 expression gave results that better correlated with direct titration (95% Bonferroni). For IgG antibody detections, the titer differences were not significant. The reproducibility of antibody titers and antigen batches was also evaluated, giving satisfactory results. Este estudo avaliou seis extratos antigênicos de Plasmodium falciparum para utilização no diagnóstico da malária e em estudos epidemiológicos, empregando o teste "enzyme-linked immunosorbent assay" (ELISA) para a pesquisa de anticorpos das classes IgG e IgM. Os resultados obtidos empregando dezoito soros padrão positivo e nove padrão negativo, indicaram que houve diferenças estatisticamente significativas entre os extratos antigênicos estudados (Multifactor ANOVA, p <0,0001). Extratos antigênicos preparados com uréia, desoxicolato de sódio e Zwittergent forneceram melhores resultados que os demais e se comportaram de modo bastante semelhante, para a detecção de anticorpos IgG. Extratos antigenicos de uréia, alcalino e de desoxicolato de sódio foram os ...