Malaria serology: performance of six Plasmodium falciparum antigen extracts and of three ways of determining serum titers in IgG and IgM-ELISA

Abstract

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 log10) and the log10 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, log10 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.

Malaria in pregnant women living in areas of low transmission on the southeast Brazilian Coast: molecular diagnosis and humoural immunity profile

“…ELISA - An adapted protocol described elsewhere was applied for the detection of IgG antibodies against P. falciparum and P. vivax . Crude P. falciparum antigen was extracted with Zwittergent ® (Calbiochem ® , Germany) and employed at 0.5 µg/mL for the detection of IgG antibodies against all Plasmodium species through cross-reactions ( Sanchez et al 1993 , Coelho et al 2007 ). To detect P. vivax antibodies, the recombinant antigen His 6 Pv MSP1 19 was used at 4 µg/mL ( Coelho et al 2007 ).…”

Asymptomatic infection in individuals from the municipality of Barcelos (Brazilian Amazon) is not associated with the anti-Plasmodium falciparum glycosylphosphatidylinositol antibody response

“…To further characterise the previous exposure of the studied individuals to Plasmodium , we also evaluated the Ab response to a crude P. falciparum extract by ELISA {obtained according to Sanchez et al (1993)} as well as to the recombinant merozoite surface proteins (MSP) of P. falciparum ( Pf MSP3) (a kind gift from Pierre Druilhe from Vac-4-All) and P. vivax ( Pv MSP1- 19 ) (produced by Arianni Rondelli Sanchez and Eduardo Milton Ramos-Sanchez at the Institute of Tropical Medicine, state of São Paulo, Brazil), as described elsewhere (Theisen et al 2001, Cunha et al 2001, respectively). The Ab levels to all antigens in the asymptomatic individuals were significantly related to age (crude antigen: r = 0.523, p = 0.004; Pf MSP3: r = 0.386, p = 0.04 and Pv MSP1- 19 : r = 0.496, p = 0.007, Spearman's rank correlation), indicating that, in a scenario of supposed premunition to malaria in areas of intense disease transmission (including those in the Brazilian Amazon), antiparasitic responses can be associated with age and the consequent cumulative exposure to infection.…”

Asymptomatic Plasmodium infection in a residual malaria transmission area in the Atlantic Forest region: Implications for elimination

“…Serological examinations were performed using enzymelinked immunosorbent assay (ELISA) with erythrocytic antigens for P. falciparum and P. vivax and immunofluorescence assay (IFA) for P. malariae. IgG antibodies were detected by ELISA using a crude blood stage P. falciparum antigen extracted with Zwittergent ® (Calbiochem, Billerica, MA, USA) 15 and MSP1-19 recombinant antigen of P. vivax 16 . Reactions were assessed by measuring the absorbance at 492 nm using Titertek Multiskan MCC/340 (Labsystems Diagnostics Group, Vantaa, Finland).…”