STANDARDIZATION OF PROCEDURES OF Plasmodium falciparum ANTIGEN PREPARATION FOR SEROLOGIC TESTS

Abstract

The objective of the present study is to standardize the technical variables for preparation and storage of Plasmodium falciparum and of antigen components extracted with the amphoteric detergent Zwittergent. P. falciparum obtained from in vitro culture was stored at different temperatures and for different periods of time. For each variable, antigen components of the parasite were extracted in the presence or absence of protease inhibitors and submitted or not to later dialysis. Products were stored for 15, 30 and 60 days at different temperatures and immunological activity of each extract was determined by SDS-PAGE and ELISA using positive or negative standard sera for the presence of IgG directed to blood stage antigens of P. falciparum. Antigen extracts obtained from parasites stored at -20 degrees C up to 10 days or at -70 degrees C for 2 months presented the best results, showing well-defined bands on SDS-PAGE and Western blots and presenting absorbance values in ELISA that permitted safe differentiation between positive and negative sera.

Parasite Specific Antibody Increase Induced by an Episode of Acute P. falciparum Uncomplicated Malaria

“…But these results also suggest possible differences in immunogenicity of the peptide epitopes as has been previously observed by others [ 39 ]. It is likely that immunoassays using extracts of total parasite lysate may find higher sero-prevalence’s in all residents of comparable endemic study areas since such whole-cell antigen extracts contain thousands of parasite antigens [ 40 – 42 ]. Nevertheless, the finding that all study subjects showed IgG sero-reactivity to at least one of the tested three peptides by day 42 ( Fig 1 ) suggests that antibody priming by blood-stage targeted vaccines such as GMZ2 could be boosted by the few infections experienced annually in moderate-transmission endemic regions.…”

Immune responses to multiple antigen peptides containing T and B epitopes from Plasmodium falciparum circumsporozoite protein of Brazilian individuals naturally exposed to malaria

“…Sera were also assayed for detection of anti‐ P. falciparum blood stage IgG antibodies as described previously by Avila et al . (12).…”

“…Results were considered positive for values greater than the mean RI of 100 sera samples from unexposed blood donors, assayed against each antigen. Sera were also assayed for detection of anti-P. falciparum blood stage IgG antibodies as described previously by Avila et al (12).…”

Validação de teste ELISA para pesquisa de anticorpos anti-MSP119 de Plasmodium vivax visando à aplicação em serviços hemoterápicos do Brasil em áreas não endêmicas para malária

“…Em áreas não endêmicas, suas principais indicações estão na triagem de doadores em bancos de sangue, na elucidação de casos clínicos indefinidos, na malária críptica e na detecção de assintomáticos (Warhurst e Williams, 1996). (Sanchez et al, 1993;Ávila et al, 1998;Coelho et al, 2007), antígenos recombinantes (Medeiros et al, 2013;Riccio et al, 2013;Coelho et al, 2007) e peptídeos sintéticos de proteínas específicas do estágio eritrocítico (Graves et al, 1992;Nebie et al, 2009).…”