Measuring antibody avidity to Plasmodium falciparum merozoite antigens using a multiplex immunoassay approach
Autor: | Alex Kayatani, Winifrida Kidima, Rose F. G. Leke, Diane Wallace Taylor, Naveen Bobbili, Samuel Tassi Yunga |
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Rok vydání: | 2020 |
Předmět: |
Adult
Male lcsh:Arctic medicine. Tropical medicine Adolescent lcsh:RC955-962 Plasmodium falciparum Antibody Affinity Multiplex immunoassay Antibodies Protozoan Antigens Protozoan Enzyme-Linked Immunosorbent Assay Antibodies lcsh:Infectious and parasitic diseases Affinity maturation Young Adult Antigen parasitic diseases medicine Humans lcsh:RC109-216 Avidity Multiplex Malaria Falciparum Immunoassay biology medicine.diagnostic_test Merozoites Chemistry Research Antibody avidity Infant Middle Aged biology.organism_classification Virology Malaria Chaotropic agent Infectious Diseases biology.protein Female Parasitology Methods study Antibody |
Zdroj: | Malaria Journal, Vol 19, Iss 1, Pp 1-12 (2020) Malaria Journal |
ISSN: | 1475-2875 |
DOI: | 10.1186/s12936-020-03243-3 |
Popis: | Background Antibodies (Ab) play a significant role in immunity to Plasmodium falciparum malaria. Usually, following repeated exposure to pathogens, affinity maturation and clonal selection take place, resulting in increased antibody avidity. However, some studies suggest affinity maturation may not occur to malaria antigens in endemic areas. Information on development of antibody avidity is confusing and conflicting, in part, because different techniques have been used to measure avidity. Today, bead-based multiplex immunoassays (MIA) are routinely used to simultaneously quantitate antibody levels to multiple antigens. This study evaluated the feasibility of developing an avidity MIA with 5 merozoite antigens (AMA1, EBA-175, MSP1-42, MSP2, MSP3) that uses a single chaotropic concentration. Methods The most common ELISA protocols that used the chaotropic reagents guanidine HCl (GdHCl), urea, and ammonium thiocyanate (NH4SCN) were adapted to a multiplex MIA format. Then, different concentrations of chaotropes and incubation times were compared and results were expressed as an Avidity Index (AI), i.e., percentage of antibody remaining bound in the presence of chaotrope. Experiments were conducted to (i) identify the assay with the widest range of AI (discriminatory power), (ii) determine the amount of chaotrope needed to release 50% of bound Ab using plasma from adults and infants, and (iii) evaluate assay repeatability. Results Overall, 4 M GdHCl and 8 M urea were weaker chaotropes than 3 M NH4SCN. For example, they failed to release significant amounts of Ab bound to MSP1-42 in adult plasma samples; whereas, a range of AI values was obtained with NH4SCN. Titration of NH4SCN revealed that 2 M NH4SCN gave the widest range of AI for the 5 antigens. Binding studies using plasma from 40 adults and 57 1-year old infants in Cameroon showed that 2.1 M ± 0.32 (mean ± SD) NH4SCN (adults) and 1.8 M ± 0.23 M (infants) released 50% of bound Ab from the merozoite antigens. Conclusions An avidity MIA is feasible for the 5 merozoite antigens that uses a single concentration (2 M) of NH4SCN. The assay provides a simple method to quickly obtain information about Ab quantity and quality in the acquisition of immunity to malaria in endemic populations. |
Databáze: | OpenAIRE |
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