| 1. |
- Fasanya, Adebimpe, et al.
(author)
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Anti-phosphatidylserine antibody levels are low in multigravid pregnant women in a malaria-endemic area in Nigeria, and do not correlate with anti-VAR2CSA antibodies
- 2023
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In: Frontiers in cellular and infection microbiology. - : Frontiers Media SA. - 2235-2988. ; 13
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Journal article (peer-reviewed)abstract
- Anemia is a common malaria-associated complication in pregnant women in endemic regions. Phosphatidylserine (PS) is exposed to the immune system during the massive destruction of red blood cells (RBCs) that accompany malaria, and antibodies against PS have been linked to anemia through destruction of uninfected RBCs. We determined levels of anti-PS IgG antibodies in pregnant women in Ibadan, Nigeria and correlated them to parameters of importance in development of anemia and immunity. Anti-PS correlated inversely with Packed Cell Volume (PCV), indicating that the antibodies could contribute to anemia. There was no correlation with anti-VAR2CSA IgG, haptoglobin or parasitemia, indicating that the modulation of anti-PS response is multifactorial in nature. Anti-PS levels were lowest in multigravidae compared to both primigravidae and secundigravidae and correlated inversely with age. In conclusion, lower levels of anti-PS in multigravidae could be beneficial in avoiding anemia.
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| 2. |
- Lugaajju, Allan, et al.
(author)
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Flow Cytometry Assay of Plasmodium Falciparum-Specific B-Cell Proportions
- 2022
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In: Methods in Molecular Biology. - New York, NY : Springer US. - 1940-6029 .- 1064-3745. - 9781071621899 ; 2470, s. 681-688
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Book chapter (peer-reviewed)abstract
- Detection of P. falciparum-specific subpopulations of B-cells is important for studies of immunity in malaria. This protocol relies on the photostability and protein loading capacity of carboxylated quantum dots to detect a broad range of different P. falciparum-specific B-cells. Infected red blood cell ghosts, obtained by permeabilization of infected cells with Streptolysin O, are coupled with carboxyl quantum dots using N-ethyl-N-dimethylaminopropyl-carbodiimide condensation. Immunophenotyping of P. falciparum-specific B-cells is performed by flow cytometry using Fc-receptor block, quantum dot-infected red blood cell ghost conjugates, and fluorochrome-conjugated anti-human CD19 mouse monoclonal antibodies.
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| 3. |
- Mortazavi, Susanne E., et al.
(author)
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Acquisition of complement fixing antibodies targeting Plasmodium falciparum merozoites in infants and their mothers in Uganda
- 2023
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In: Frontiers in Immunology. - 1664-3224. ; 14
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Journal article (peer-reviewed)abstract
- Background: Antibody-mediated complement fixation has previously been associated with protection against malaria in naturally acquired immunity. However, the process of early-life development of complement-fixing antibodies in infants, both in comparison to their respective mothers and to other immune parameters, remains less clear. Results: We measured complement-fixing antibodies in newborns and their mothers in a malaria endemic area over 5 years follow-up and found that infants’ complement-fixing antibody levels were highest at birth, decreased until six months, then increased progressively until they were similar to birth at five years. Infants with high levels at birth experienced a faster decay of complement-fixing antibodies but showed similar levels to the low response group of newborns thereafter. No difference was observed in antibody levels between infant cord blood and mothers at delivery. The same result was found when categorized into high and low response groups, indicating placental transfer of antibodies. Complement-fixing antibodies were positively correlated with total schizont-specific IgG and IgM levels in mothers and infants at several time points. At nine months, complement-fixing antibodies were negatively correlated with total B cell frequency and osteopontin concentrations in the infants, while positively correlated with atypical memory B cells and P. falciparum-positive atypical memory B cells. Conclusion: This study indicates that complement-fixing antibodies against P. falciparum merozoites are produced in the mothers and placentally-transferred, and they are acquired in infants over time during the first years of life. Understanding early life immune responses is crucial for developing a functional, long lasting malaria vaccine.
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| 4. |
- Mortazavi, Susanne E., et al.
(author)
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Osteopontin and malaria : no direct effect on parasite growth, but correlation with P. falciparum-specific B cells and BAFF in a malaria endemic area
- 2021
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In: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 21:1
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Journal article (peer-reviewed)abstract
- Background: The dysregulation of B cell activation is prevalent during naturally acquired immunity against malaria. Osteopontin (OPN), a protein produced by various cells including B cells, is a phosphorylated glycoprotein that participates in immune regulation and has been suggested to be involved in the immune response against malaria. Here we studied the longitudinal concentrations of OPN in infants and their mothers living in Uganda, and how OPN concentrations correlated with B cell subsets specific for P. falciparum and B cell activating factor (BAFF). We also investigated the direct effect of OPN on P. falciparum in vitro. Results: The OPN concentration was higher in the infants compared to the mothers, and OPN concentration in infants decreased from birth until 9 months. OPN concentration in infants during 9 months were independent of OPN concentrations in corresponding mothers. OPN concentrations in infants were inversely correlated with total atypical memory B cells (MBCs) as well as P. falciparum-specific atypical MBCs. There was a positive correlation between OPN and BAFF concentrations in both mothers and infants. When OPN was added to P. falciparum cultured in vitro, parasitemia was unaffected regardless of OPN concentration. Conclusions: The concentrations of OPN in infants were higher and independent of the OPN concentrations in corresponding mothers. In vitro, OPN does not have a direct effect on P. falciparum growth. Our correlation analysis results suggest that OPN could have a role in the B cell immune response and acquisition of natural immunity against malaria.
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| 5. |
- Tijani, Muyideen Kolapo, et al.
(author)
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How to Detect Antibodies Against Babesia divergens in Human Blood Samples
- 2024
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In: Open Forum Infectious Diseases. - : OXFORD UNIV PRESS INC. - 2328-8957. ; 11:2
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Journal article (peer-reviewed)abstract
- Background. Today only indirect fluorescent antibody assays (IFAs) are commercially available to detect antibodies against Babesia divergens in humans. IFA is subjective and requires highly experienced staff. We have therefore developed an enzyme-linked immunosorbent assay (ELISA)-based method for measuring anti-B. divergens immunoglobulin G antibodies in human blood samples. Methods. Crude merozoite extract from in vitro cultures of a new B. divergens isolate was used in ELISA to detect antibodies in different sets of samples: Borrelia burgdorferi-positive samples, healthy individuals, tick-bitten individuals including follow-up samples 3 months later, positive control samples from patients with an active Babesia infection, and samples from malaria-endemic regions. As a reference, IFA was used to detect antibodies in the tick-bitten samples. Western blot was used to evaluate reactions against specific bands in extracts with/without parasites. Results. Using IFA as the reference method, the sensitivity and specificity of the ELISA were 86% (12/14) and 100% (52/52). There was a very high correlation (r = -0.84; P = .0004) between IFA dilution factors and ELISA absorbances among the samples classified as positive. Five percent of the B. burgdorferi-positive samples were judged as weakly positive and 5% as strongly positive in our ELISA. Western blot showed that the immunodominant antigens (∼120 kDa) were from merozoites and not from erythrocytes. Conclusions. This ELISA can detect antibodies directed against B. divergens, and it can be a useful and easy assay to handle compared with IFA. The ELISA can also measure high and low levels of antibodies, which could give insight into the recency of a B. divergens infection.
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| 6. |
- Tijani, Muyideen Kolapo, et al.
(author)
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Naturally acquired antibodies against Plasmodium falciparum : Friend or foe?
- 2021
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In: Pathogens. - : MDPI AG. - 2076-0817. ; 10:7
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Research review (peer-reviewed)abstract
- Antibodies are central to acquired immunity against malaria. Plasmodium falciparum elicits antibody responses against many of its protein components, but there is also formation of antibodies against different parts of the red blood cells, in which the parasites spend most of their time. In the absence of a decisive intervention such as a vaccine, people living in malaria endemic regions largely depend on naturally acquired antibodies for protection. However, these antibodies do not confer sterile immunity and the mechanisms of action are still unclear. Most studies have focused on the inhibitory effect of antibodies, but here, we review both the beneficial as well as the potentially harmful roles of naturally acquired antibodies, as well as autoantibodies formed in malaria. We discuss different studies that have sought to understand acquired antibody responses against P. falciparum antigens, and potential problems when different antibodies are combined, such as in naturally acquired immunity.
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