Antigen Extracts Research Articles

The impact of early life exposure to Plasmodium falciparum on the development of naturally acquired immunity to malaria in young Malawian children

BackgroundAntibodies targeting malaria blood-stage antigens are important targets of naturally acquired immunity, and may act as valuable biomarkers of malaria exposure.MethodsSix-hundred and one young Malawian children from a randomized trial of prenatal nutrient supplementation with iron and folic acid or pre- and postnatal multiple micronutrients or lipid-based nutrient supplements were followed up weekly at home and febrile episodes were investigated for malaria from birth to 18 months of age. Antibodies were measured for 601 children against merozoite surface proteins (MSP1 19kD, MSP2), erythrocyte binding antigen 175 (EBA175), reticulocyte binding protein homologue 2 (Rh2A9), schizont extract and variant surface antigens expressed by Plasmodium falciparum-infected erythrocytes (IE) at 18 months of age. The antibody measurement data was related to concurrent malaria infection and to documented episodes of clinical malaria.ResultsAt 18 months of age, antibodies were significantly higher among parasitaemic than aparasitaemic children. Antibody levels against MSP1 19kD, MSP2, schizont extract, and IE variant surface antigens were significantly higher in children who had documented episodes of malaria than in children who did not. Antibody levels did not differ between children with single or multiple malaria episodes before 18 months, nor between children who had malaria before 6 months of age or between 6 and 18 months.ConclusionsAntibodies to merozoite and IE surface antigens increased following infection in early childhood, but neither age at first infection nor number of malaria episodes substantially affected antibody acquisition. These findings have implications for malaria surveillance during early childhood in the context of elimination.Trials registration Clinical Trials Registration: NCT01239693 (Date of registration: 11-10-2010). URL: http://www.ilins.org

Optimisation and comparison of different methods for antigen extraction from oil adjuvant inactivated infectious bursal disease vaccine

Antigenic quantification based in vitro method for potency estimation of oil adjuvant inactivated vaccine requires a suitable antigen exaction protocol for maximum recovery of antigen from the vaccine. To find out the suitable protocol, in the present study, seven different organic solvents including isopropyl Myristate (IPM), isopropyl Palmitate (IPP), benzyl alcohol, butanol, acetone, chloroform/methanol and dimethyl sulphoxide (DMSO) were tested to recover the antigen from the six oil adjuvant inactivated infectious bursal disease (IBD) and two Newcastle disease (NDV) vaccines from different manufacturers. The mean OD450 values of antigen extracted from all the vaccines using different organic solvents were determined by in house developed sandwich ELISA (sELISA). The mean average ODs of all six IBD vaccines were 2.794, 2.520, 2.690 and 2.359, respectively from IPM, IPP, benzyl alcohol and butanol methods. Antigen recovered by acetone, chloroform/methanol and DMSO methods gave ODs value of 0.019, 0.203 and 0.062, respectively. Based on the sELISA results, IPM and IPP methods were found as most appropriate for antigen extraction from oil adjuvant IBD vaccine. The antigen recovery was further confirmed by protein estimation of antigen recovered by IPM and IPP. The results of the present study indicated that IPM and IPP were the two appropriate organic solvents for antigen extraction from oil adjuvant IBD vaccine.

IgM and IgG Antibody Enzyme Linked Immunosorbent Assay Profile Detected Using Adult Schistosoma guineensis Extract In Sera from Cameroonian Infected by Schistosoma mansoni, Schistosoma haematobium and Schistosoma guineensis

Schistosomiasis is endemic in Cameroon with three Schistosoma species infecting human in many areas. Data from many countries endemic for S.mansoni, S.haematobium and S.japonicum reported an age-dependent antibody response profile using homologous adult schistosome antigen extract. Less is known about the antibody profile in schistosomiasis endemic areas in Cameroon. This study aimed to assess the IgM and IgG antibody profiles using adult S.guineensis extract in immune sera from Schistosoma egg positive Cameroonians from intestinal or urinary schistosomiasis endemic areas. Whole adult S.guineensis antigen was extracted from a Cameroonian S.guineensis strain maintained in laboratory. The antigen extract was a supernatant obtained after centrifugation of grinded freeze-thawed 45 days old worms in enzyme inhibitor solution. Sera were obtained from residents of schistosomiasis endemic areas with microscopically confirmed monospecific infection by S.guineensis, S.mansoni or S.haematobium and Schistosoma free control sera from non endemic area. IgM and IgG antibody titers detection was proceeded by indirect ELISA using HRP-conjugated secondary IgM or IgG antibody. Optical densities (OD) were recorded with a spectrophotometer plate reader at 495 nm and mean OD were statistically analyzed according to age using Student t-test and egg load using ANOVA test. A total of 189 sera were tested. Sera from S.haematobium, S.mansoni and S.guineensis infections represented 68, 73 and 46 respectively. Of S.mansoni infection sera, 31 were collected at Lagdo and 42 in S.mansoni monospecific focus. Age had no significant influence on mean IgM and IgG antibodies OD although mean IgM and IgG changed with age. Mean IgG antibody increased with age in the three schistosomiasis sera. According to age, mean IgM decreased in S.guineensis infections sera, decreased from young to participants aged 15 to 24 years then increased in older in schistosomiasis mansoni sera. In schistosomiasis haematobium sera, mean IgM increased from young to participants aged 15 to 24 years then decreased in older. Egg load influenced significantly mean IgM and IgG titers. Mean IgM OD decreased with egg load in each of the schistosomiasis whereas mean IgG decreased in intestinal schistosomiasis sera. Mean IgM and IgG antibody titers detected with adult S.guineensis extract using ELISA technique in either intestinal or urinary schistosomiasis endemic areas in Cameroon were not age dependent but egg load depended on egg load in urine and stool samples. Diagnostic performance of the adult S.guineensis extract in antibody detection has been tested.

Study of Humeral Immune Response and Some of the Blood Variables in Mice Balb/c Treated with LPS of Klebsiella pneumoniae Antigen and Glycyrrhiza glabra Extract

In this work, lipopolysaccharides of Klebsiella pneumonia and extract of Glycyrrhiza glabra were used to investigate the humoral immunity in mice Balb/c (in vivo). In contrast, little is known about humeral immunity induced by LPS and Glycyrrhiza glabra. Some parameters were used to achieve this study, are WBC and differential count, Concentration of antibodies IgA, IgM, IgG and Concentration of complement proteins type C3 and C4/mg/100. The results showed there are a significant change in a parameters values in IgA, IgM, IgG and Concentration of complement proteins type C3 and C4, also in CBC and differentiated WBC.

Active Tuning of Synaptic Patterns Enhances Immune Discrimination.

Immune cells learn about their antigenic targets using tactile sense: a self-organized motif named immunological synapse forms between an immune cell and an antigen-presenting cell (APC) during recognition. Via synapses, immune cells apply mechanical pulling forces to selectively extract antigen (Ag) from APCs. Curiously, depending on its stage of development, a B lymphocyte exhibits distinct synaptic patterns and uses force at different strength and timing, which appears to strongly impact its ability to distinguish Ag affinities. We use a statistical-mechanical model to study how the experimentally observed synaptic architectures can originate from normal cytoskeletal forces coupled to the lateral organization of mobile receptors, and show how this active regulation scheme, collective in nature, may enhance the efficiency and capacity of discrimination.

Galectin-8 Favors the Presentation of Surface-Tethered Antigens by Stabilizing the B Cell Immune Synapse

SummaryComplete activation of B cells relies on their capacity to extract tethered antigens from immune synapses by either exerting mechanical forces or promoting their proteolytic degradation through lysosome secretion. Whether antigen extraction can also be tuned by local cues originating from the lymphoid microenvironment has not been investigated. We here show that the expression of Galectin-8—a glycan-binding protein found in the extracellular milieu, which regulates interactions between cells and matrix proteins—is increased within lymph nodes under inflammatory conditions where it enhances B cell arrest phases upon antigen recognition in vivo and promotes synapse formation during BCR recognition of immobilized antigens. Galectin-8 triggers a faster recruitment and secretion of lysosomes toward the B cell-antigen contact site, resulting in efficient extraction of immobilized antigens through a proteolytic mechanism. Thus, extracellular cues can determine how B cells sense and extract tethered antigens and thereby tune B cell responses in vivo.

IgG Induced by Vaccination With Ascaris suum Extracts Is Protective Against Infection.

Human ascariasis has a global and cosmopolitan distribution, and has been characterized as the most prevalent neglected tropical disease worldwide. The development of a preventive vaccine is highly desirable to complement current measures required for this parasitic infection control and to reduce chronic childhood morbidities. In the present study, we describe the mechanism of protection elicited by a preventive vaccine against ascariasis. Vaccine efficacy was evaluated after immunization with three different Ascaris suum antigen extracts formulated with monophosphoryl lipid A (MPLA) as an adjuvant: crude extract of adult worm (ExAD); crude extract of adult worm cuticle (CUT); and crude extract of infective larvae (L3) (ExL3). Immunogenicity elicited by immunization was assessed by measuring antibody responses, cytokine production, and influx of tissue inflammatory cells. Vaccine efficacy was evaluated by measuring the reductions in the numbers of larvae in the lungs of immunized BALB/c mice that were challenged with A. suum eggs. Moreover, lung physiology and functionality were tested by spirometry to determine clinical efficacy. Finally, the role of host antibody mediated protection was determined by passive transfer of serum from immunized mice. Significant reductions in the total number of migrating larvae were observed in mice immunized with ExL3 61% (p < 0.001), CUT 59% (p < 0.001), and ExAD 51% (p < 0.01) antigens in comparison with non-immunized mice. For the Ascaris antigen-specific IgG antibody levels, a significant and progressive increase was observed with each round of immunization, in association with a marked increase of IgG1 and IgG3 subclasses. Moreover, a significant increase in concentration of IL-5 and IL-10 (pre-challenge) in the blood and IL-10 in the lung tissue (post-challenge) was induced by CUT immunization. Finally, ExL3 and CUT-immunized mice showed a marked improvement in lung pathology and tissue fibrosis as well as reduced pulmonary dysfunction induced by Ascaris challenge, when compared to non-immunized mice. Moreover, the passive transfer of specific IgG antibodies from ExL3, CUT, and ExAD elicited a protective response in naïve mice, with significant reductions in parasite burdens in lungs of 65, 64, and 64%, respectively. Taken together, these studies indicated that IgG antibodies contribute to protective immunity.

The Art and Science of Diagnosing Mycoplasma pneumoniae Infection.

Mycoplasma pneumoniae causes a significant burden of disease in children as both upper and lower respiratory tract infections (URTIs and LRTIs). A positive pharyngeal polymerase chain reaction (PCR) or serology for M. pneumoniae can be found in 4–39% of children hospitalized with community-acquired

Towards a subunit vaccine from a Shigella flexneri ΔtolR mutant

Disruption of one or more components of the Tol-Pal system, involved in maintaining the integrity of the outer membrane of Gram-negative bacteria, has been proposed as a method to increase the yield obtained from natural production of outer membrane vesicles (OMV). We present a new OMV-based product, obtained from genetically modified Shigella flexneri 2a with a non-polar deletion in tolR and heat-inactivated (HT-ΔtolR). The S. flexneri ΔtolR strain lead to a higher release of vesicles, more than 8-times when compared to the yield obtained from chemically inactivated wild type strain. S. flexneri mutant strain appeared to be more sensitive to different chemical compounds, including antibiotics, bile salts or human complement and it was also less virulent in both in vitro and in vivo assays. The mutation produced some changes in the LPS O-chain and protein expression. S. flexneri ΔtolR was enriched in long and very long LPS O-chain and expressed a different pattern of surface proteins or lipoproteins. In vitro toxicity and activation properties were determined in Raw 267.4 macrophage cell line. HT-ΔtolR antigenic complex was non-cytotoxic and activation markers, such as MHC-II or CD40, were highly expressed during incubation with this product. Finally, preliminary studies on the antibody response elicited by HT-ΔtolR demonstrated a robust and diverse response in mice. Considering these promising results, HT-ΔtolR antigenic extract appears as a new potential vaccine candidate to face shigellosis.

Assessment of in vitro potency of inactivated Newcastle disease oil-adjuvanted vaccines using hemagglutination test and blocking ELISA.

Aim:The present study was aimed to establish a protocol for the evaluation of the in vitro potency of commercial inactivated Newcastle disease virus (NDV) oil-adjuvanted vaccines using hemagglutination test (HA) and blocking ELISA (B-ELISA) based on polyclonal antibodies.Materials and Methods:Aqueous phases from a total of 47 batches of inactivated NDV vaccines manufactured by 20 different companies were extracted with isopropyl myristate. The viral antigen in each sample was detected and quantified by a standard HA test and a B-ELISA assay. To verify the efficiency of the antigen extraction method used in the batches which showed HA and to test the validity of using in vitro antigen quantification by HA and B-ELISA tests, a subset of 13 batches (selected from the total 47 batches) was inoculated in groups of 3-4-week-old specific pathogen-free chickens using the recommended vaccine dose. The immunogenicity of the selected vaccine batches was assessed by the NDV-hemagglutination inhibition antibody titers in individual serum samples collected 4 weeks after vaccination. Further, the efficacy of the vaccines and their protection rates were determined by a challenge test carried out for the vaccinated chickens with the Egyptian 2012 isolate of the virulent NDV genotype VII.Results:A strong correlation was observed between HA titers and B-ELISA mean titers in the tested 47 batches (R2=0.817). This indicated the possibility of using the latter in vitro assays for vaccine potency assessment. The recommended protective NDV antigen titer measured by B-ELISA was determined to be 28 ELISA units per dose. The comparison between the HA titers of the aqueous extracts of test vaccines and the corresponding results of in vivo potency assays (i.e., immunogenicity and efficacy), including antibody titers in the serum of vaccinated birds, indicated that the efficiency of the antigen extraction used may interfere with obtaining a strong correlation between the in vitro and in vivo results.Conclusion:HA or B-ELISA tests can be used as rapid and cost-effective alternatives to traditional in vivo potency tests for vaccine potency assessment by quantifying the NDV antigen present in aqueous phase extracts of the tested vaccines. The latter in vitro protocol, however, requires efficient extraction of the antigen to be able to obtain good correlation with the traditional in vivo potency tests.

Evaluation of Decellularized Bovine Tendon Sheets for Achilles Tendon Defect Reconstruction in a Rabbit Model

Background: Achilles tendon (AT) defects frequently occur in trauma and chronic injuries. Currently, no method can satisfactorily reconstruct the AT with completely restored function. Purpose: To evaluate the postoperative outcomes of AT defect reconstruction with decellularized bovine tendon sheets (DBTSs) in a rabbit model. Study Design: Controlled laboratory study. Methods: DBTSs were prepared from bovine tendons after compression, decellularization, antigen extraction, freeze drying, and sterilization. Platelet-rich plasma (PRP) was obtained by differential centrifugation. Sixty-three rabbits were used in this study, and the AT defect model was created bilaterally. All rabbits were divided into 3 groups (n = 21). In the DBTS group and the DBTS + PRP group, 2-cm-long AT was excised and reconstructed by DBTSs or PRP-treated DBTSs. In the control group, the rabbits underwent AT transection, and stumps were sutured. After surgery, all rabbits were assessed by ultrasonography and magnetic resonance imaging and then sacrificed for histological examination and biomechanical testing at 4, 8, or 12 weeks. Results: Gross observations demonstrated the absence of immunologic incompatibility and rejection. Histological examination showed that DBTSs promoted host cell infiltration and new fibrous tissue integration as compared with the control group. In each group, there was an AT-like structure formation and aligned collagen fiber deposition at 12 weeks. Mechanical properties of the reconstructed AT were not significantly different among the 3 groups at 4, 8, and 12 weeks after surgery (P > .05). Ultrasonography and magnetic resonance imaging results illustrated that the reconstructed AT from each group maintained remodeling, and there was no significant difference in the echogenicity scoring (P > .05) and percentages of good and excellent (P > .05) among the 3 groups. Conclusion: DBTSs, which retain the native tendon structure and bioactive factors, had the ability to remodel and integrate into the rabbit AT and improve the healing process. Clinical Relevance: DBTSs could serve as an effective bioscaffold to reconstruct AT defects.

Mechanics of antigen extraction in the B cell synapse

B cell encounter with antigen displayed on antigen-presenting cells leads to B cell immune synapse formation, internalisation of the antigen, and stimulation of antibody responses. The sensitivity with which B cells detect antigen, and the quality and quantity of antigen that B cells acquire, depend upon mechanical properties of the immune synapse including interfacial tension, the strength of intermolecular bonds, and the compliance of the molecules and membranes that participate in antigen presentation. In this review, we discuss our current understanding of how these various physical parameters influence B cell antigen extraction in the immune synapse and how a more comprehensive understanding of B cell mechanics may promote the development of new approaches to stimulate the production of desired antibodies.

Tuning B cell responses to antigens by cell polarity and membrane trafficking

The capacity of B lymphocytes to produce specific antibodies, particularly broadly neutralizing antibodies that provide immunity to viral pathogens has positioned them as valuable therapeutic targets for immunomodulation. To become competent as antibody secreting cells, B cells undergo a series of activation steps, which are triggered by the recognition of antigens frequently displayed on the surface of other presenting cells. Such antigens elicit the formation of an immune synapse (IS), where local cytoskeleton rearrangements coupled to mechanical forces and membrane trafficking orchestrate the extraction and processing of antigens in B cells. In this review, we discuss the molecular mechanisms that regulate polarized membrane trafficking and mechanical properties of the immune synapse, as well as the potential extracellular cues from the environment, which may impact the ability of B cells to sense and acquire antigens at the immune synapse. An integrated view of the diverse cellular mechanisms that shape the immune synapse will provide a better understanding on how B cells are efficiently activated.

A conserved Leishmania hypothetical protein evaluated for the serodiagnosis of canine and human visceral and tegumentary leishmaniasis, as well as a serological marker for the posttreatment patient follow-up

In the present study, a conserved Leishmania hypothetical protein, LiHyE, was evaluated for the serodiagnosis of leishmaniasis. Results showed that it presented high sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) to serologically identify visceral leishmaniasis (VL) dogs when 40 positive sera and 95 cross-reactive samples were used. rLiHyE also showed the best results of sensitivity, specificity, PPV, and NPV to identify tegumentary leishmaniasis (TL) and VL patients when 45 leishmaniasis patients' sera and 90 cross-reactive samples were used. Results were better in comparison to those obtained when rA2 or Leishmania antigenic extract was employed as controls. The posttreatment follow-up showed that rLiHyE-specific antibodies declined significantly after the end of treatments, and a predominance of the IgG2 subclass was found in comparison to IgG1 levels in both TL and VL patients. In conclusion, rLiHyE can be considered a candidate for the serodiagnosis of canine and human leishmaniasis.

Myosin IIa Promotes Antibody Responses by Regulating B Cell Activation, Acquisition of Antigen, and Proliferation

SummaryB cell responses are regulated by antigen acquisition, processing, and presentation to helper T cells. These functions are thought to depend on contractile activity of non-muscle myosin IIa. Here, we show that B cell-specific deletion of the myosin IIa heavy chain reduced the numbers of bone marrow B cell precursors and splenic marginal zone, peritoneal B1b, and germinal center B cells. In addition, myosin IIa-deficient follicular B cells acquired an activated phenotype and were less efficient in chemokinesis and extraction of membrane-presented antigens. Moreover, myosin IIa was indispensable for cytokinesis. Consequently, mice with myosin IIa-deficient B cells harbored reduced serum immunoglobulin levels and did not mount robust antibody responses when immunized. Altogether, these data indicate that myosin IIa is a negative regulator of B cell activation but a positive regulator of antigen acquisition from antigen-presenting cells and that myosin IIa is essential for B cell development, proliferation, and antibody responses.

Bioengineered organoid models of human germinal centers

Abstract B cells undergo affinity maturation to T cell-dependent antigens within specialized microenvironments in secondary lymphoid organs termed germinal centers (GCs) resulting in the selective proliferation and differentiation of high-affinity B cells. Selection is driven by the ability of antigen-specific GC B cells to extract antigen presented on follicular dendritic cells and subsequently recruit stimuli from T follicular helper cells. Successful GC B cells ultimately differentiate into plasma cells that secrete large amounts of antigen-specific antibody, or memory B cells that contribute to long-term immunity. However, the factors that influence selection and differentiation of GC B cells in humans are not yet well understood. One challenge arises from the rapid loss of viability of human primary GC B cells ex vivo under conventional cell culture conditions. To overcome this, we bioengineered organoids using a customizable matrix along with modified feeder cell lines. When encapsulated in these organoids, primary human GC B cells exhibit enhanced viability similar to that of B cells in GCs in vivo. The low auto-fluorescent properties of these organoids allow for imaging of cellular interactions and migration. Furthermore, the customizable chemistry of the organoid matrix allows us to screen for factors that influence the differentiation and fate of human GC B cells. Improving our understanding of these processes may provide important insights in areas such as therapeutics and vaccine development.

Human germinal center B cells are intrinsically able to discriminate antigen affinity and with T cell help express plasma cell transcription factors

Abstract The selection of GC B cells that express high affinity B cell receptors (BCRs) is driven by the ability of B cells to both signal through the BCR and to extract antigen and present it to follicular helper T cells (T FH cells). Using anti-kappa antibodies of low (KD=3.9×10 −7 ) versus high (KD=2.4×10 −9 ) affinities attached to membranes as surrogate antigens, we show that LZ GC B cells are able to discriminate between these and responded only to the high affinity antigen. In contrast, naïve B cells responded to both high and low affinity antigens. LZ GC B cells engaged membrane associated surrogate antigens through highly dynamic F-actin and ezrin-rich pod-like structures that concentrated BCRs at their contact points. Using DNA-based mechanical force nano-sensors we observed robust pulling forces localized to the contact sites of the pods with the membrane. In contrast, naïve B cells formed flat stable contacts with the membranes and showed only defuse weak pulling forces. GC B cells optimally express transcription factors that drive plasma cell differentiation, namely IRF-4 and PRDM-1, in response to antigen in combination with T FH help while naïve B cells increased IRF-4 and PRDM-1 transcription in response to T FH alone and less so to antigen alone. Thus, LZ GC B cells appear to be intrinsically capable of antigen affinity discrimination and with the acquisition of T FH help BCR-activated LZ GC B cells differentiate into plasma cells.

Extraction, isolation, and concentration of calprotectin antigen (S100A8/S100A9) from granulocytes.

BackgroundCalprotectin is a promising biomarker for granulocyte activation. It is mainly measured in faeces as a marker for inflammatory bowel disease. A limitation is that there is no widely accepted calibrator.AimTo establish a method for purification of calprotectin from human granulocytes that is easily reproducible, reliable, and could contribute to a better agreement between different calprotectin methods.Methods and resultsCalprotectin was purified from granulocyte extracts using ion‐exchange chromatography. The granulocytes were separated from blood bags. The purity was analysed by analysing pixel density of a picture of the sodium dodecyl sulfate polyacrylamide gel electrophoresis and by size exclusion chromatography. The calprotectin concentration of the pure antigen solution was determined using Biuret method. The purity was >95% for 3 preparations, and their concentrations were 1079, 1080, and 1813 mg/L.ConclusionIt is possible to reproducibly prepare highly purified calprotectin antigen from human granulocytes. The preparations can be used for preparing calibrators, controls for immunological calprotectin assays, and immunisation for raising antibodies against human calprotectin in hens.

Identification and Preliminary Evaluation of a Novel Recombinant Protein for Serodiagnosis of Strongyloidiasis.

Strongyloides stercoralis is a human parasite that can cause a long-term infection. In immunosuppressed patients, strongyloidiasis may be fatal when there is overwhelming autoinfection resulting in the migration of large numbers of larvae through many organs. Definitive diagnosis is still a challenge, and a combination of symptoms, microscopic identification, and serology test results are often used to arrive at a clinical decision. However, intermittent larval excretion, low parasite burden, and occult infections are challenges with parasitological diagnosis of infection with S. stercoralis. Meanwhile, serologic tests using immunoglobulin G and parasite antigen extract have problems of cross-reactivity with other helminthic infections. Recombinant antigen-based serodiagnosis is a good alternative to overcome the laboratory diagnostic issues. Herein, we report on the isolation of cDNA clone encoding an antigen of potential diagnostic value identified from immunoscreening of a S. stercoralis cDNA library. The translated protein had highest similarity to Strongyloides ratti immunoglobulin-binding protein 1. The recombinant antigen produced, rSs1a, was assessed using western blot and enzyme-linked immunosorbent assay. The latter showed 96% diagnostic sensitivity and 93% specificity; thus, rSs1a has good potential for use in serodiagnosis of human strongyloidiasis.

Effect of nutrient supplementation on the acquisition of humoral immunity to Plasmodium falciparum in young Malawian children

BackgroundThere is evidence that suggests that undernutrition has a detrimental effect on malarial immunity in children. The aim of the study was to discover whether nutrient supplementation improved development of malarial antibody immunity in children up to 18 months of age.MethodsThe study was conducted with a subset of 432 Malawian children from a randomized controlled trial of nutritional supplements. The arms included pre- and postnatal small-quantity lipid-based nutrient supplements for both mother and child; prenatal supplementation with iron and folic acid; and pre- and postnatal supplementation with multiple micronutrients. Paired plasma samples were collected at 6 and 18 months of age. The levels of antibodies against merozoite surface protein 1 (MSP1 19kD) and MSP2, erythrocyte binding antigen 175 (EBA175), reticulocyte binding protein homologue 2A (Rh2A9), schizont extract and variant antigens expressed on the surface of infected erythrocytes were measured.ResultsAt 18 months of age, 5.4% of children were parasitaemic by microscopy and 49.1% were anaemic. Antibodies to the tested merozoite antigens and schizont extract increased between 6 and 18 months and this increase was statistically significant for MSP1, MSP2 and EBA175 (p < 0.0001) whereas IgG to variant surface antigens decreased with increasing age (p < 0.0001). However, the supplementation type did not have any impact on the prevalence or levels of antibodies at either 6 or 18 months of age to any of the tested malaria antigens in either univariate analysis or multivariate analysis after adjusting for covariates.ConclusionsPre- and postnatal lipid-based nutrient supplementation did not alter malaria antibody acquisition during infancy, compared to prenatal supplementation with iron and folic acid or pre- and postnatal supplementation with multiple micronutrients.Trail registeration Clinicaltrials.gov registration number NCT01239693