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Sobota RS, Goron AR, Berry AA, Bailey JA, Coulibaly D, Adams M, Kone AK, Kouriba B, Doumbo OK, Sztein MB, Felgner PL, Plowe CV, Lyke KE, Thera MA, Travassos MA. Serologic and Cytokine Profiles of Children with Concurrent Cerebral Malaria and Severe Malarial Anemia Are Distinct from Other Subtypes of Severe Malaria. Am J Trop Med Hyg 2022; 107:315-319. [PMID: 35895583 PMCID: PMC9393435 DOI: 10.4269/ajtmh.22-0135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 03/25/2022] [Indexed: 11/07/2022] Open
Abstract
We used a protein microarray featuring Plasmodium falciparum field variants of a merozoite surface antigen to examine malaria exposure in Malian children with different severe malaria syndromes. Unlike children with cerebral malaria alone or severe malarial anemia alone, those with concurrent cerebral malaria and severe malarial anemia had serologic responses demonstrating a broader prior parasite exposure pattern than matched controls with uncomplicated disease. Comparison of levels of malaria-related cytokines revealed that children with the concurrent phenotype had elevated levels of interleukin (IL)-6, IL-8, and IL-10. Our results suggest that the pathophysiology of this severe subtype is unique and merits further investigation.
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Affiliation(s)
- Rafal S. Sobota
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
- Ken and Ruth Davee Department of Neurology, Northwestern University, Chicago, Illinois
| | - Abby R. Goron
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Andrea A. Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jason A. Bailey
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Matthew Adams
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Abdoulaye K. Kone
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Ogobara K. Doumbo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Marcelo B. Sztein
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Philip L. Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, California
| | - Christopher V. Plowe
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Kirsten E. Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Mahamadou A. Thera
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Mark A. Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland
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2
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Zhou AE, Jain A, Nakajima R, Shrestha B, Stucke EM, Joshi S, Strauss KA, Hedde PN, Berry AA, Felgner PL, Travassos MA. Protein Microarrays as a Tool to Analyze Antibody Responses to Variant Surface Antigens Expressed on the Surface of Plasmodium falciparum-Infected Erythrocytes. Methods Mol Biol 2022. [PMID: 35881357 DOI: 10.1007/978-1-0716-2189-9_25/cover] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Enzyme-linked immunosorbent assays (ELISAs) remain the gold standard for measuring antibodies, but are time-consuming and use significant amounts of precious sample and reagents. Protein microarrays represent an appealing alternative, particularly for studies focused on large gene families such as those encoding variant surface antigens in the malaria parasite Plasmodium falciparum. Such microarrays represent an ideal high-throughput platform to study antibody responses to hundreds of malaria parasite variant surface antigens at once, providing critical insights into the development of natural immunity to malaria. We describe the essential background and approach to run an assay using a P. falciparum microarray populated with variant surface antigens. This allows the user to define serologic profiles and identify serodominant antigens that represent promising targets for vaccine or therapeutic development.
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Affiliation(s)
- Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aarti Jain
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Rie Nakajima
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Biraj Shrestha
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sudhaunshu Joshi
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathy A Strauss
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Per N Hedde
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Philip L Felgner
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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3
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Zhou AE, Jain A, Nakajima R, Shrestha B, Stucke EM, Joshi S, Strauss KA, Hedde PN, Berry AA, Felgner PL, Travassos MA. Protein Microarrays as a Tool to Analyze Antibody Responses to Variant Surface Antigens Expressed on the Surface of Plasmodium falciparum-Infected Erythrocytes. Methods Mol Biol 2022; 2470:343-358. [PMID: 35881357 DOI: 10.1007/978-1-0716-2189-9_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Enzyme-linked immunosorbent assays (ELISAs) remain the gold standard for measuring antibodies, but are time-consuming and use significant amounts of precious sample and reagents. Protein microarrays represent an appealing alternative, particularly for studies focused on large gene families such as those encoding variant surface antigens in the malaria parasite Plasmodium falciparum. Such microarrays represent an ideal high-throughput platform to study antibody responses to hundreds of malaria parasite variant surface antigens at once, providing critical insights into the development of natural immunity to malaria. We describe the essential background and approach to run an assay using a P. falciparum microarray populated with variant surface antigens. This allows the user to define serologic profiles and identify serodominant antigens that represent promising targets for vaccine or therapeutic development.
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Affiliation(s)
- Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Aarti Jain
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Rie Nakajima
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Biraj Shrestha
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sudhaunshu Joshi
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathy A Strauss
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Per N Hedde
- Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Philip L Felgner
- Vaccine R&D Center, Department of Physiology and Biophysics, University of California Irvine, Irvine, CA, USA
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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Immunoprofiles associated with controlled human malaria infection and naturally acquired immunity identify a shared IgA pre-erythrocytic immunoproteome. NPJ Vaccines 2021; 6:115. [PMID: 34518543 PMCID: PMC8438027 DOI: 10.1038/s41541-021-00363-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 07/29/2021] [Indexed: 12/12/2022] Open
Abstract
Knowledge of the Plasmodium falciparum antigens that comprise the human liver stage immunoproteome is important for pre-erythrocytic vaccine development, but, compared with the erythrocytic stage immunoproteome, more challenging to classify. Previous studies of P. falciparum antibody responses report IgG and rarely IgA responses. We assessed IgG and IgA antibody responses in adult sera collected during two controlled human malaria infection (CHMI) studies in malaria-naïve volunteers and in 1- to 6-year-old malaria-exposed Malian children on a 251 P. falciparum antigen protein microarray. IgG profiles in the two CHMI groups were equivalent and differed from Malian children. IgA profiles were robust in the CHMI groups and a subset of Malian children. We describe immunoproteome differences in naïve vs. exposed individuals and report pre-erythrocytic proteins recognized by the immune system. IgA responses detected in this study expand the list of pre-erythrocytic antigens for further characterization as potential vaccine candidates.
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Ventimiglia NT, Stucke EM, Coulibaly D, Berry AA, Lyke KE, Laurens MB, Bailey JA, Adams M, Niangaly A, Kone AK, Takala-Harrison S, Kouriba B, Doumbo OK, Felgner PL, Plowe CV, Thera MA, Travassos MA. Malian adults maintain serologic responses to virulent PfEMP1s amid seasonal patterns of fluctuation. Sci Rep 2021; 11:14401. [PMID: 34257318 PMCID: PMC8277812 DOI: 10.1038/s41598-021-92974-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Accepted: 06/08/2021] [Indexed: 12/03/2022] Open
Abstract
Plasmodium falciparum erythrocyte membrane protein-1s (PfEMP1s), diverse malaria proteins expressed on the infected erythrocyte surface, play an important role in pathogenesis, mediating adhesion to host vascular endothelium. Antibodies to particular non-CD36-binding PfEMP1s are associated with protection against severe disease. We hypothesized that given lifelong P. falciparum exposure, Malian adults would have broad PfEMP1 serorecognition and high seroreactivity levels during follow-up, particularly to non-CD36-binding PfEMP1s such as those that attach to endothelial protein C receptor (EPCR) and intercellular adhesion molecule-1 (ICAM-1). Using a protein microarray, we determined serologic responses to 166 reference PfEMP1 fragments during a dry and subsequent malaria transmission season in Malian adults. Malian adult sera had PfEMP1 serologic responses throughout the year, with decreased reactivity to a small subset of PfEMP1 fragments during the dry season and increases in reactivity to a different subset of PfEMP1 fragments during the subsequent peak malaria transmission season, especially for intracellular PfEMP1 domains. For some individuals, PfEMP1 serologic responses increased after the dry season, suggesting antigenic switching during asymptomatic infection. Adults were more likely to experience variable serorecognition of CD36-binding PfEMP1s than non-CD36-binding PfEMP1s that bind EPCR or ICAM-1, which remained serorecognized throughout the year. Sustained seroreactivity to non-CD36-binding PfEMP1s throughout adulthood amid seasonal fluctuation patterns may reflect underlying protective severe malaria immunity and merits further investigation.
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Affiliation(s)
| | - Emily M Stucke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Drissa Coulibaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Andrea A Berry
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kirsten E Lyke
- University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Jason A Bailey
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew Adams
- University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K Kone
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | | | - Bourema Kouriba
- University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Ogobara K Doumbo
- University of Sciences, Techniques and Technologies, Bamako, Mali
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6
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Gnidehou S, Yanow SK. VAR2CSA Antibodies in Non-Pregnant Populations. Trends Parasitol 2020; 37:65-76. [PMID: 33067131 DOI: 10.1016/j.pt.2020.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 09/16/2020] [Accepted: 09/18/2020] [Indexed: 11/18/2022]
Abstract
The Plasmodium falciparum protein VAR2CSA is a critical mediator of placental malaria, and VAR2CSA antibodies (IgGs) are important to protect pregnant women. Although infrequently detected outside pregnancy, VAR2CSA IgGs were reported in men and children from Colombia and Brazil and in select African populations. These findings raise questions about the specificity of VAR2CSA IgGs and the mechanisms by which they are acquired outside pregnancy. Here we review the data on VAR2CSA IgGs in men and children from different malaria-endemic regions. We discuss experimental factors that may affect interpretation of the serological data and consider the biological relevance of VAR2CSA IgGs in non-pregnant populations. We propose potential mechanisms for the acquisition of VARCSA IgGs outside of pregnancy. We identify knowledge gaps and research priorities.
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Affiliation(s)
- Sedami Gnidehou
- Campus Saint-Jean, University of Alberta, Edmonton, AB, Canada; Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.
| | - Stephanie K Yanow
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; School of Public Health, University of Alberta, Edmonton, AB, Canada
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7
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Stucke EM, Niangaly A, Berry AA, Bailey JA, Coulibaly D, Ouattara A, Lyke KE, Laurens MB, Dara A, Adams M, Pablo J, Jasinskas A, Nakajima R, Zhou AE, Agrawal S, Friedman-Klabanoff DJ, Takala-Harrison S, Kouriba B, Kone AK, Rowe JA, Doumbo OK, Felgner PL, Thera MA, Plowe CV, Travassos MA. Serologic responses to the PfEMP1 DBL-CIDR head structure may be a better indicator of malaria exposure than those to the DBL-α tag. Malar J 2019; 18:273. [PMID: 31409360 PMCID: PMC6692945 DOI: 10.1186/s12936-019-2905-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/05/2019] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP1) antigens play a critical role in host immune evasion. Serologic responses to these antigens have been associated with protection from clinical malaria, suggesting that antibodies to PfEMP1 antigens may contribute to natural immunity. The first N-terminal constitutive domain in a PfEMP1 is the Duffy binding-like alpha (DBL-α) domain, which contains a 300 to 400 base pair region unique to each particular protein (the DBL-α "tag"). This DBL-α tag has been used as a marker of PfEMP1 diversity and serologic responses in malaria-exposed populations. In this study, using sera from a malaria-endemic region, responses to DBL-α tags were compared to responses to the corresponding entire DBL-α domain (or "parent" domain) coupled with the succeeding cysteine-rich interdomain region (CIDR). METHODS A protein microarray populated with DBL-α tags, the parent DBL-CIDR head structures, and downstream PfEMP1 protein fragments was probed with sera from Malian children (aged 1 to 6 years) and adults from the control arms of apical membrane antigen 1 (AMA1) vaccine clinical trials before and during a malaria transmission season. Serological responses to the DBL-α tag and the DBL-CIDR head structure were measured and compared in children and adults, and throughout the season. RESULTS Malian serologic responses to a PfEMP1's DBL-α tag region did not correlate with seasonal malaria exposure, or with responses to the parent DBL-CIDR head structure in either children or adults. Parent DBL-CIDR head structures were better indicators of malaria exposure. CONCLUSIONS Larger PfEMP1 domains may be better indicators of malaria exposure than short, variable PfEMP1 fragments such as DBL-α tags. PfEMP1 head structures that include conserved sequences appear particularly well suited for study as serologic predictors of malaria exposure.
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Affiliation(s)
- Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Drissa Coulibaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Amed Ouattara
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kirsten E Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew B Laurens
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Antoine Dara
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Matthew Adams
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jozelyn Pablo
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Algis Jasinskas
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Rie Nakajima
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Albert E Zhou
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sonia Agrawal
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - DeAnna J Friedman-Klabanoff
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Abdoulaye K Kone
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - J Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Ogobara K Doumbo
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Philip L Felgner
- Division of Infectious Diseases, Department of Medicine, University of California, Irvine, CA, USA
| | - Mahamadou A Thera
- Malaria Research and Training Center, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | | | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA.
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Antibodies to Peptides in Semiconserved Domains of RIFINs and STEVORs Correlate with Malaria Exposure. mSphere 2019; 4:4/2/e00097-19. [PMID: 30894432 PMCID: PMC6429043 DOI: 10.1128/msphere.00097-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs. The repetitive interspersed family (RIFIN) and the subtelomeric variable open reading frame (STEVOR) family represent two of three major Plasmodium falciparum variant surface antigen families involved in malaria pathogenesis and immune evasion and are potential targets in the development of natural immunity. Protein and peptide microarrays populated with RIFINs and STEVORs associated with severe malaria vulnerability in Malian children were probed with adult and pediatric sera to identify epitopes that reflect malaria exposure. Adult sera recognized and reacted with greater intensity to all STEVOR proteins than pediatric sera did. Serorecognition of and seroreactivity to peptides within the semiconserved domain of STEVORs increased with age and seasonal malaria exposure, while serorecognition and seroreactivity increased for the semiconserved and second hypervariable domains of RIFINs only with age. Serologic responses to RIFIN and STEVOR peptides within the semiconserved domains may play a role in natural immunity to severe malaria. IMPORTANCE Malaria, an infectious disease caused by the parasite Plasmodium falciparum, causes nearly 435,000 deaths annually worldwide. RIFINs and STEVORs are two variant surface antigen families that are involved in malaria pathogenesis and immune evasion. Recent work has shown that a lack of humoral immunity to these proteins is associated with severe malaria vulnerability in Malian children. This is the first study to have compared serologic responses of children and adults to RIFINs and STEVORs in settings of malaria endemicity and to examine such serologic responses before and after a clinical malaria episode. Using microarrays, we determined that the semiconserved domains in these two parasite variant surface antigen families harbor peptides whose seroreactivity reflects malaria exposure. A similar approach has the potential to illuminate the role of variant surface antigens in the development of natural immunity to clinical malaria. Potential vaccines for severe malaria should include consideration of peptides within the semiconserved domains of RIFINs and STEVORs.
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9
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Children with cerebral malaria or severe malarial anaemia lack immunity to distinct variant surface antigen subsets. Sci Rep 2018; 8:6281. [PMID: 29674705 PMCID: PMC5908851 DOI: 10.1038/s41598-018-24462-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 03/28/2018] [Indexed: 01/08/2023] Open
Abstract
Variant surface antigens (VSAs) play a critical role in severe malaria pathogenesis. Defining gaps, or “lacunae”, in immunity to these Plasmodium falciparum antigens in children with severe malaria would improve our understanding of vulnerability to severe malaria and how protective immunity develops. Using a protein microarray with 179 antigen variants from three VSA families as well as more than 300 variants of three other blood stage P. falciparum antigens, reactivity was measured in sera from Malian children with cerebral malaria or severe malarial anaemia and age-matched controls. Sera from children with severe malaria recognized fewer extracellular PfEMP1 fragments and were less reactive to specific fragments compared to controls. Following recovery from severe malaria, convalescent sera had increased reactivity to certain non-CD36 binding PfEMP1s, but not other malaria antigens. Sera from children with severe malarial anaemia reacted to fewer VSAs than did sera from children with cerebral malaria, and both of these groups had lacunae in their seroreactivity profiles in common with children who had both cerebral malaria and severe malarial anaemia. This microarray-based approach may identify a subset of VSAs that could inform the development of a vaccine to prevent severe disease or a diagnostic test to predict at-risk children.
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10
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Dara A, Travassos MA, Adams M, Schaffer DeRoo S, Drábek EF, Agrawal S, Laufer MK, Plowe CV, Silva JC. A new method for sequencing the hypervariable Plasmodium falciparum gene var2csa from clinical samples. Malar J 2017; 16:343. [PMID: 28818101 PMCID: PMC5561619 DOI: 10.1186/s12936-017-1976-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 08/04/2017] [Indexed: 11/14/2022] Open
Abstract
Background VAR2CSA, a member of the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family, mediates the binding of P. falciparum-infected erythrocytes to chondroitin sulfate A, a surface-associated molecule expressed in placental cells, and plays a central role in the pathogenesis of placental malaria. VAR2CSA is a target of naturally acquired immunity and, as such, is a leading vaccine candidate against placental malaria. This protein is very polymorphic and technically challenging to sequence. Published var2csa sequences, mostly limited to specific domains, have been generated through the sequencing of cloned PCR amplicons using capillary electrophoresis, a method that is both time consuming and costly, and that performs poorly when applied to clinical samples that are commonly polyclonal. A next-generation sequencing platform, Pacific Biosciences (PacBio), offers an alternative approach to overcome these issues. Methods PCR primers were designed that target a 5 kb segment in the 5′ end of var2csa and the resulting amplicons were sequenced using PacBio sequencing. The primers were optimized using two laboratory strains and were validated on DNA from 43 clinical samples, extracted from dried blood spots on filter paper or from cryopreserved P. falciparum-infected erythrocytes. Sequence reads were assembled using the SMRT-analysis ConsensusTools module. Results Here, a PacBio sequencing-based approach for recovering a segment encoding the majority of VAR2CSA’s extracellular region is described; this segment includes the totality of the first four domains in the 5′ end of var2csa (~5 kb), from clinical malaria samples. The feasibility of the method is demonstrated, showing a high success rate from cryopreserved samples and more limited success from dried blood spots stored at room temperature, and characterized the genetic variation of the var2csa locus. Conclusions This method will facilitate a detailed analysis of var2csa genetic variation and can be adapted to sequence other hypervariable P. falciparum genes. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1976-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antoine Dara
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mark A Travassos
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew Adams
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sarah Schaffer DeRoo
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Elliott F Drábek
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sonia Agrawal
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Miriam K Laufer
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher V Plowe
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA. .,Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.
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11
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Dara A, Drábek EF, Travassos MA, Moser KA, Delcher AL, Su Q, Hostelley T, Coulibaly D, Daou M, Dembele A, Diarra I, Kone AK, Kouriba B, Laurens MB, Niangaly A, Traore K, Tolo Y, Fraser CM, Thera MA, Djimde AA, Doumbo OK, Plowe CV, Silva JC. New var reconstruction algorithm exposes high var sequence diversity in a single geographic location in Mali. Genome Med 2017; 9:30. [PMID: 28351419 PMCID: PMC5368897 DOI: 10.1186/s13073-017-0422-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 03/02/2017] [Indexed: 11/10/2022] Open
Abstract
Background Encoded by the var gene family, highly variable Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP1) proteins mediate tissue-specific cytoadherence of infected erythrocytes, resulting in immune evasion and severe malaria disease. Sequencing and assembling the 40–60 var gene complement for individual infections has been notoriously difficult, impeding molecular epidemiological studies and the assessment of particular var elements as subunit vaccine candidates. Methods We developed and validated a novel algorithm, Exon-Targeted Hybrid Assembly (ETHA), to perform targeted assembly of var gene sequences, based on a combination of Pacific Biosciences and Illumina data. Results Using ETHA, we characterized the repertoire of var genes in 12 samples from uncomplicated malaria infections in children from a single Malian village and showed them to be as genetically diverse as vars from isolates from around the globe. The gene var2csa, a member of the var family associated with placental malaria pathogenesis, was present in each genome, as were vars previously associated with severe malaria. Conclusion ETHA, a tool to discover novel var sequences from clinical samples, will aid the understanding of malaria pathogenesis and inform the design of malaria vaccines based on PfEMP1. ETHA is available at: https://sourceforge.net/projects/etha/. Electronic supplementary material The online version of this article (doi:10.1186/s13073-017-0422-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Antoine Dara
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Elliott F Drábek
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mark A Travassos
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kara A Moser
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Arthur L Delcher
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Qi Su
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Timothy Hostelley
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Modibo Daou
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Ahmadou Dembele
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Issa Diarra
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K Kone
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Matthew B Laurens
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Karim Traore
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Youssouf Tolo
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Claire M Fraser
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.,Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mahamadou A Thera
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye A Djimde
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Ogobara K Doumbo
- Malaria Research and Training Center, University of Science, Techniques and Technologies, Bamako, Mali
| | - Christopher V Plowe
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joana C Silva
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA. .,Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.
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12
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Charnaud SC, McGready R, Herten-Crabb A, Powell R, Guy A, Langer C, Richards JS, Gilson PR, Chotivanich K, Tsuboi T, Narum DL, Pimanpanarak M, Simpson JA, Beeson JG, Nosten F, Fowkes FJI. Maternal-foetal transfer of Plasmodium falciparum and Plasmodium vivax antibodies in a low transmission setting. Sci Rep 2016; 6:20859. [PMID: 26861682 PMCID: PMC4748262 DOI: 10.1038/srep20859] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/04/2016] [Indexed: 11/10/2022] Open
Abstract
During pregnancy immunoglobulin G (IgG) antibodies are transferred from mother to neonate across the placenta. Studies in high transmission areas have shown transfer of P. falciparum-specific IgG, but the extent and factors influencing maternal-foetal transfer in low transmission areas co-endemic for both P. falciparum and P. vivax are unknown. Pregnant women were screened weekly for Plasmodium infection. Mother-neonate paired serum samples at delivery were tested for IgG to antigens from P. falciparum, P. vivax and other infectious diseases. Antibodies to malarial and non-malarial antigens were highly correlated between maternal and neonatal samples (median [range] spearman ρ = 0.78 [0.57-0.93]), although Plasmodium spp. antibodies tended to be lower in neonates than mothers. Estimated gestational age at last P. falciparum infection, but not P. vivax infection, was positively associated with antibody levels in the neonate (P. falciparum merozoite, spearman ρ median [range] 0.42 [0.33-0.66], PfVAR2CSA 0.69; P. vivax ρ = 0.19 [0.09-0.3]). Maternal-foetal transfer of anti-malarial IgG to Plasmodium spp. antigens occurs in low transmission settings. P. vivax IgG acquisition is not associated with recent exposure unlike P. falciparum IgG, suggesting a difference in acquisition of antibodies. IgG transfer is greatest in the final weeks of pregnancy which has implications for the timing of future malaria vaccination strategies in pregnant women.
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Affiliation(s)
- Sarah C Charnaud
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia
| | - Rose McGready
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Asha Herten-Crabb
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia.,Department of Medicine, University of Melbourne, Australia
| | - Rosanna Powell
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia
| | - Andrew Guy
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia.,Department of Immunology, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Australia
| | - Christine Langer
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia
| | - Jack S Richards
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia.,Department of Medicine, University of Melbourne, Australia
| | - Paul R Gilson
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia
| | - Kesinee Chotivanich
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, Rockville, MD, USA
| | - Mupawjay Pimanpanarak
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, University of Melbourne, Australia
| | - James G Beeson
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia.,Department of Medicine, University of Melbourne, Australia
| | - François Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Freya J I Fowkes
- Macfarlane Burnet Institute of Medical Research, Melbourne, Australia.,Centre for Epidemiology and Biostatistics, University of Melbourne, Australia.,Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.,Department of Infectious Diseases, Monash University, Melbourne, Australia
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