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Kusi KA, Amoah LE, Acquah FK, Ennuson NA, Frempong AF, Ofori EA, Akyea-Mensah K, Kyei-Baafour E, Osei F, Frimpong A, Singh SK, Theisen M, Remarque EJ, Faber BW, Belmonte M, Ganeshan H, Huang J, Villasante E, Sedegah M. Plasmodium falciparum AMA1 and CSP antigen diversity in parasite isolates from southern Ghana. Front Cell Infect Microbiol 2024; 14:1375249. [PMID: 38808064 PMCID: PMC11132687 DOI: 10.3389/fcimb.2024.1375249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Accepted: 03/19/2024] [Indexed: 05/30/2024] Open
Abstract
Introduction Diversity in malarial antigens is an immune evasion mechanism that gives malaria parasites an edge over the host. Immune responses against one variant of a polymorphic antigen are usually not fully effective against other variants due to altered epitopes. This study aimed to evaluate diversity in the Plasmodium falciparum antigens apical membrane antigen 1 (PfAMA1) and circumsporozoite protein (PfCSP) from circulating parasites in a malaria-endemic community in southern Ghana and to determine the effects of polymorphisms on antibody response specificity. Methods The study involved 300 subjects, whose P. falciparum infection status was determined by microscopy and PCR. Diversity within the two antigens was evaluated by msp2 gene typing and molecular gene sequencing, while the host plasma levels of antibodies against PfAMA1, PfCSP, and two synthetic 24mer peptides from the conserved central repeat region of PfCSP, were measured by ELISA. Results Of the 300 subjects, 171 (57%) had P. falciparum infection, with 165 of the 171 (96.5%) being positive for either or both of the msp2 allelic families. Gene sequencing of DNA from 55 clonally infected samples identified a total of 56 non-synonymous single nucleotide polymorphisms (SNPs) for the Pfama1 gene and these resulted in 44 polymorphic positions, including two novel positions (363 and 365). Sequencing of the Pfcsp gene from 69 clonal DNA samples identified 50 non-synonymous SNPs that resulted in 42 polymorphic positions, with half (21) of these polymorphic positions being novel. Of the measured antibodies, only anti-PfCSP antibodies varied considerably between PCR parasite-positive and parasite-negative persons. Discussion These data confirm the presence of a considerable amount of unique, previously unreported amino acid changes, especially within PfCSP. Drivers for this diversity in the Pfcsp gene do not immediately seem apparent, as immune pressure will be expected to drive a similar level of diversity in the Pfama1 gene.
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Affiliation(s)
- Kwadwo A. Kusi
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Linda E. Amoah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Festus Kojo Acquah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Nana Aba Ennuson
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Abena F. Frempong
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Ebenezer A. Ofori
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Kwadwo Akyea-Mensah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Eric Kyei-Baafour
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Frank Osei
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Augustina Frimpong
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Susheel K. Singh
- Center for Medical Parasitology at the Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Congenital Diseases, Statens Serum Institut, Copenhagen, Denmark
| | - Michael Theisen
- Center for Medical Parasitology at the Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Congenital Diseases, Statens Serum Institut, Copenhagen, Denmark
| | - Edmond J. Remarque
- Department of Parasitology, Biomedical Primate Research Center, Rijswijk, Netherlands
| | - Bart W. Faber
- Department of Parasitology, Biomedical Primate Research Center, Rijswijk, Netherlands
| | - Maria Belmonte
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
- Malaria Department, Naval Medical Research Command, Silver Spring, MD, United States
| | - Harini Ganeshan
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
- Malaria Department, Naval Medical Research Command, Silver Spring, MD, United States
| | - Jun Huang
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., Bethesda, MD, United States
- Malaria Department, Naval Medical Research Command, Silver Spring, MD, United States
| | - Eileen Villasante
- Malaria Department, Naval Medical Research Command, Silver Spring, MD, United States
| | - Martha Sedegah
- Malaria Department, Naval Medical Research Command, Silver Spring, MD, United States
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Winnicki AC, Dietrich MH, Yeoh LM, Carias LL, Roobsoong W, Drago CL, Malachin AN, Redinger KR, Feufack-Donfack LB, Baldor L, Jung NC, McLaine OS, Skomorovska-Prokvolit Y, Orban A, Opi DH, Sattabongkot J, Tham WH, Popovici J, Beeson JG, Bosch J, King CL. Potent AMA1-specific human monoclonal antibody against P. vivax Pre-erythrocytic and Blood Stages. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.07.579302. [PMID: 38370683 PMCID: PMC10871283 DOI: 10.1101/2024.02.07.579302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
New therapeutics are a priority for preventing and eliminating Plasmodium vivax (Pv) malaria because of its easy transmissibility and dormant stages in the liver. Relapses due to the dormant liver stages are the major contributor to reoccurring Pv. Therefore, therapies that reduce the establishment of dormant parasites and blood-stage infection are important for controlling this geographically widespread parasite. Here, we isolated 12 human monoclonal antibodies (humAbs) from the plasma of a Pv-exposed individual that recognized Pv apical membrane antigen 1 (PvAMA1). PvAMA1 is important for both sporozoite invasion of hepatocytes and merozoite invasion of reticulocytes. We identified one humAb, 826827, that blocked invasion of human erythrocytes using a transgenic P. falciparum line expressing PvAMA1 (IC 50 = 3 µg/mL) and all Pv clinical isolates in vitro . This humAb also inhibited sporozoite invasion of a human hepatocyte cell line and primary human hepatocytes (IC 50 of 0.3 - 3.7 µg/mL). The crystal structure of recombinant PvAMA1 with the antigen-binding fragment of 826827 at 2.4 Å resolution shows that the humAb partially occupies the highly conserved hydrophobic groove in PvAMA1 that binds its known receptor, RON2. HumAb 826827 binds to PvAMA1 with higher affinity than RON2, accounting for its potency. To our knowledge, this is the first reported humAb specific to PvAMA1, and the PvAMA1 residues it binds to are highly conserved across different isolates, explaining its strain-transcendent properties.
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Patel PN, Dickey TH, Diouf A, Salinas ND, McAleese H, Ouahes T, Long CA, Miura K, Lambert LE, Tolia NH. Structure-based design of a strain transcending AMA1-RON2L malaria vaccine. Nat Commun 2023; 14:5345. [PMID: 37660103 PMCID: PMC10475129 DOI: 10.1038/s41467-023-40878-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 08/14/2023] [Indexed: 09/04/2023] Open
Abstract
Apical membrane antigen 1 (AMA1) is a key malaria vaccine candidate and target of neutralizing antibodies. AMA1 binds to a loop in rhoptry neck protein 2 (RON2L) to form the moving junction during parasite invasion of host cells, and this complex is conserved among apicomplexan parasites. AMA1-RON2L complex immunization achieves higher growth inhibitory activity than AMA1 alone and protects mice against Plasmodium yoelii challenge. Here, three single-component AMA1-RON2L immunogens were designed that retain the structure of the two-component AMA1-RON2L complex: one structure-based design (SBD1) and two insertion fusions. All immunogens elicited high antibody titers with potent growth inhibitory activity, yet these antibodies did not block RON2L binding to AMA1. The SBD1 immunogen induced significantly more potent strain-transcending neutralizing antibody responses against diverse strains of Plasmodium falciparum than AMA1 or AMA1-RON2L complex vaccination. This indicates that SBD1 directs neutralizing antibody responses to strain-transcending epitopes in AMA1 that are independent of RON2L binding. This work underscores the importance of neutralization mechanisms that are distinct from RON2 blockade. The stable single-component SBD1 immunogen elicits potent strain-transcending protection that may drive the development of next-generation vaccines for improved malaria and apicomplexan parasite control.
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Affiliation(s)
- Palak N Patel
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Thayne H Dickey
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Ababacar Diouf
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Nichole D Salinas
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Holly McAleese
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Tarik Ouahes
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Carole A Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Lynn E Lambert
- Vaccine Development Unit, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Niraj H Tolia
- Host-Pathogen Interactions and Structural Vaccinology Section, Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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Núñez A, Ntumngia FB, Guerra Y, Adams JH, Sáenz FE. Genetic diversity and natural selection of Plasmodium vivax reticulocyte invasion genes in Ecuador. Malar J 2023; 22:225. [PMID: 37537581 PMCID: PMC10398936 DOI: 10.1186/s12936-023-04640-0] [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] [Received: 01/25/2023] [Accepted: 07/04/2023] [Indexed: 08/05/2023] Open
Abstract
BACKGROUND Knowledge of the diversity of invasion ligands in malaria parasites in endemic regions is essential to understand how natural selection influences genetic diversity of these ligands and their feasibility as possible targets for future vaccine development. In this study the diversity of four genes for merozoite invasion ligands was studied in Ecuadorian isolates of Plasmodium vivax. METHODS Eighty-eight samples from P. vivax infected individuals from the Coast and Amazon region of Ecuador were obtained between 2012 and 2015. The merozoite invasion genes pvmsp-1-19, pvdbpII, pvrbp1a-2 and pvama1 were amplified, sequenced, and compared to the Sal-1 strain. Polymorphisms were mapped and genetic relationships between haplotypes were determined. RESULTS Only one nonsynonymous polymorphism was detected in pvmsp-1-19, while 44 nonsynonymous polymorphisms were detected in pvdbpII, 56 in pvrbp1a-2 and 33 in pvama1. While haplotypes appeared to be more related within each area of study and there was less relationship between parasites of the coastal and Amazon regions of the country, diversification processes were observed in the two Amazon regions. The highest haplotypic diversity for most genes occurred in the East Amazon of the country. The high diversity observed in Ecuadorian samples is closer to Brazilian and Venezuelan isolates, but lower than reported in other endemic regions. In addition, departure from neutrality was observed in Ecuadorian pvama1. Polymorphisms for pvdbpII and pvama1 were associated to B-cell epitopes. CONCLUSIONS pvdbpII and pvama1 genetic diversity found in Ecuadorian P. vivax was very similar to that encountered in other malaria endemic countries with varying transmission levels and segregated by geographic region. The highest diversity of P. vivax invasion genes in Ecuador was found in the Amazonian region. Although selection appeared to have small effect on pvdbpII and pvrbp1a-2, pvama1 was influenced by significant balancing selection.
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Affiliation(s)
- Andrés Núñez
- Centro de Investigación para la Salud en América Latina, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador
| | - Francis B Ntumngia
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, FL, Tampa, USA
| | - Yasel Guerra
- Grupo de Bio-Quimioinformática, Universidad de Las Américas, Quito, Ecuador
| | - John H Adams
- Center for Global Health and Interdisciplinary Research, College of Public Health, University of South Florida, FL, Tampa, USA
| | - Fabián E Sáenz
- Centro de Investigación para la Salud en América Latina, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Quito, Ecuador.
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da Veiga GTS, Moriggi MR, Vettorazzi JF, Müller-Santos M, Albrecht L. Plasmodium vivax vaccine: What is the best way to go? Front Immunol 2023; 13:910236. [PMID: 36726991 PMCID: PMC9885200 DOI: 10.3389/fimmu.2022.910236] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 12/23/2022] [Indexed: 01/18/2023] Open
Abstract
Malaria is one of the most devastating human infectious diseases caused by Plasmodium spp. parasites. A search for an effective and safe vaccine is the main challenge for its eradication. Plasmodium vivax is the second most prevalent Plasmodium species and the most geographically distributed parasite and has been neglected for decades. This has a massive gap in knowledge and consequently in the development of vaccines. The most significant difficulties in obtaining a vaccine against P. vivax are the high genetic diversity and the extremely complex life cycle. Due to its complexity, studies have evaluated P. vivax antigens from different stages as potential targets for an effective vaccine. Therefore, the main vaccine candidates are grouped into preerythrocytic stage vaccines, blood-stage vaccines, and transmission-blocking vaccines. This review aims to support future investigations by presenting the main findings of vivax malaria vaccines to date. There are only a few P. vivax vaccines in clinical trials, and thus far, the best protective efficacy was a vaccine formulated with synthetic peptide from a circumsporozoite protein and Montanide ISA-51 as an adjuvant with 54.5% efficacy in a phase IIa study. In addition, the majority of P. vivax antigen candidates are polymorphic, induce strain-specific and heterogeneous immunity and provide only partial protection. Nevertheless, immunization with recombinant proteins and multiantigen vaccines have shown promising results and have emerged as excellent strategies. However, more studies are necessary to assess the ideal vaccine combination and test it in clinical trials. Developing a safe and effective vaccine against vivax malaria is essential for controlling and eliminating the disease. Therefore, it is necessary to determine what is already known to propose and identify new candidates.
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Affiliation(s)
- Gisele Tatiane Soares da Veiga
- Laboratory of Apicomplexan Parasites Research, Carlos Chagas Institute, Oswaldo Cruz Foundation (FIOCRUZ), Curitiba, Brazil,Nitrogen Fixation Laboratory, Department of Biochemistry and Molecular Biology, Federal University of Paraná (UFPR), Curitiba, Brazil
| | | | | | - Marcelo Müller-Santos
- Nitrogen Fixation Laboratory, Department of Biochemistry and Molecular Biology, Federal University of Paraná (UFPR), Curitiba, Brazil
| | - Letusa Albrecht
- Laboratory of Apicomplexan Parasites Research, Carlos Chagas Institute, Oswaldo Cruz Foundation (FIOCRUZ), Curitiba, Brazil,*Correspondence: Letusa Albrecht,
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Ng YL, Lee WC, Lau YL, Fong MY. The Impact of Geographical Variation in Plasmodium knowlesi Apical Membrane Protein 1 (PkAMA-1) on Invasion Dynamics of P. knowlesi. Trop Med Infect Dis 2023; 8:tropicalmed8010056. [PMID: 36668963 PMCID: PMC9863575 DOI: 10.3390/tropicalmed8010056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/16/2022] [Accepted: 01/08/2023] [Indexed: 01/12/2023] Open
Abstract
Plasmodium knowlesi has emerged as an important zoonotic parasite that causes persistent symptomatic malaria in humans. The signs and symptoms of malaria are attributed to the blood stages of the parasites, which start from the invasion of erythrocytes by the blood stage merozoites. The apical membrane protein 1 (AMA-1) plays an important role in the invasion. In this study, we constructed and expressed recombinant PkAMA-1 domain II (PkAMA-1-DII) representing the predominant haplotypes from Peninsular Malaysia and Malaysian Borneo and raised specific antibodies against the recombinant proteins in rabbits. Despite the minor amino acid sequence variation, antibodies raised against haplotypes from Peninsular Malaysia and Malaysian Borneo demonstrated different invasion inhibition (46.81% and 39.45%, respectively) to P. knowlesi A1-H.1, a reference strain derived from Peninsular Malaysia. Here, we demonstrated how a minor variation in a conserved parasite protein could cast a significant impact on parasite invasion biology, suggesting a complex host-switching of P. knowlesi from different locations. This may challenge the implementation of a standardized One Health approach against the transmission of knowlesi malaria.
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Affiliation(s)
- Yee Ling Ng
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Wenn-Chyau Lee
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- A*STAR Infectious Diseases Labs, Agency for Science, Technology and Research (A*STAR), Singapore 138648, Singapore
| | - Yee-Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence:
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Cova MM, Lamarque MH, Lebrun M. How Apicomplexa Parasites Secrete and Build Their Invasion Machinery. Annu Rev Microbiol 2022; 76:619-640. [PMID: 35671531 DOI: 10.1146/annurev-micro-041320-021425] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Apicomplexa are obligatory intracellular parasites that sense and actively invade host cells. Invasion is a conserved process that relies on the timely and spatially controlled exocytosis of unique specialized secretory organelles termed micronemes and rhoptries. Microneme exocytosis starts first and likely controls the intricate mechanism of rhoptry secretion. To assemble the invasion machinery, micronemal proteins-associated with the surface of the parasite-interact and form complexes with rhoptry proteins, which in turn are targeted into the host cell. This review covers the molecular advances regarding microneme and rhoptry exocytosis and focuses on how the proteins discharged from these two compartments work in synergy to drive a successful invasion event. Particular emphasis is given to the structure and molecular components of the rhoptry secretion apparatus, and to the current conceptual framework of rhoptry exocytosis that may constitute an unconventional eukaryotic secretory machinery closely related to the one described in ciliates. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Marta Mendonça Cova
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
| | - Mauld H Lamarque
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
| | - Maryse Lebrun
- Laboratory of Pathogen Host Interactions (LPHI), CNRS, University of Montpellier, Montpellier, France;
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Cui YB, Shen HM, Chen SB, Kassegne K, Shi TQ, Xu B, Chen JH, Wu JH, Wang Y. Genetic Diversity and Selection of Plasmodium vivax Apical Membrane Antigen-1 in China-Myanmar Border of Yunnan Province, China, 2009-2016. Front Cell Infect Microbiol 2022; 11:742189. [PMID: 35071030 PMCID: PMC8766981 DOI: 10.3389/fcimb.2021.742189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 12/09/2021] [Indexed: 11/26/2022] Open
Abstract
Plasmodium vivax apical membrane antigen-1 (PvAMA-1) is an important vaccine candidate for vivax malaria. However, antigenic variation within PvAMA-1 is a major obstacle to the design of a global protective malaria vaccine. In this study, we analyzed the genetic polymorphism and selection of the PvAMA-1 gene from 152 P. vivax isolates from imported cases to China, collected in the China–Myanmar border (CMB) area in Yunnan Province (YP) during 2009–2011 (n = 71) and 2014–2016 (n = 81), in comparison with PvAMA-1 gene information from Myanmar (n = 73), collected from public data. The overall nucleotide diversity of the PvAMA-1 gene from the 152 YP isolates was 0.007 with 76 haplotypes identified (Hd = 0.958). Results from the population structure suggested three groups among the YP and Myanmar isolates with optimized clusters value of K = 7. In addition, YP (2014–2016) isolates generally lacked some K components that were commonly found in YP (2009–2011) and Myanmar. Meanwhile, PvAMA-1 domain I is found to be the dominant target of positive diversifying selection and most mutation loci were found in this domain. The mutation frequencies of D107N/A, R112K/T, K120R, E145A, E277K, and R438H in PvAMA-1 were more than 70% in the YP isolates. In conclusion, high genetic diversity and positive selection were found in the PvAMA-1 gene from YP isolates, which are significant findings for the design and development of PvAMA-1-based malaria vaccine.
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Affiliation(s)
- Yan-Bing Cui
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China
| | - Hai-Mo Shen
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China
| | - Shen-Bo Chen
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China
| | - Kokouvi Kassegne
- School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tian-Qi Shi
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China
| | - Bin Xu
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China
| | - Jun-Hu Chen
- National Institute of Parasitic Diseases, Chinese Center for Diseases Control and Prevention (Chinese Center for Tropical Diseases Research), Shanghai, China.,National Health Commission of the People's Republic of China (NHC) Key Laboratory of Parasite and Vector Biology, Shanghai, China.,World Health Organization (WHO) Collaborating Center for Tropical Diseases, Shanghai, China.,National Center for International Research on Tropical Diseases, Shanghai, China.,School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jia-Hong Wu
- Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang, China.,Department of Parasitology, Provincial Key Laboratory of Modern Pathogen Biology, Guizhou Medical University, Guiyang, China
| | - Yue Wang
- Institute of Parasitic Diseases, School of Basic Medical Sciences and Forensic Medicine, Hangzhou Medical College, Hangzhou, China
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9
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Rittipornlertrak A, Nambooppha B, Muenthaisong A, Punyapornwithaya V, Tiwananthagorn S, Chung YT, Tuvshintulga B, Sivakumar T, Yokoyama N, Sthitmatee N. Structural and immunological characterization of an epitope within the PAN motif of ectodomain I in Babesia bovis apical membrane antigen 1 for vaccine development. PeerJ 2021; 9:e11765. [PMID: 34316404 PMCID: PMC8288113 DOI: 10.7717/peerj.11765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 06/22/2021] [Indexed: 11/25/2022] Open
Abstract
Background Bovine babesiosis caused by Babesia bovis (B. bovis) has had a significant effect on the mobility and mortality rates of the cattle industry worldwide. Live-attenuated vaccines are currently being used in many endemic countries, but their wide use has been limited for a number of reasons. Although recombinant vaccines have been proposed as an alternative to live vaccines, such vaccines are not commercially available to date. Apical membrane antigen-1 (AMA-1) is one of the leading candidates in the development of a vaccine against diseases caused by apicomplexan parasite species. In Plasmodium falciparum (P. falciparum) AMA-1 (PfAMA-1), several antibodies against epitopes in the plasminogen, apple, and nematode (PAN) motif of PfAMA-1 domain I significantly inhibited parasite growth. Therefore, the purpose of this study was to predict an epitope from the PAN motif of domain I in the B. bovis AMA-1 (BbAMA-1) using a combination of linear and conformational B-cell epitope prediction software. The selected epitope was then bioinformatically analyzed, synthesized as a peptide (sBbAMA-1), and then used to immunize a rabbit. Subsequently, in vitro growth- and the invasion-inhibitory effects of the rabbit antiserum were immunologically characterized. Results Our results demonstrated that the predicted BbAMA-1 epitope was located on the surface-exposed α-helix of the PAN motif in domain I at the apex area between residues 181 and 230 with six polymorphic sites. Subsequently, sBbAMA-1 elicited antibodies capable of recognizing the native BbAMA-1 in immunoassays. Furthermore, anti-serum against sBbAMA-1 was immunologically evaluated for its growth- and invasion-inhibitory effects on B. bovis merozoites in vitro. Our results demonstrated that the rabbit anti-sBbAMA-1 serum at a dilution of 1:5 significantly inhibited (p < 0.05) the growth of B. bovis merozoites by approximately 50–70% on days 3 and 4 of cultivation, along with the invasion of merozoites by approximately 60% within 4 h of incubation when compared to the control groups. Conclusion Our results indicate that the epitope predicted from the PAN motif of BbAMA-1 domain I is neutralization-sensitive and may serve as a target antigen for vaccine development against bovine babesiosis caused by B. bovis.
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Affiliation(s)
| | - Boondarika Nambooppha
- Graduate School of Veterinary Sciences, Chiang Mai University, Muang, Chiang Mai, Thailand
| | - Anucha Muenthaisong
- Graduate School of Veterinary Sciences, Chiang Mai University, Muang, Chiang Mai, Thailand
| | - Veerasak Punyapornwithaya
- Department of Food Animal Clinic, Faculty of Veterinary Medicine, Chiang Mai University, Muang, Chiang Mai, Thailand
| | - Saruda Tiwananthagorn
- Department of Veterinary Bioscience and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Muang, Chiang Mai, Thailand
| | - Yang-Tsung Chung
- Department of Veterinary Medicine, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taichung, Taiwan
| | - Bumduuren Tuvshintulga
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Thillaiampalam Sivakumar
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Naoaki Yokoyama
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
| | - Nattawooti Sthitmatee
- Department of Veterinary Bioscience and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, Muang, Chiang Mai, Thailand
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10
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França ACB, Françoso KS, Marques RF, Trossini GHG, Gomes RA, Póvoa MM, Cunha MG, Silveira ELV, Soares IS. Antibodies Against the Plasmodium vivax Apical Membrane Antigen 1 From the Belem Strain Share Common Epitopes Among Other Worldwide Variants. Front Cell Infect Microbiol 2021; 11:616230. [PMID: 33796476 PMCID: PMC8009186 DOI: 10.3389/fcimb.2021.616230] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 02/23/2021] [Indexed: 12/31/2022] Open
Abstract
Malaria is a human parasitic disease distributed in many tropical countries and caused by various Plasmodium species. Plasmodium vivax has the largest geographical distribution of the Plasmodium species and is predominant in the Americas, including Brazil. Only a small number of P. vivax vaccine formulations have successfully reached clinical trials relative to their P. falciparum counterparts. One of the candidate antigens for a blood-stage P. vivax vaccine is apical membrane antigen 1 (PvAMA-1). Due to the worldwide distribution of Plasmodium parasites, a high degree of variability has been detected in this antigen sequence, representing a considerable challenge to the development of a universal vaccine against malaria. In this study, we evaluated how PvAMA-1 polymorphisms influence vaccine-derived immune responses in P. vivax malaria. To this end, we expressed 9 recombinant protein representatives of different PvAMA-1 allelic variants in the yeast Pichia pastoris: Belem, Chesson I, Sal-1, Indonesia XIX, SK0814, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS. After protein expression and purification, we evaluated the breadth of the immune responses derived from malaria-exposed individuals from the Amazon region. From 611 serum samples of malaria-exposed individuals, 53.68% of them reacted against the PvAMA-1 Belem through ELISA. Positive samples were further tested against recombinant proteins representing the other PvAMA-1 allelic variants. Whereas Sal-1, Chesson I and SK0814 variants were highly recognized by tested serum samples, Indonesia XIX, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS were only slightly recognized. Moreover, polyclonal sera derived from C57BL/6 mice immunized with the PvAMA-1 Belem protein predominantly recognized Belem, Sal-1, Chesson I, SK0814, and Indonesia XIX through ELISA. Last, ELISA-based competition assays demonstrated that a previous interaction between anti-Belem polyclonal serum and Sal-1, Chesson I, SK0814, or Indonesia XIX proteins could further inhibit antibody binding to the Belem variant. Our human and mouse data suggest the presence of common epitopes or cross-reactivity between Belem, Sal-1, Chesson I, and SK0814 variants. Although the PvAMA-1 Belem variant induces strain-transcendent antibodies, PvAMA-1 variants from Thailand and Papua New Guinea may need to be included in a universal vaccine formulation to achieve protection against P. vivax malaria.
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Affiliation(s)
- Ana Caroline Barbosa França
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Kátia Sanches Françoso
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Rodolfo Ferreira Marques
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Gustavo H. G. Trossini
- Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Renan A. Gomes
- Department of Pharmacy, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Maristela G. Cunha
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brazil
| | - Eduardo L. V. Silveira
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Irene S. Soares
- Department of Clinical and Toxicological Analyses, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
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11
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De SL, Ntumngia FB, Nicholas J, Adams JH. Progress towards the development of a P. vivax vaccine. Expert Rev Vaccines 2021; 20:97-112. [PMID: 33481638 PMCID: PMC7994195 DOI: 10.1080/14760584.2021.1880898] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 01/21/2021] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Plasmodium vivax causes significant public health problems in endemic regions. A vaccine to prevent disease is critical, considering the rapid spread of drug-resistant parasite strains, and the development of hypnozoites in the liver with potential for relapse. A minimally effective vaccine should prevent disease and transmission while an ideal vaccine provides sterile immunity. AREAS COVERED Despite decades of research, the complex life cycle, technical challenges and a lack of funding have hampered progress of P. vivax vaccine development. Here, we review the progress of potential P. vivax vaccine candidates from different stages of the parasite life cycle. We also highlight the challenges and important strategies for rational vaccine design. These factors can significantly increase immune effector mechanisms and improve the protective efficacy of these candidates in clinical trials to generate sustained protection over longer periods of time. EXPERT OPINION A vaccine that presents functionally-conserved epitopes from multiple antigens from various stages of the parasite life cycle is key to induce broadly neutralizing strain-transcending protective immunity to effectively disrupt parasite development and transmission.
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Affiliation(s)
- Sai Lata De
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - Francis B. Ntumngia
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - Justin Nicholas
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
| | - John H. Adams
- Center for Global Health and Infectious Diseases Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd, Tampa – 33612, FL
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12
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Wang Q, Zhu S, Zhao Q, Huang B, Yu S, Yu Y, Liang S, Wang H, Zhao H, Han H, Dong H. Identification and Characterization of a Novel Apical Membrane Antigen 3 in Eimeria tenella. J Eukaryot Microbiol 2021; 68:e12836. [PMID: 33289220 DOI: 10.1111/jeu.12836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/16/2022]
Abstract
Eimeria tenella is an obligate intracellular parasite in the phylum Apicomplexa. As described for other members of Apicomplexa, apical membrane antigen 1 (AMA1) has been shown to be critical for sporozoite invasion of host cells by E. tenella. Recently, an E. tenella paralogue of AMA1 (EtAMA1), dubbed sporoAMA1 (EtAMA3), was identified in proteomic and transcriptomic analyses of E. tenella, but not further characterized. Here, we show that EtAMA3 is a type I integral membrane protein that has 24% -38% identity with other EtAMAs. EtAMA3 has the same pattern of Cys residues in domains I and II of AMA1 orthologs from apicomplexan parasites, but high variance in domain III, with all six invariant Cys residues absent. EtAMA3 expression was developmentally regulated at the mRNA and protein levels. EtAMA3 protein was detected in sporulated oocysts and sporozoites, but not in the unsporulated oocysts or second-generation merozoites. EtAMA3 is secreted by micronemes and is primarily localized to the apical end of sporozoites during host-cell invasion. Additionally, pretreatment of sporozoites with rEtAMA3-specific antibodies substantially impeded their invasion into host cells. These results suggest EtAMA3 is a sporozoite-specific protein that is involved in host-cell sporozoite invasion.
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Affiliation(s)
- Qingjie Wang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Shunhai Zhu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Qiping Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Bing Huang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Shuilan Yu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Yu Yu
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Shanshan Liang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Haixia Wang
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Huanzhi Zhao
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Hongyu Han
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
| | - Hui Dong
- Key Laboratory of Animal Parasitology of Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, Shanghai, 200241, China
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13
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Wang Q, Zhao Q, Zhu S, Huang B, Yu S, Liang S, Wang H, Zhao H, Han H, Dong H. Further investigation of the characteristics and biological function of Eimeria tenella apical membrane antigen 1. ACTA ACUST UNITED AC 2020; 27:70. [PMID: 33306022 PMCID: PMC7731912 DOI: 10.1051/parasite/2020068] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 11/20/2020] [Indexed: 12/20/2022]
Abstract
Apical membrane antigen 1 (AMA1) is a type I integral membrane protein that is highly conserved in apicomplexan parasites. Previous studies have shown that Eimeria tenella AMA1 (EtAMA1) is critical for sporozoite invasion of host cells. Here, we show that EtAMA1 is a microneme protein secreted by sporozoites, confirming previous results. Individual and combined treatment with antibodies of EtAMA1 and its interacting proteins, E. tenella rhoptry neck protein 2 (EtRON2) and Eimeria-specific protein (EtESP), elicited significant anti-invasion effects on the parasite in a concentration-dependent manner. The overexpression of EtAMA1 in DF-1 cells showed a significant increase of sporozoite invasion. Isobaric tags for relative and absolute quantitation (iTRAQ) coupled with LC-MS/MS were used to screen differentially expressed proteins (DEPs) in DF-1 cells transiently transfected with EtAMA1. In total, 3953 distinct nonredundant proteins were identified and 163 of these were found to be differentially expressed, including 91 upregulated proteins and 72 downregulated proteins. The DEPs were mainly localized within the cytoplasm and were involved in protein binding and poly(A)-RNA binding. KEEG analyses suggested that the key pathways that the DEPs belonged to included melanogenesis, spliceosomes, tight junctions, and the FoxO and MAPK signaling pathways. The data in this study not only provide a comprehensive dataset for the overall protein changes caused by EtAMA1 expression, but also shed light on EtAMA1’s potential molecular mechanisms during Eimeria infections.
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Affiliation(s)
- Qingjie Wang
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Qiping Zhao
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Shunhai Zhu
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Bing Huang
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Shuilan Yu
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Shanshan Liang
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Haixia Wang
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Huanzhi Zhao
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Hongyu Han
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
| | - Hui Dong
- Key Laboratory of Animal Parasitology of the Ministry of Agriculture, Shanghai Veterinary Research Institute, CAAS, 200241 Shanghai, PR China
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14
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Collins CR, Hackett F, Howell SA, Snijders AP, Russell MRG, Collinson LM, Blackman MJ. The malaria parasite sheddase SUB2 governs host red blood cell membrane sealing at invasion. eLife 2020; 9:e61121. [PMID: 33287958 PMCID: PMC7723409 DOI: 10.7554/elife.61121] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/26/2020] [Indexed: 12/26/2022] Open
Abstract
Red blood cell (RBC) invasion by malaria merozoites involves formation of a parasitophorous vacuole into which the parasite moves. The vacuole membrane seals and pinches off behind the parasite through an unknown mechanism, enclosing the parasite within the RBC. During invasion, several parasite surface proteins are shed by a membrane-bound protease called SUB2. Here we show that genetic depletion of SUB2 abolishes shedding of a range of parasite proteins, identifying previously unrecognized SUB2 substrates. Interaction of SUB2-null merozoites with RBCs leads to either abortive invasion with rapid RBC lysis, or successful entry but developmental arrest. Selective failure to shed the most abundant SUB2 substrate, MSP1, reduces intracellular replication, whilst conditional ablation of the substrate AMA1 produces host RBC lysis. We conclude that SUB2 activity is critical for host RBC membrane sealing following parasite internalisation and for correct functioning of merozoite surface proteins.
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Affiliation(s)
- Christine R Collins
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Fiona Hackett
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
| | - Steven A Howell
- Protein Analysis and Proteomics Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Ambrosius P Snijders
- Protein Analysis and Proteomics Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Matthew RG Russell
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Lucy M Collinson
- Electron Microscopy Science Technology Platform, The Francis Crick InstituteLondonUnited Kingdom
| | - Michael J Blackman
- Malaria Biochemistry Laboratory, The Francis Crick InstituteLondonUnited Kingdom
- Faculty of Infectious Diseases, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
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15
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Bittencourt NC, da Silva ABIE, Virgili NS, Schappo AP, Gervásio JHDB, Pimenta TS, Kujbida Junior MA, Ventura AMRS, Libonati RMF, Silva-Filho JL, dos Santos HG, Lopes SCP, Lacerda MVG, Machado RLD, Costa FTM, Albrecht L. Plasmodium vivax AMA1: Implications of distinct haplotypes for immune response. PLoS Negl Trop Dis 2020; 14:e0008471. [PMID: 32639964 PMCID: PMC7371208 DOI: 10.1371/journal.pntd.0008471] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 07/20/2020] [Accepted: 06/10/2020] [Indexed: 02/07/2023] Open
Abstract
In Brazil, Plasmodium vivax infection accounts for around 80% of malaria cases. This infection has a substantial impact on the productivity of the local population as the course of the disease is usually prolonged and the development of acquired immunity in endemic areas takes several years. The recent emergence of drug-resistant strains has intensified research on alternative control methods such as vaccines. There is currently no effective available vaccine against malaria; however, numerous candidates have been studied in the past several years. One of the leading candidates is apical membrane antigen 1 (AMA1). This protein is involved in the invasion of Apicomplexa parasites into host cells, participating in the formation of a moving junction. Understanding how the genetic diversity of an antigen influences the immune response is highly important for vaccine development. In this study, we analyzed the diversity of AMA1 from Brazilian P. vivax isolates and 19 haplotypes of P. vivax were found. Among those sequences, 33 nonsynonymous PvAMA1 amino acid sites were identified, whereas 20 of these sites were determined to be located in predicted B-cell epitopes. Nonsynonymous mutations were evaluated for their influence on the immune recognition of these antigens. Two distinct haplotypes, 5 and 16, were expressed and evaluated for reactivity in individuals from northern Brazil. Both PvAMA1 variants were reactive. Moreover, the IgG antibody response to these two PvAMA1 variants was analyzed in an exposed but noninfected population from a P. vivax endemic area. Interestingly, over 40% of this population had antibodies recognizing both variants. These results have implications for the design of a vaccine based on a polymorphic antigen. Plasmodium vivax is the most abundant Plasmodium species in Brazil. While this species has been neglected for many years, the recent emergence of drug-resistant strains and the absence of a vaccine intensified the efforts for a better control method. Naturally acquired immune response analysis is a useful tool for understanding the antigenicity of Plasmodium proteins and evaluating the potential of a vaccine candidate. In this study, the genetic variability of one of the leading P. vivax vaccine candidates (PvAMA1) was analyzed. Two distinct variants were expressed and the antibody response was evaluated in infected and noninfected individuals in the Brazilian Amazon. This improved understanding of the magnitude and dynamics of the antibody response will contribute to the knowledge of a vaccine candidate and open new perspectives in vivax malaria vaccine development.
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Affiliation(s)
- Najara Carneiro Bittencourt
- Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | | | - Natália Silveira Virgili
- Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Ana Paula Schappo
- Instituto Carlos Chagas, Fundação Oswaldo Cruz–FIOCRUZ. Curitiba, PR, Brazil
| | | | - Tamirys S. Pimenta
- Núcleo de Medicina Tropical, Universidade Federal do Pará, Belém, PA, Brazil
| | | | | | | | - João Luiz Silva-Filho
- Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | | | - Stefanie C. P. Lopes
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Gerência de Malária, Manaus, AM, Brazil
- Instituto Leônidas & Maria Deane, FIOCRUZ-AMAZONAS, Manaus, AM, Brazil
| | - Marcus V. G. Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Gerência de Malária, Manaus, AM, Brazil
- Instituto Leônidas & Maria Deane, FIOCRUZ-AMAZONAS, Manaus, AM, Brazil
| | - Ricardo L. D. Machado
- Centro de Investigação de Microrganismos, Universidade Federal Fluminense, RJ, Brazil
| | - Fabio T. M. Costa
- Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, SP, Brazil
| | - Letusa Albrecht
- Instituto Carlos Chagas, Fundação Oswaldo Cruz–FIOCRUZ. Curitiba, PR, Brazil
- * E-mail: ,
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16
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Salinas ND, Tang WK, Tolia NH. Blood-Stage Malaria Parasite Antigens: Structure, Function, and Vaccine Potential. J Mol Biol 2019; 431:4259-4280. [PMID: 31103771 DOI: 10.1016/j.jmb.2019.05.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/22/2019] [Accepted: 05/08/2019] [Indexed: 10/26/2022]
Abstract
Plasmodium parasites are the causative agent of malaria, a disease that kills approximately 450,000 individuals annually, with the majority of deaths occurring in children under the age of 5 years and the development of a malaria vaccine is a global health priority. Plasmodium parasites undergo a complex life cycle requiring numerous diverse protein families. The blood stage of parasite development results in the clinical manifestation of disease. A vaccine that disrupts the blood stage is highly desired and will aid in the control of malaria. The blood stage comprises multiple steps: invasion of, asexual growth within, and egress from red blood cells. This review focuses on blood-stage antigens with emphasis on antigen structure, antigen function, neutralizing antibodies, and vaccine potential.
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Affiliation(s)
- Nichole D Salinas
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD,, 20892, USA
| | - Wai Kwan Tang
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD,, 20892, USA
| | - Niraj H Tolia
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD,, 20892, USA.
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17
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Bittencourt NC, Leite JA, Silva ABIE, Pimenta TS, Silva-Filho JL, Cassiano GC, Lopes SCP, Dos-Santos JCK, Bourgard C, Nakaya HI, da Silva Ventura AMR, Lacerda MVG, Ferreira MU, Machado RLD, Albrecht L, Costa FTM. Genetic sequence characterization and naturally acquired immune response to Plasmodium vivax Rhoptry Neck Protein 2 (PvRON2). Malar J 2018; 17:401. [PMID: 30382855 PMCID: PMC6208078 DOI: 10.1186/s12936-018-2543-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 10/22/2018] [Indexed: 12/28/2022] Open
Abstract
Background The genetic diversity of malaria antigens often results in allele variant-specific immunity, imposing a great challenge to vaccine development. Rhoptry Neck Protein 2 (PvRON2) is a blood-stage antigen that plays a key role during the erythrocyte invasion of Plasmodium vivax. This study investigates the genetic diversity of PvRON2 and the naturally acquired immune response to P. vivax isolates. Results Here, the genetic diversity of PvRON21828–2080 and the naturally acquired humoral immune response against PvRON21828–2080 in infected and non-infected individuals from a vivax malaria endemic area in Brazil was reported. The diversity analysis of PvRON21828–2080 revealed that the protein is conserved in isolates in Brazil and worldwide. A total of 18 (19%) patients had IgG antibodies to PvRON21828–2080. Additionally, the analysis of the antibody response in individuals who were not acutely infected with malaria, but had been infected with malaria in the past indicated that 32 patients (33%) exhibited an IgG immune response against PvRON2. Conclusions PvRON2 was conserved among the studied isolates. The presence of naturally acquired antibodies to this protein in the absence of the disease suggests that PvRON2 induces a long-term antibody response. These results indicate that PvRON2 is a potential malaria vaccine candidate. Electronic supplementary material The online version of this article (10.1186/s12936-018-2543-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Najara C Bittencourt
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Juliana A Leite
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | | | - Tamirys S Pimenta
- Laboratório de Ensaios Clínicos e Imunogenética em Malária, Instituto Evandro Chagas/SVS/MS, Ananindeua, PA, Brazil
| | - João Luiz Silva-Filho
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Gustavo C Cassiano
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Stefanie C P Lopes
- Instituto Leônidas & Maria Deane, Fundação Oswaldo Cruz - FIOCRUZ, Manaus, AM, Brazil.,Fundação de Medicina Tropical-Dr. Heitor Vieira Dourado, Manaus, AM, Brazil
| | - Joao C K Dos-Santos
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Catarina Bourgard
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil
| | - Helder I Nakaya
- School of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | | | - Marcus V G Lacerda
- Instituto Leônidas & Maria Deane, Fundação Oswaldo Cruz - FIOCRUZ, Manaus, AM, Brazil.,Fundação de Medicina Tropical-Dr. Heitor Vieira Dourado, Manaus, AM, Brazil
| | - Marcelo U Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo-USP, São Paulo, Brazil
| | - Ricardo L D Machado
- Laboratório de Ensaios Clínicos e Imunogenética em Malária, Instituto Evandro Chagas/SVS/MS, Ananindeua, PA, Brazil
| | - Letusa Albrecht
- Instituto Carlos Chagas, Fundação Oswaldo Cruz - FIOCRUZ, Curitiba, PR, Brazil.
| | - Fabio T M Costa
- Laboratory of Tropical Diseases-Prof. Dr. Luiz Jacintho da Silva, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas-UNICAMP, Campinas, SP, Brazil.
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18
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Guy AJ, Irani V, Richards JS, Ramsland PA. Structural patterns of selection and diversity for Plasmodium vivax antigens DBP and AMA1. Malar J 2018; 17:183. [PMID: 29720179 PMCID: PMC5930944 DOI: 10.1186/s12936-018-2324-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/18/2018] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Plasmodium vivax is a significant contributor to the global malaria burden, and a vaccine targeting vivax malaria is urgently needed. An understanding of the targets of functional immune responses during the course of natural infection will aid in the development of a vaccine. Antibodies play a key role in this process, with responses against particular epitopes leading to immune selection pressure on these epitopes. A number of techniques exist to estimate levels of immune selection pressure on particular epitopes, with a sliding window analysis often used to determine particular regions likely to be under immune pressure. However, such analysis neglects protein three-dimensional structural information. With this in mind, a newly developed tool, BioStructMap, was applied to two key antigens from Plasmodium vivax: PvAMA1 and PvDBP Region II. This tool incorporates structural information into tests of selection pressure. RESULTS Sequences from a number of populations were analysed, examining spatially-derived nucleotide diversity and Tajima's D over protein structures for PvAMA1 and PvDBP. Structural patterns of nucleotide diversity were similar across all populations examined, with Domain I of PvAMA1 having the highest nucleotide diversity and displaying significant signatures of immune selection pressure (Tajima's D > 0). Nucleotide diversity for PvDBP was highest bordering the dimerization and DARC-binding interface, although there was less evidence of immune selection pressure on PvDBP compared with PvAMA1. This study supports previous work that has identified Domain I as the main target of immune-mediated selection pressure for PvAMA1, and also supports studies that have identified functional epitopes within PvDBP Region II. CONCLUSIONS The BioStructMap tool was applied to leading vaccine candidates from P. vivax, to examine structural patterns of selection and diversity across a number of geographic populations. There were striking similarities in structural patterns of diversity across multiple populations. Furthermore, whilst regions of high diversity tended to surround conserved binding interfaces, a number of protein regions with very low diversity were also identified, and these may be useful targets for further vaccine development, given previous evidence of functional antibody responses against these regions.
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Affiliation(s)
- Andrew J Guy
- Life Sciences, Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia.,Department of Immunology, Monash University, Melbourne, Australia
| | - Vashti Irani
- Life Sciences, Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia.,Department of Medicine, University of Melbourne, Melbourne, Australia
| | - Jack S Richards
- Life Sciences, Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia. .,Department of Medicine, University of Melbourne, Melbourne, Australia. .,Department of Infectious Diseases, Monash University, Melbourne, Australia. .,Victorian Infectious Diseases Service, Royal Melbourne Hospital, Melbourne, Australia.
| | - Paul A Ramsland
- Life Sciences, Burnet Institute, 85 Commercial Road, Melbourne, VIC, 3004, Australia. .,Department of Immunology, Monash University, Melbourne, Australia. .,School of Science, RMIT University, Plenty Road, Bundoora, VIC, 3083, Australia. .,Department of Surgery Austin Health, University of Melbourne, Heidelberg, Australia.
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19
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Kusi KA, Faber BW, Koopman G, Remarque EJ. EDiP: the Epitope Dilution Phenomenon. Lessons learnt from a malaria vaccine antigen and its applicability to polymorphic antigens. Expert Rev Vaccines 2017; 17:13-21. [PMID: 29224404 DOI: 10.1080/14760584.2018.1411198] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
INTRODUCTION Polymorphism in vaccine antigens poses major challenges to vaccinologists. The Plasmodium falciparum Apical Membrane Antigen 1 (AMA1) poses such a challenge. We found that immunization with a mixture of three variants yielded functional antibody levels to all variants comparable to levels induced by monovalent immunization. The mechanism behind the observed broadening was shown to be an increase in the fraction of cross-reactive antibodies, most likely because strain-specific epitopes are present at lower frequency relative to conserved epitopes. Areas covered: We hereby introduce the Epitope Dilution Phenomenon (EDiP) as a practical strategy for the induction of broad, cross-variant antibody responses against polymorphic antigens and discuss the utility and applicability of this phenomenon for the development of vaccines against polymorphic antigens of pathogens like Influenza, HIV, Dengue and Plasmodium. Expert commentary: EDiP can be used to broaden antibody responses by immunizing with a mixture of at least 3 antigenic variants, where the variants included can differ, yet yield broadened responses.
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Affiliation(s)
- Kwadwo Asamoah Kusi
- a Immunology Department , Noguchi Memorial Institute for Medical Research, College of Health Sciences University of Ghana , Accra , Ghana
| | - Bart W Faber
- b Department of Parasitology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
| | - Gerrit Koopman
- c Department of Virology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
| | - Edmond Joseph Remarque
- c Department of Virology , Biomedical Primate Research Centre , Rijswijk , The Netherlands
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20
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Mechanisms of naturally acquired immunity to P. falciparum and approaches to identify merozoite antigen targets. Parasitology 2017; 145:839-847. [PMID: 29144217 DOI: 10.1017/s0031182017001949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Malaria is one the most serious infectious diseases with over 200 million clinical cases annually. Most cases of the severe disease are caused by Plasmodium falciparum. The blood stage of Plasmodium parasite is entirely responsible for malaria-associated pathology. The population most susceptible to severe malaria are children under the age of 5, with low levels of immunity. It is only after many years of repeated exposure that individuals living in endemic areas develop clinical immunity. This form of protection prevents clinical episodes by substantially reducing parasite burden. Naturally acquired immunity predominantly targets blood-stage parasites with antibody responses being the main mediators of protection. The targets of clinical immunity are the extracellular merozoite and the infected erythrocyte surface, with the extremely diverse PfEMP1 proteins the main target here. This observation provides a strong rationale that an effective anti-malaria vaccine targeting blood-stage parasites is achievable. Thus the identification of antigenic targets of naturally acquired immunity remains an important step towards the formulation of novel vaccine combinations before testing their efficacy in clinical trials. This review summarizes the main findings to date defining antigenic targets present on the extracellular merozoite associated with naturally acquired immunity to P. falciparum malaria.
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21
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Nedaei F, Noormohammadi Z, Naddaf SR, Mohammadi S, Esmaeili Rastaghi AR. Analysis of Plasmodium vivax Apical Membrane Antigen-1 (PvAMA-1) Haplotypes among Iranian Isolates. INTERNATIONAL JOURNAL OF MOLECULAR AND CELLULAR MEDICINE 2017; 6:222-234. [PMID: 29988191 PMCID: PMC6004292 DOI: 10.22088/bums.6.4.222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 11/11/2017] [Indexed: 11/18/2022]
Abstract
Plasmodium vivax apical membrane antigen-1(PvAMA-1) is a surface protein with polymorphic sites. This study was aimed to analyze the polymorphic amino acid residues at PvAMA-1 in different infected age groups. 92 blood samples were collected from the south and southeast of Iran. The DNA coding for the domain I (DI), DII, and partial DIII of this antigen was amplified by Nested-PCR, and sequenced. Nucleotide mutations were found in 49 sites and based on the amino acid sequence, 30 variable sites were detected. Age distribution of malaria cases showed that the majority of the patients were between 10 to 30 years old. The scattering plot haplotypes by age showed an increasing incidence rate with age during childhood, whereas, incidence was the lowest in patients under five years old. Comparison of the polymorphic sites of PvAMA-1 in Iranian isolates with those found in other geographic regions of the world indicated nine common variable positions. In addition, a significant dependence was found between some particular substitutions and age categories. Dependence between particular substitutions and age groups suggests that certain residues in AMA-1 are responsible for clinical attacks in different ages, likely as a result of host immune pressure. The crystal structure of the PvAMA-1 showed that the amino acid substitutions that changed the protein charge were exclusively located in loops and turns where, the interactions with antibodies could occur. These data provide the necessary information for an AMA-1 based malaria vaccine design to be effective across all ages.
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Affiliation(s)
- Fatemeh Nedaei
- Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran
| | - Zahra Noormohammadi
- Department of Biology , College of Basic Science Islamic Azad University, Science and Research Branch, Tehran, Iran
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22
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Chew CH, Lim YAL, Chua KH. Heterologous expression of Plasmodium vivax apical membrane antigen 1 (PvAMA1) for binding peptide selection. PeerJ 2017; 5:e3794. [PMID: 28929019 PMCID: PMC5600724 DOI: 10.7717/peerj.3794] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/19/2017] [Indexed: 12/14/2022] Open
Abstract
Background Plasmodium is an obligate intracellular parasite. Apical membrane antigen 1 (AMA1) is the most prominent and well characterized malarial surface antigen that is essential for parasite-host cell invasion, i.e., for sporozoite to invade and replicate within hepatocytes in the liver stage and merozoite to penetrate and replicate within erythrocytes in the blood stage. AMA1 has long served as a potent antimalarial drug target and is a pivotal vaccine candidate. A good understanding of the structure and molecular function of this Plasmodium protein, particularly its involvement in host-cell adhesion and invasion, is of great interest and hence it offers an attractive target for the development of novel therapeutics. The present study aims to heterologous express recombinant Plasmodium AMA1 ectodomain of P. vivax (rPvAMA1) for the selection of binding peptides. Methods The rPvAMA1 protein was heterologous expressed using a tag-free Profinity eXactTM system and codon optimized BL21-Codon Plus (DE3)-RIL Escherichia coli strain and further refolded by dialysis for renaturation. Binding peptides toward refolded rPvAMA1 were panned using a Ph.D.-12 random phage display library. Results The rPvAMA1 was successfully expressed and refolded with three phage-displayed dodecapeptides designated as PdV1 (DLTFTVNPLSKA), PdV2 (WHWSWWNPNQLT), and PdV3 (TSVSYINNRHNL) with affinity towards rPvAMA1 identified. All of them exhibited positive binding signal to rPvAMA1 in both direct phage assays, i.e., phage ELISA binding assay and Western blot binding assay. Discussion Phage display technology enables the mapping of protein-protein interactions based on a simple principle that a library of phage particles displaying peptides is used and the phage clones that bind to the target protein are selected and identified. The binding sites of each selected peptides toward PvAMA1 (Protein Data Bank, PDB ID: 1W8K) were in silico predicted using CABS-dock web server. In this case, the binding peptides provide a valuable starting point for the development of peptidomimetic as antimalarial antagonists directed at PvAMA1.
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Affiliation(s)
- Ching Hoong Chew
- School of Biomedicine, Faculty of Health Sciences, Universiti Sultan Zainal Abidin, Kuala Nerus, Terengganu, Malaysia
| | - Yvonne Ai Lian Lim
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Kek Heng Chua
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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23
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Arévalo-Pinzón G, Bermúdez M, Hernández D, Curtidor H, Patarroyo MA. Plasmodium vivax ligand-receptor interaction: PvAMA-1 domain I contains the minimal regions for specific interaction with CD71+ reticulocytes. Sci Rep 2017; 7:9616. [PMID: 28855657 PMCID: PMC5577344 DOI: 10.1038/s41598-017-10025-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 08/02/2017] [Indexed: 12/18/2022] Open
Abstract
The malarial parasite’s invasion is complex, active and coordinated, involving many low and high affinity interactions with receptors on target cell membrane. Proteomics analysis has described around 40 proteins in P. vivax which could be involved in reticulocyte invasion; few have been studied with the aim of elucidating how many of them establish specific interactions with their respective host cells. Given the importance of knowing which of the parasite’s protein regions are functionally important for invasion, minimum regions mediating specific interaction between Plasmodium vivax apical membrane antigen 1 (PvAMA-1) and its host cell were here elucidated. The region covering PvAMA-1 domains I and II (PvAMA-DI-II) specifically bound to the CD71+ red blood cell subpopulation. A 20 residue-long region (81EVENAKYRIPAGRCPVFGKG100) located in domain I was capable of inhibiting PvAMA-DI-II recombinant protein binding to young reticulocytes (CD71+CD45−) and rosette formation. This conserved peptide specifically interacted with high affinity with reticulocytes (CD71+) through a neuraminidase- and chymotrypsin-treatment sensitive receptor. Such results showed that, despite AMA-1 having universal functions during late Plasmodium invasion stages, PvAMA-1 had reticulocyte-preferring binding regions, suggesting that P. vivax target cell selection is not just restricted to initial interactions but maintained throughout the erythrocyte invasion cycle, having important implications for designing a specific anti-P. vivax vaccine.
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Affiliation(s)
- Gabriela Arévalo-Pinzón
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,PhD Program in Biomedical and Biological Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia
| | - Maritza Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,MSc Program in Biological Sciences, Pontificia Universidad Javeriana, Carrera 7 # 40-62, Bogotá, Colombia
| | - Diana Hernández
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia
| | - Hernando Curtidor
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia.,School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 # 26-20, Bogotá, Colombia. .,School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 #, 63C-69, Bogotá, Colombia.
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24
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Vulliez-Le Normand B, Saul FA, Hoos S, Faber BW, Bentley GA. Cross-reactivity between apical membrane antgen 1 and rhoptry neck protein 2 in P. vivax and P. falciparum: A structural and binding study. PLoS One 2017; 12:e0183198. [PMID: 28817634 PMCID: PMC5560645 DOI: 10.1371/journal.pone.0183198] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/31/2017] [Indexed: 02/03/2023] Open
Abstract
Malaria, a disease endemic in many tropical and subtropical regions, is caused by infection of the erythrocyte by the apicomplexan parasite Plasmodium. Host-cell invasion is a complex process but two Plasmodium proteins, Apical Membrane Antigen 1 (AMA1) and the Rhoptry Neck protein complex (RON), play a key role. AMA1, present on the surface of the parasite, binds tightly to the RON2 component of the RON protein complex, which is inserted into the erythrocyte membrane during invasion. Blocking the AMA1-RON2 interaction with antibodies or peptides inhibits invasion, underlining its importance in the Plasmodium life cycle and as a target for therapeutic strategies. We describe the crystal structure of the complex formed between AMA1 from P. vivax (PvAMA1) and a peptide derived from the externally exposed region of P. vivax RON2 (PvRON2sp1), and of the heterocomplex formed between P. falciparum AMA1 (PfAMA1) and PvRON2sp1. Binding studies show that the affinity of PvRON2sp1 for PvAMA1 is weaker than that previously reported for the PfRON2sp1-PfAMA1 association. Moreover, while PvRON2sp1 shows strong cross-reactivity with PfAMA1, PfRON2sp1 displays no detectable interaction with PvAMA1. The structures show that the equivalent residues PvRON2-Thr2055 and PfRON2-Arg2041 largely account for this pattern of reactivity.
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Affiliation(s)
- Brigitte Vulliez-Le Normand
- Institut Pasteur, Unité de Microbiologie Structurale, Département de Biologie Structurale et Chimie, Centre National de la Recherche Scientifique, UMR 3528, Université Paris Diderot, Sorbonne Paris Cité, Microbiologie Structurale, Paris, France
| | - Frederick A. Saul
- Institut Pasteur, Plate-forme de Cristallographie, Département de Biologie Structurale et Chimie, Centre National de la Recherche Scientifique UMR 3528, Paris, France
| | - Sylviane Hoos
- Institut Pasteur, Plate-Forme de Biophysique Moléculaire, Département de Biologie Structurale et Chimie, Centre National de la Recherche Scientifique UMR 3528, Paris, France
| | - Bart W. Faber
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Graham A. Bentley
- Institut Pasteur, Unité d’Immunologie Structurale, Département de Biologie Structurale et Chimie, Centre National de la Recherche Scientifique, URA 2185, Paris, France
- * E-mail:
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25
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Flores-Alanis A, González-Cerón L, Santillán F, Ximenez C, Sandoval MA, Cerritos R. Temporal genetic changes in Plasmodium vivax apical membrane antigen 1 over 19 years of transmission in southern Mexico. Parasit Vectors 2017; 10:217. [PMID: 28464959 PMCID: PMC5414334 DOI: 10.1186/s13071-017-2156-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2016] [Accepted: 04/25/2017] [Indexed: 01/21/2023] Open
Abstract
Background Mexico advanced to the pre-elimination phase in 2009 due to a significant reduction in malaria cases, and since 2000, Plasmodium vivax is the only species transmitted. During the last two decades, malaria transmission has been mostly local and isolated to a few regions. It is important to gain further insights into the impact of control measures on the parasite population structure. Hence, the aim of the current study was to determine detailed changes in P. vivax genetic diversity and population structure based on analysing the gene that encodes the apical membrane antigen 1 (pvama1). This analysis covered from control to pre-elimination (1993–2011) in a hypo-endemic region in southern Mexico. Results The 213 pvama1I-II sequences presently analysed were grouped into six periods of three years each. They showed low genetic diversity, with 15 haplotypes resolved. Among the DNA sequences, there was a gradual decrease in genetic diversity, the number of mixed genotype infections and the intensity of positive selection, in agreement with the parallel decline in malaria cases. At the same time, linkage disequilibrium (R2) increased. The three-dimensional haplotype network revealed that pvama1I-II haplotypes were separated by 1–11 mutational steps, and between one another by 0–3 unsampled haplotypes. In the temporal network, seven haplotypes were detected in at least two of the six-time layers, and only four distinct haplotypes were evidenced in the pre-elimination phase. Structure analysis indicated that three subpopulations fluctuated over time. Only 8.5% of the samples had mixed ancestry. In the pre-elimination phase, subpopulation P1 was drastically reduced, and the admixture was absent. Conclusions The results suggest that P. vivax in southern Mexico evolved based on local adaptation into three “pseudoclonal” subpopulations that diversified at the regional level and persisted over time, although with varying frequency. Control measures and climate events influenced the number of malaria cases and the genetic structure. The sharp decrease in parasite diversity and other related genetic parameters during the pre-elimination phase suggests that malaria elimination is possible in the near future. These results are useful for epidemiological surveillance. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2156-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alejandro Flores-Alanis
- División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, 04510, Mexico
| | - Lilia González-Cerón
- Centro Regional de Investigación en Salud Pública, Instituto Nacional de Salud Pública, Tapachula, Chiapas, 30700, Mexico.
| | - Frida Santillán
- Centro Regional de Investigación en Salud Pública, Instituto Nacional de Salud Pública, Tapachula, Chiapas, 30700, Mexico
| | - Cecilia Ximenez
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, 06729, Mexico
| | - Marco A Sandoval
- Centro Regional de Investigación en Salud Pública, Instituto Nacional de Salud Pública, Tapachula, Chiapas, 30700, Mexico
| | - René Cerritos
- División de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, 04510, Mexico.
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26
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In-silico screening, identification and validation of a novel vaccine candidate in the fight against Plasmodium falciparum. Parasitol Res 2017; 116:1293-1305. [DOI: 10.1007/s00436-017-5408-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/08/2017] [Indexed: 12/14/2022]
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27
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Patarroyo ME, Alba MP, Rojas-Luna R, Bermudez A, Aza-Conde J. Functionally relevant proteins in Plasmodium falciparum host cell invasion. Immunotherapy 2017; 9:131-155. [DOI: 10.2217/imt-2016-0091] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A totally effective, antimalarial vaccine must involve sporozoite and merozoite proteins (or their fragments) to ensure complete parasite blocking during critical invasion stages. This Special Report examines proteins involved in critical biological functions for parasite survival and highlights the conserved amino acid sequences of the most important proteins involved in sporozoite invasion of hepatocytes and merozoite invasion of red blood cells. Conserved high activity binding peptides are located in such proteins’ functionally strategic sites, whose functions are related to receptor binding, nutrient and protein transport, enzyme activity and molecule–molecule interactions. They are thus excellent targets for vaccine development as they block proteins binding function involved in invasion and also their biological function.
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Affiliation(s)
- Manuel E Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26–20 Bogotá, Colombia
- Universidad Nacional de Colombia, Bogotá DC, Colombia
| | - Martha P Alba
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26–20 Bogotá, Colombia
- Universidad de Ciencias Aplicadas y Ambientales (UDCA), Bogotá, Colombia
| | - Rocío Rojas-Luna
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26–20 Bogotá, Colombia
| | - Adriana Bermudez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26–20 Bogotá, Colombia
- Universidad del Rosario, Bogotá DC, Colombia
| | - Jorge Aza-Conde
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No. 26–20 Bogotá, Colombia
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28
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Maskus DJ, Królik M, Bethke S, Spiegel H, Kapelski S, Seidel M, Addai-Mensah O, Reimann A, Klockenbring T, Barth S, Fischer R, Fendel R. Characterization of a novel inhibitory human monoclonal antibody directed against Plasmodium falciparum Apical Membrane Antigen 1. Sci Rep 2016; 6:39462. [PMID: 28000709 PMCID: PMC5175200 DOI: 10.1038/srep39462] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/22/2016] [Indexed: 01/07/2023] Open
Abstract
Malaria remains a major challenge to global health causing extensive morbidity and mortality. Yet, there is no efficient vaccine and the immune response remains incompletely understood. Apical Membrane Antigen 1 (AMA1), a leading vaccine candidate, plays a key role during merozoite invasion into erythrocytes by interacting with Rhoptry Neck Protein 2 (RON2). We generated a human anti-AMA1-antibody (humAbAMA1) by EBV-transformation of sorted B-lymphocytes from a Ghanaian donor and subsequent rescue of antibody variable regions. The antibody was expressed in Nicotiana benthamiana and in HEK239-6E, characterized for binding specificity and epitope, and analyzed for its inhibitory effect on Plasmodium falciparum. The generated humAbAMA1 shows an affinity of 106-135 pM. It inhibits the parasite strain 3D7A growth in vitro with an expression system-independent IC50-value of 35 μg/ml (95% confidence interval: 33 μg/ml-37 μg/ml), which is three to eight times lower than the IC50-values of inhibitory antibodies 4G2 and 1F9. The epitope was mapped to the close proximity of the RON2-peptide binding groove. Competition for binding between the RON2-peptide and humAbAMA1 was confirmed by surface plasmon resonance spectroscopy measurements. The particularly advantageous inhibitory activity of this fully human antibody might provide a basis for future therapeutic applications.
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Affiliation(s)
- Dominika J. Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Michał Królik
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, KNUST, Kumasi, Ghana
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany
- Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Department of Experimental Medicine and Immunotherapy, Aachen, Germany
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29
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Molecular cloning, characterization and antigenicity ofBabesiasp. BQ1 (Lintan) (Babesiacf.motasi) apical membrane antigen-1 (AMA-1). Parasitology 2016; 144:641-649. [DOI: 10.1017/s0031182016002304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYApical membrane antigen-1 (AMA-1) has been described as a potential vaccine candidate in apicomplexan parasites. Here we characterize theama-1gene. The full-lengthama-1gene ofBabesiasp. BQ1 (Lintan) (BLTAMA-1) is 1785 bp, which contains an open reading frame (ORF) encoding a 65-kDa protein of 594 amino acid residues; by definition, the 5′ UTR precedes the first methionine of the ORF. Phylogenetic analysis based on AMA-1 amino acid sequences clearly separated Piroplasmida from other Apicomplexa parasites. TheBabesiasp. BQ1 (Lintan) AMA-1 sequence is most closely associated with that ofB. ovataandB. bigemina, with high bootstrap value. A recombinant protein encoding a conserved region and containing ectodomains I and II of BLTAMA-1 was constructed. BLTrAMA-1-DI/DII proteins were tested for reactivity with sera from sheep infected byBabesiasp. BQ1 (Lintan). In Western-blot analysis, nativeBabesiasp. BQ1 (Lintan) AMA-1 proteins were recognized by antibodies raised in rabbits against BLTrAMA-1in vitro. The results of this study are discussed in terms of gene characterization, taxonomy and antigenicity.
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Zhu X, Zhao P, Wang S, Liu F, Liu J, Wang J, Yang Z, Yan G, Fan Q, Cao Y, Cui L. Analysis of Pvama1 genes from China-Myanmar border reveals little regional genetic differentiation of Plasmodium vivax populations. Parasit Vectors 2016; 9:614. [PMID: 27899135 PMCID: PMC5129220 DOI: 10.1186/s13071-016-1899-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 11/21/2016] [Indexed: 12/22/2022] Open
Abstract
Background With the premise of diminishing parasite genetic diversity following the reduction of malaria incidence, the analysis of polymorphic antigenic markers may provide important information about the impact of malaria control on local parasite populations. Here we evaluated the genetic diversity of Plasmodium vivax apical membrane antigen 1 (Pvama1) gene in a parasite population from the China-Myanmar border and compared it with global P. vivax populations. Methods We performed evolutionary analysis to examine the genetic diversity, natural selection, and population differentiation of 73 Pvama1 sequences acquired from the China-Myanmar border as well as 615 publically available Pvama1 sequences from seven global P. vivax populations. Results A total of 308 Pvama1 haplotypes were identified among the global P. vivax isolates. The overall nucleotide diversity of Pvama1 gene among the 73 China-Myanmar border parasite isolates was 0.008 with 41 haplotypes being identified (Hd = 0.958). Domain I (DI) harbored the majority (26/33) of the polymorphic sites. The McDonald Kreitman test showed a significant positive selection across the ectodomain and the DI of Pvama1. The fixation index (FST) estimation between the China-Myanmar border, Thailand (0.01) and Myanmar (0.10) showed only slight geographical genetic differentiation. Notably, the Sal-I haplotype was not detected in any of the analyzed global isolates, whereas the Belem strain was restricted to the Thai population. The detected mutations are mapped outside the overlapped region of the predicted B-cell epitopes and intrinsically unstructured/disordered regions. Conclusions This study revealed high levels of genetic diversity of Pvama1 in the P. vivax parasite population from the China-Myanmar border with DI displaying stronger diversifying selection than other domains. There were low levels of population subdivision among parasite populations from the Greater Mekong Subregion. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1899-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiaotong Zhu
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, 110122, China
| | - Pan Zhao
- Department of Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Si Wang
- Department of Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Fei Liu
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, 110122, China
| | - Jun Liu
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, 110122, China
| | - Jian Wang
- Department of Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, Liaoning, 110122, China
| | - Zhaoqing Yang
- Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA, USA
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, 110122, China.
| | - Liwang Cui
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning, 110122, China. .,Department of Entomology, The Pennsylvania State University, University Park, PA, 16802, USA.
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Addai-Mensah O, Seidel M, Amidu N, Maskus DJ, Kapelski S, Breuer G, Franken C, Owusu-Dabo E, Frempong M, Rakotozandrindrainy R, Schinkel H, Reimann A, Klockenbring T, Barth S, Fischer R, Fendel R. Acquired immune responses to three malaria vaccine candidates and their relationship to invasion inhibition in two populations naturally exposed to malaria. Malar J 2016; 15:65. [PMID: 26850066 PMCID: PMC4743426 DOI: 10.1186/s12936-016-1112-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2015] [Accepted: 01/19/2016] [Indexed: 11/10/2022] Open
Abstract
Background Malaria still represents a major cause of morbidity and mortality predominantly in several developing countries, and remains a priority in many public health programmes. Despite the enormous gains made in control and prevention the development of an effective vaccine represents a persisting challenge. Although several parasite antigens including pre-erythrocytic antigens and blood stage antigens have been thoroughly investigated, the identification of solid immune correlates of protection against infection by Plasmodium falciparum or clinical malaria remains a major hurdle. In this study, an immuno-epidemiological survey was carried out between two populations naturally exposed to P. falciparum malaria to determine the immune correlates of protection. Methods Plasma samples of immune adults from two countries (Ghana and Madagascar) were tested for their reactivity against the merozoite surface proteins MSP1-19, MSP3 and AMA1 by ELISA. The antigens had been selected on the basis of cumulative evidence of their role in anti-malarial immunity. Additionally, reactivity against crude P. falciparum lysate was investigated. Purified IgG from these samples were furthermore tested in an invasion inhibition assay for their antiparasitic activity. Results Significant intra- and inter- population variation of the reactivity of the samples to the tested antigens were found, as well as a significant positive correlation between MSP1-19 reactivity and invasion inhibition (p < 0.05). Interestingly, male donors showed a significantly higher antibody response to all tested antigens than their female counterparts. In vitro invasion inhibition assays comparing the purified antibodies from the donors from Ghana and Madagascar did not show any statistically significant difference. Although in vitro invasion inhibition increased with breadth of antibody response, the increase was not statistically significant. Conclusions The findings support the fact that the development of semi-immunity to malaria is probably contingent on the development of antibodies to not only one, but a range of antigens and that invasion inhibition in immune adults may be a function of antibodies to various antigens. This supports strategies of vaccination including multicomponent vaccines as well as passive vaccination strategies with antibody cocktails.
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Affiliation(s)
- Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany. .,RWTH Aachen University, Institute for Molecular Biotechnology, Worringerweg 1, 52074, Aachen, Germany. .,Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Nafiu Amidu
- Department of Biomedical Laboratory Science, School of Medicine and Health Science, University for Development Studies, Tamale, Ghana.
| | - Dominika J Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Gudrun Breuer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Carmen Franken
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Ellis Owusu-Dabo
- Kumasi Centre for Collaborative Research, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Margaret Frempong
- Department of Molecular Medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Raphaël Rakotozandrindrainy
- Laboratoire de Microbiologie et de Parasitologie, ESSAGRO-Faculté de Médecine, Université d'Antananarivo, Antananarivo, Madagascar.
| | - Helga Schinkel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany.
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany. .,Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Pauwelsstraße 20, 52074, Aachen, Germany. .,South African Research Chair in Cancer Biotechnology, Institute of Infectious Disease and Molecular Medicine (IDM), Department of Integrative Biomedical Sciences, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, 7925, South Africa.
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany. .,RWTH Aachen University, Institute for Molecular Biotechnology, Worringerweg 1, 52074, Aachen, Germany.
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstraße 6, 52074, Aachen, Germany. .,RWTH Aachen University, Institute for Molecular Biotechnology, Worringerweg 1, 52074, Aachen, Germany. .,Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Pauwelsstraße 20, 52074, Aachen, Germany.
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Rodrigues-da-Silva RN, Martins da Silva JH, Singh B, Jiang J, Meyer EVS, Santos F, Banic DM, Moreno A, Galinski MR, Oliveira-Ferreira J, Lima-Junior JDC. In silico Identification and Validation of a Linear and Naturally Immunogenic B-Cell Epitope of the Plasmodium vivax Malaria Vaccine Candidate Merozoite Surface Protein-9. PLoS One 2016; 11:e0146951. [PMID: 26788998 PMCID: PMC4720479 DOI: 10.1371/journal.pone.0146951] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 12/22/2015] [Indexed: 12/21/2022] Open
Abstract
Synthetic peptide vaccines provide the advantages of safety, stability and low cost. The success of this approach is highly dependent on efficient epitope identification and synthetic strategies for efficacious delivery. In malaria, the Merozoite Surface Protein-9 of Plasmodium vivax (PvMSP9) has been considered a vaccine candidate based on the evidence that specific antibodies were able to inhibit merozoite invasion and recombinant proteins were highly immunogenic in mice and humans. However the identities of linear B-cell epitopes within PvMSP9 as targets of functional antibodies remain undefined. We used several publicly-available algorithms for in silico analyses and prediction of relevant B cell epitopes within PMSP9. We show that the tandem repeat sequence EAAPENAEPVHENA (PvMSP9E795-A808) present at the C-terminal region is a promising target for antibodies, given its high combined score to be a linear epitope and located in a putative intrinsically unstructured region of the native protein. To confirm the predictive value of the computational approach, plasma samples from 545 naturally exposed individuals were screened for IgG reactivity against the recombinant PvMSP9-RIRII729-972 and a synthetic peptide representing the predicted B cell epitope PvMSP9E795-A808. 316 individuals (58%) were responders to the full repetitive region PvMSP9-RIRII, of which 177 (56%) also presented total IgG reactivity against the synthetic peptide, confirming it validity as a B cell epitope. The reactivity indexes of anti-PvMSP9-RIRII and anti-PvMSP9E795-A808 antibodies were correlated. Interestingly, a potential role in the acquisition of protective immunity was associated with the linear epitope, since the IgG1 subclass against PvMSP9E795-A808 was the prevalent subclass and this directly correlated with time elapsed since the last malaria episode; however this was not observed in the antibody responses against the full PvMSP9-RIRII. In conclusion, our findings identified and experimentally confirmed the potential of PvMSP9E795-A808 as an immunogenic linear B cell epitope within the P. vivax malaria vaccine candidate PvMSP9 and support its inclusion in future subunit vaccines.
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Affiliation(s)
| | | | - Balwan Singh
- Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Jianlin Jiang
- Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Esmeralda V. S. Meyer
- Environmental Health and Safety Office, Emory University, Atlanta, GA, United States of America
| | - Fátima Santos
- National Health Foundation, Department of Entomology, Central Laboratory, Porto Velho, RO, Brazil
| | - Dalma Maria Banic
- Laboratory of Simulids and Onchocerciasis "Malaria and Onchocerciasis Research", Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
| | - Alberto Moreno
- Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Emory University, Atlanta, GA, United States of America
| | - Mary R. Galinski
- Emory Vaccine Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Emory University, Atlanta, GA, United States of America
| | - Joseli Oliveira-Ferreira
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ, Brazil
- * E-mail: (JCLJ); (JO-F)
| | - Josué da Costa Lima-Junior
- Laboratório de Imunoparasitologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (FIOCRUZ), Rio de Janeiro, RJ, Brazil
- * E-mail: (JCLJ); (JO-F)
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Delgadillo RF, Parker ML, Lebrun M, Boulanger MJ, Douguet D. Stability of the Plasmodium falciparum AMA1-RON2 Complex Is Governed by the Domain II (DII) Loop. PLoS One 2016; 11:e0144764. [PMID: 26731670 PMCID: PMC4701444 DOI: 10.1371/journal.pone.0144764] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/22/2015] [Indexed: 12/20/2022] Open
Abstract
Plasmodium falciparum is an obligate intracellular protozoan parasite that employs a highly sophisticated mechanism to access the protective environment of the host cells. Key to this mechanism is the formation of an electron dense ring at the parasite-host cell interface called the Moving Junction (MJ) through which the parasite invades. The MJ incorporates two key parasite components: the surface protein Apical Membrane Antigen 1 (AMA1) and its receptor, the Rhoptry Neck Protein (RON) complex, the latter one being targeted to the host cell membrane during invasion. Crystal structures of AMA1 have shown that a partially mobile loop, termed the DII loop, forms part of a deep groove in domain I and overlaps with the RON2 binding site. To investigate the mechanism by which the DII loop influences RON2 binding, we measured the kinetics of association and dissociation and binding equilibria of a PfRON2sp1 peptide with both PfAMA1 and an engineered form of PfAMA1 where the flexible region of the DII loop was replaced by a short Gly-Ser linker (ΔDII-PfAMA1). The reactions were tracked by fluorescence anisotropy as a function of temperature and concentration and globally fitted to acquire the rate constants and corresponding thermodynamic profiles. Our results indicate that both PfAMA1 constructs bound to the PfRON2sp1 peptide with the formation of one intermediate in a sequential reversible reaction: A↔B↔C. Consistent with Isothermal Titration Calorimetry measurements, final complex formation was enthalpically driven and slightly entropically unfavorable. Importantly, our experimental data shows that the DII loop lengthened the complex half-life time by 18-fold (900 s and 48 s at 25°C for Pf and ΔDII-Pf complex, respectively). The longer half-life of the Pf complex appeared to be driven by a slower dissociation process. These data highlight a new influential role for the DII loop in kinetically locking the functional binary complex to enable host cell invasion.
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Affiliation(s)
- Roberto F. Delgadillo
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
| | - Michelle L. Parker
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Maryse Lebrun
- UMR 5235 CNRS, Université de Montpellier, 34095, Montpellier, France
| | - Martin J. Boulanger
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Dominique Douguet
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
- * E-mail:
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González-Cerón L, Cerritos R, Corzo-Mancilla J, Santillán F. Diversity and evolutionary genetics of the three major Plasmodium vivax merozoite genes participating in reticulocyte invasion in southern Mexico. Parasit Vectors 2015; 8:651. [PMID: 26691669 PMCID: PMC4687067 DOI: 10.1186/s13071-015-1266-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/11/2015] [Indexed: 11/25/2022] Open
Abstract
Background Reported malaria cases in the Americas had been reduced to about one-half million by 2012. To advance towards elimination of this disease, it is necessary to gain insights into how the malaria parasite is evolving, including the emergence, spread and persistence of new haplotypes in affected regions. In here, the genetic diversity of the three major P. vivax merozoite genes was analyzed. Methods From P. vivax-infected blood samples obtained in southern Mexico (SMX) during 2006–2007, nucleotide sequences were achieved for: the 42 kDa carboxyl fragment of the merozoite surface protein-1 (msp142), domains I-II of the apical membrane antigen-1 (ama1I-II), and domain II of the Duffy binding protein (dbpII). Gene polymorphism was examined and haplotype networks were developed to depict parasite relationships in SMX. Then genetic diversity, recombination and natural selection were analyzed and the degree of differentiation was determined as FST values. Results The diversity of P. vivax merozoite genes in SMX was less than that of parasites from other geographic origins, with dbpII < ama1I-II < msp142. Ama1I-II and msp142 exposed the more numerous haplotypes exclusive to SMX. While, all dbpII haplotypes from SMX were separated from one to three mutational steps, the networks of ama1I-II and msp142 were more complex; loops and numerous mutational steps were evidenced, likely due to recombination. Sings of local diversification were more evident for msp142. Sixteen combined haplotypes were determined; one of these haplotypes not detected in 2006 was highly frequent in 2007. The Rm value was higher for msp142than for ama1I-II, being insignificant for dbpII. The dN-dS value was highly significant for ama1I-II and lesser so for dbpII. The FST values were higher for dbpII than msp142, and very low for ama1I-II. Conclusions In SMX, P. vivax ama1I-II, dbpII and msp142 demonstrated limited diversity, and exhibited a differentiated parasite population. The results suggest that differential intensities of selective forces are operating on these gene fragments, and probably related to their timing, length of exposure and function during reticulocyte adhesion and invasion. Therefore, these finding are essential for mono and multivalent vaccine development and for epidemiological surveillance. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1266-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lilia González-Cerón
- Regional Centre for Research in Public Health, National Institute for Public Health, Tapachula, Chiapas, 30700, Mexico.
| | - Rene Cerritos
- Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, 04510, México.
| | - Jordán Corzo-Mancilla
- Regional Centre for Research in Public Health, National Institute for Public Health, Tapachula, Chiapas, 30700, Mexico.
| | - Frida Santillán
- Regional Centre for Research in Public Health, National Institute for Public Health, Tapachula, Chiapas, 30700, Mexico.
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Abstract
A safe and effective malaria vaccine is a crucial part of the roadmap to malaria elimination/eradication by the year 2050. Viral-vectored vaccines based on adenoviruses and modified vaccinia virus Ankara (MVA) expressing malaria immunogens are currently being used in heterologous prime-boost regimes in clinical trials for induction of strong antigen-specific T-cell responses and high-titer antibodies. Recombinant MVA is a safe and well-tolerated attenuated vector that has consistently shown significant boosting potential. Advances have been made in large-scale MVA manufacture as high-yield producer cell lines and high-throughput purification processes have recently been developed. This review describes the use of MVA as malaria vaccine vector in both preclinical and clinical studies in the past 5 years.
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Salavatifar M, Zakeri S, Hayati Roodbari N, Djadid ND. High-Level Expression, Purification and Characterization of A Recombinant Plasmodium vivax Apical Membrane Antigen 1: Implication for vivax Malaria Vaccine Development. CELL JOURNAL 2015; 17:520-31. [PMID: 26464824 PMCID: PMC4601873 DOI: 10.22074/cellj.2015.12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Accepted: 08/06/2014] [Indexed: 12/22/2022]
Abstract
Objective The apical membrane antigen-1 (AMA-1) is considered as a promising candidate for development of a malaria vaccine against Plasmodium parasites. The correct
conformation of this protein appears to be necessary for the stimulation of parasite-inhibitory responses, and these responses, in turn, seem to be antibody-mediated. Therefore, in
the present investigation, we expressed the Plasmodium vivax AMA-1 (PvAMA-1) ectodomain in Escherichia coli (E. coli), purified it using standard procedures and characterized
it to determine its biological activities for it to be used as a potential target for developing
a protective and safe vivax malaria vaccine.
Materials and Methods In this experimental investigation, the ectodomain of PvAMA-1 antigen (GenBank accession no. JX624741) was expressed in the E. coli M15pQE30 expression system and purified with immobilized-metal affinity chromatography. The correct conformation of the recombinant protein was evaluated by Western
blotting and indirect immunofluorescence antibody (IFA) test. In addition, the immunogenic properties of PvAMA-1 were evaluated in BALB/c mice with the purified protein
emulsified in Freund’s adjuvant.
Results In the present study, the PvAMA-1 ectodomain was expressed at a high-level
(65 mg/L) using a bacterial system. Reduced and non-reduced sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) as well as Western blot analysis
confirmed the appropriate conformation and folding of PvAMA-1. The evaluation of
immunogenic properties of PvAMA-1 showed that both T helper-1 and 2 cells (Th1
and Th2) responses were present in mice after three immunizations and persisted up
to one year after the first immunization. Moreover, the antibodies raised against the
recombinant PvAMA-1 in injected mice could recognize the native protein localized on
P. vivax parasites.
Conclusion We demonstrate that our recombinant protein had proper conformation
and folding. Also, there were common epitopes in the recombinant forms corresponding to native proteins. These results; therefore, indicate that the expressed PvAMA-1
has the potential to be used as a vivax malaria vaccine.
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Affiliation(s)
- Maryam Salavatifar
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Sedigheh Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BCR), Pasteur Institute of Iran, Tehran, Iran
| | - Nasim Hayati Roodbari
- Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Navid Dinparast Djadid
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BCR), Pasteur Institute of Iran, Tehran, Iran
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Expression, Purification, and Biological Characterization of Babesia microti Apical Membrane Antigen 1. Infect Immun 2015. [PMID: 26195550 DOI: 10.1128/iai.00168-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The intraerythrocytic apicomplexan Babesia microti, the primary causative agent of human babesiosis, is a major public health concern in the United States and elsewhere. Apicomplexans utilize a multiprotein complex that includes a type I membrane protein called apical membrane antigen 1 (AMA1) to invade host cells. We have isolated the full-length B. microti AMA1 (BmAMA1) gene and determined its nucleotide sequence, as well as the amino acid sequence of the AMA1 protein. This protein contains an N-terminal signal sequence, an extracellular region, a transmembrane region, and a short conserved cytoplasmic tail. It shows the same domain organization as the AMA1 orthologs from piroplasm, coccidian, and haemosporidian apicomplexans but differs from all other currently known piroplasmida, including other Babesia and Theileria species, in lacking two conserved cysteines in highly variable domain III of the extracellular region. Minimal polymorphism was detected in BmAMA1 gene sequences of parasite isolates from six babesiosis patients from Nantucket. Immunofluorescence microscopy studies showed that BmAMA1 is localized on the cell surface and cytoplasm near the apical end of the parasite. Native BmAMA1 from parasite lysate and refolded recombinant BmAMA1 (rBmAMA1) expressed in Escherichia coli reacted with a mouse anti-BmAMA1 antibody using Western blotting. In vitro binding studies showed that both native BmAMA1 and rBmAMA1 bind to human red blood cells (RBCs). This binding is trypsin and chymotrypsin treatment sensitive but neuraminidase independent. Incubation of B. microti parasites in human RBCs with a mouse anti-BmAMA1 antibody inhibited parasite growth by 80% in a 24-h assay. Based on its antigenically conserved nature and potential role in RBC invasion, BmAMA1 should be evaluated as a vaccine candidate.
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Crossey E, Frietze K, Narum DL, Peabody DS, Chackerian B. Identification of an Immunogenic Mimic of a Conserved Epitope on the Plasmodium falciparum Blood Stage Antigen AMA1 Using Virus-Like Particle (VLP) Peptide Display. PLoS One 2015; 10:e0132560. [PMID: 26147502 PMCID: PMC4493041 DOI: 10.1371/journal.pone.0132560] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 06/16/2015] [Indexed: 12/22/2022] Open
Abstract
We have developed a peptide display platform based on VLPs of the RNA bacteriophage MS2 that combines the high immunogenicity of VLP display with affinity selection capabilities. Random peptides can be displayed on the VLP surface by genetically inserting sequences into a surface-exposed loop of the viral coat protein. VLP-displayed peptides can then be isolated by selection using antibodies, and the VLP selectants can then be used directly as immunogens. Here, we investigated the ability of this platform to identify mimotopes of a highly conserved conformational epitope present on the Plasmodium falciparum blood-stage protein AMA1. Using 4G2, a monoclonal antibody that binds to this epitope and is a potent inhibitor of erythrocyte invasion, we screened three different VLP-peptide libraries and identified specific VLPs that bound strongly to the selecting mAb. We then tested the ability of a handful of selected VLPs to elicit anti-AMA1 antibody responses in mice. Most of the selected VLPs failed to reliably elicit AMA1 specific antibodies. However, one VLP consistently induced antibodies that cross-reacted with AMA1. Surprisingly, this VLP bound to 4G2 more weakly than the other selectants we identified. Taken together, these data demonstrate that VLP-peptide display can identify immunogenic mimics of a complex conformational epitope and illustrate the promise and challenges of this approach.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Protozoan/immunology
- Antibody Affinity
- Antigen-Antibody Reactions
- Antigens, Protozoan/chemistry
- Antigens, Protozoan/immunology
- Antigens, Surface/chemistry
- Antigens, Surface/immunology
- Chromatography, Gel
- Cross Reactions
- Dimerization
- Enzyme-Linked Immunosorbent Assay
- Epitopes/chemistry
- Epitopes/immunology
- Levivirus
- Malaria Vaccines/immunology
- Membrane Proteins/chemistry
- Membrane Proteins/immunology
- Mice
- Mice, Inbred BALB C
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Peptide Library
- Peptides/chemistry
- Peptides/immunology
- Plasmodium falciparum/immunology
- Protein Conformation
- Protozoan Proteins/chemistry
- Protozoan Proteins/immunology
- Sequence Analysis, Protein
- Vaccines, Virus-Like Particle/immunology
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Affiliation(s)
- Erin Crossey
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America
| | - Kathryn Frietze
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America
| | - David L. Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, United States of America
| | - David S. Peabody
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America
| | - Bryce Chackerian
- Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, United States of America
- * E-mail:
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Parker ML, Boulanger MJ. An Extended Surface Loop on Toxoplasma gondii Apical Membrane Antigen 1 (AMA1) Governs Ligand Binding Selectivity. PLoS One 2015; 10:e0126206. [PMID: 25955165 PMCID: PMC4425356 DOI: 10.1371/journal.pone.0126206] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 03/31/2015] [Indexed: 11/18/2022] Open
Abstract
Apicomplexan parasites are the causative agents of globally prevalent diseases including malaria and toxoplasmosis. These obligate intracellular pathogens have evolved a sophisticated host cell invasion strategy that relies on a parasite-host cell junction anchored by interactions between apical membrane antigens (AMAs) on the parasite surface and rhoptry neck 2 (RON2) proteins discharged from the parasite and embedded in the host cell membrane. Key to formation of the AMA1-RON2 complex is displacement of an extended surface loop on AMA1 called the DII loop. While conformational flexibility of the DII loop is required to expose the mature RON2 binding groove, a definitive role of this substructure has not been elucidated. To establish a role of the DII loop in Toxoplasma gondii AMA1, we engineered a form of the protein where the mobile portion of the loop was replaced with a short Gly-Ser linker (TgAMA1ΔDIIloop). Isothermal titration calorimetry measurements with a panel of RON2 peptides revealed an influential role for the DII loop in governing selectivity. Most notably, an Eimeria tenella RON2 (EtRON2) peptide that showed only weak binding to TgAMA1 bound with high affinity to TgAMA1ΔDIIloop. To define the molecular basis for the differential binding, we determined the crystal structure of TgAMA1ΔDIIloop in complex with the EtRON2 peptide. When analyzed in the context of existing AMA1-RON2 structures, spatially distinct anchor points in the AMA1 groove were identified that, when engaged, appear to provide the necessary traction to outcompete the DII loop. Collectively, these data support a model where the AMA1 DII loop serves as a structural gatekeeper to selectively filter out ligands otherwise capable of binding with high affinity in the AMA1 apical groove. These data also highlight the importance of considering the functional implications of the DII loop in the ongoing development of therapeutic intervention strategies targeting the AMA1-RON2 invasion complex.
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Affiliation(s)
- Michelle L. Parker
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
| | - Martin J. Boulanger
- Department of Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
- * E-mail:
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40
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Boucher LE, Bosch J. The apicomplexan glideosome and adhesins - Structures and function. J Struct Biol 2015; 190:93-114. [PMID: 25764948 PMCID: PMC4417069 DOI: 10.1016/j.jsb.2015.02.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2014] [Revised: 02/20/2015] [Accepted: 02/26/2015] [Indexed: 01/10/2023]
Abstract
The apicomplexan family of pathogens, which includes Plasmodium spp. and Toxoplasma gondii, are primarily obligate intracellular parasites and invade multiple cell types. These parasites express extracellular membrane protein receptors, adhesins, to form specific pathogen-host cell interaction complexes. Various adhesins are used to invade a variety of cell types. The receptors are linked to an actomyosin motor, which is part of a complex comprised of many proteins known as the invasion machinery or glideosome. To date, reviews on invasion have focused primarily on the molecular pathways and signals of invasion, with little or no structural information presented. Over 75 structures of parasite receptors and glideosome proteins have been deposited with the Protein Data Bank. These structures include adhesins, motor proteins, bridging proteins, inner membrane complex and cytoskeletal proteins, as well as co-crystal structures with peptides and antibodies. These structures provide information regarding key interactions necessary for target receptor engagement, machinery complex formation, how force is transmitted, and the basis of inhibitory antibodies. Additionally, these structures can provide starting points for the development of antibodies and inhibitory molecules targeting protein-protein interactions, with the aim to inhibit invasion. This review provides an overview of the parasite adhesin protein families, the glideosome components, glideosome architecture, and discuss recent work regarding alternative models.
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Affiliation(s)
- Lauren E Boucher
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, USA; Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, USA.
| | - Jürgen Bosch
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, USA; Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, 615 N Wolfe St, Baltimore, MD 21205, USA.
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41
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Crystal structure of Plasmodium knowlesi apical membrane antigen 1 and its complex with an invasion-inhibitory monoclonal antibody. PLoS One 2015; 10:e0123567. [PMID: 25886591 PMCID: PMC4401722 DOI: 10.1371/journal.pone.0123567] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/05/2015] [Indexed: 11/30/2022] Open
Abstract
The malaria parasite Plasmodium knowlesi, previously associated only with infection of macaques, is now known to infect humans as well and has become a significant public health problem in Southeast Asia. This species should therefore be targeted in vaccine and therapeutic strategies against human malaria. Apical Membrane Antigen 1 (AMA1), which plays a role in Plasmodium merozoite invasion of the erythrocyte, is currently being pursued in human vaccine trials against P. falciparum. Recent vaccine trials in macaques using the P. knowlesi orthologue PkAMA1 have shown that it protects against infection by this parasite species and thus should be developed for human vaccination as well. Here, we present the crystal structure of Domains 1 and 2 of the PkAMA1 ectodomain, and of its complex with the invasion-inhibitory monoclonal antibody R31C2. The Domain 2 (D2) loop, which is displaced upon binding the Rhoptry Neck Protein 2 (RON2) receptor, makes significant contacts with the antibody. R31C2 inhibits binding of the Rhoptry Neck Protein 2 (RON2) receptor by steric blocking of the hydrophobic groove and by preventing the displacement of the D2 loop which is essential for exposing the complete binding site on AMA1. R31C2 recognizes a non-polymorphic epitope and should thus be cross-strain reactive. PkAMA1 is much less polymorphic than the P. falciparum and P. vivax orthologues. Unlike these two latter species, there are no polymorphic sites close to the RON2-binding site of PkAMA1, suggesting that P. knowlesi has not developed a mechanism of immune escape from the host’s humoral response to AMA1.
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Pihan E, Delgadillo RF, Tonkin ML, Pugnière M, Lebrun M, Boulanger MJ, Douguet D. Computational and biophysical approaches to protein-protein interaction inhibition of Plasmodium falciparum AMA1/RON2 complex. J Comput Aided Mol Des 2015; 29:525-39. [PMID: 25822046 DOI: 10.1007/s10822-015-9842-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Accepted: 03/25/2015] [Indexed: 11/30/2022]
Abstract
Invasion of the red blood cell by Plasmodium falciparum parasites requires formation of an electron dense circumferential ring called the Moving Junction (MJ). The MJ is anchored by a high affinity complex of two parasite proteins: Apical Membrane Antigen 1 (PfAMA1) displayed on the surface of the parasite and Rhoptry Neck Protein 2 that is discharged from the parasite and imbedded in the membrane of the host cell. Structural studies of PfAMA1 revealed a conserved hydrophobic groove localized to the apical surface that coordinates RON2 and invasion inhibitory peptides. In the present work, we employed computational and biophysical methods to identify competitive P. falciparum AMA1-RON2 inhibitors with the goal of exploring the 'druggability' of this attractive antimalarial target. A virtual screen followed by molecular docking with the PfAMA1 crystal structure was performed using an eight million compound collection that included commercial molecules, the ChEMBL malaria library and approved drugs. The consensus approach resulted in the selection of inhibitor candidates. We also developed a fluorescence anisotropy assay using a modified inhibitory peptide to experimentally validate the ability of the selected compounds to inhibit the AMA1-RON2 interaction. Among those, we identified one compound that displayed significant inhibition. This study offers interesting clues to improve the throughput and reliability of screening for new drug leads.
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Affiliation(s)
- Emilie Pihan
- Institut de Pharmacologie Moléculaire et Cellulaire, Université de Nice Sophia-Antipolis, CNRS, UMR 7275, 660, Route des Lucioles, Sophia Antipolis, 06560, Valbonne, France
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43
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Bioinformatic Identification of Peptidomimetic-Based Inhibitors against Plasmodium falciparum Antigen AMA1. Malar Res Treat 2014; 2014:642391. [PMID: 25580351 PMCID: PMC4281401 DOI: 10.1155/2014/642391] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 11/18/2014] [Indexed: 11/17/2022] Open
Abstract
Plasmodium falciparum apical membrane antigen 1 (PfAMA1) is a valuable vaccine candidate and exported on the merozoite surface at the time of erythrocyte invasion. PfAMA1 interacts with rhoptry neck protein PfRON2, a component of the rhoptry protein complex, which forms the tight junction at the time of invasion. Phage display studies have identified a 15-residue (F1) and a 20-residue (R1) peptide that bind to PfAMA1 and block the invasion of erythrocytes. Cocrystal structures of central region of PfAMA1 containing disulfide-linked clusters (domains I and II) with R1 peptide and a peptide derived from PfRON2 showed strong structural similarity in binding. The peptides bound to a hydrophobic groove surrounded by domain I and II loops. In this study, peptidomimetics based on the crucial PfAMA1-binding residues of PfRON2 peptide have been identified. Top 5 peptidomimetics when checked for their docking on the region of PfAMA1 encompassing the hydrophobic groove were found to dock on the groove. Drug-like molecules having structural similarity to the top 5 peptidomimetics were identified based on their binding ability to PfAMA1 hydrophobic groove in blind docking. These inhibitors provide potential lead compounds, which could be used in the development of antimalarials targeting PfAMA1.
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44
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Lim SS, Yang W, Krishnarjuna B, Kannan Sivaraman K, Chandrashekaran IR, Kass I, MacRaild CA, Devine SM, Debono CO, Anders RF, Scanlon MJ, Scammells PJ, Norton RS, McGowan S. Structure and dynamics of apical membrane antigen 1 from Plasmodium falciparum FVO. Biochemistry 2014; 53:7310-20. [PMID: 25360546 DOI: 10.1021/bi5012089] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apical membrane antigen 1 (AMA1) interacts with RON2 to form a protein complex that plays a key role in the invasion of host cells by malaria parasites. Blocking this protein-protein interaction represents a potential route to controlling malaria and related parasitic diseases, but the polymorphic nature of AMA1 has proven to be a major challenge to vaccine-induced antibodies and peptide inhibitors exerting strain-transcending inhibitory effects. Here we present the X-ray crystal structure of AMA1 domains I and II from Plasmodium falciparum strain FVO. We compare our new structure to those of AMA1 from P. falciparum 3D7 and Plasmodium vivax. A combination of normalized B factor analysis and computational methods has been used to investigate the flexibility of the domain I loops and how this correlates with their roles in determining the strain specificity of human antibody responses and inhibitory peptides. We also investigated the domain II loop, a key region involved in inhibitor binding, by comparison of multiple AMA1 crystal structures. Collectively, these results provide valuable insights that should contribute to the design of strain-transcending agents targeting P. falciparum AMA1.
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Affiliation(s)
- San Sui Lim
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville, Victoria 3052, Australia
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45
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Esmaeili Rastaghi AR, Nedaei F, Nahrevanian H, Hoseinkhan N. Genetic diversity and effect of natural selection at apical membrane antigen-1 (AMA-1) among Iranian Plasmodium vivax isolates. Folia Parasitol (Praha) 2014. [DOI: 10.14411/fp.2014.048] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Tonkin ML, Crawford J, Lebrun ML, Boulanger MJ. Babesia divergens and Neospora caninum apical membrane antigen 1 structures reveal selectivity and plasticity in apicomplexan parasite host cell invasion. Protein Sci 2014; 22:114-27. [PMID: 23169033 DOI: 10.1002/pro.2193] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 10/02/2012] [Accepted: 10/05/2012] [Indexed: 11/09/2022]
Abstract
Host cell invasion by the obligate intracellular apicomplexan parasites, including Plasmodium (malaria) and Toxoplasma (toxoplasmosis), requires a step-wise mechanism unique among known host-pathogen interactions. A key step is the formation of the moving junction (MJ) complex, a circumferential constriction between the apical tip of the parasite and the host cell membrane that traverses in a posterior direction to enclose the parasite in a protective vacuole essential for intracellular survival. The leading model of MJ assembly proposes that Rhoptry Neck Protein 2 (RON2) is secreted into the host cell and integrated into the membrane where it serves as the receptor for apical membrane antigen 1 (AMA1) on the parasite surface. We have previously demonstrated that the AMA1-RON2 interaction is an effective target for inhibiting apicomplexan invasion. To better understand the AMA1-dependant molecular recognition events that promote invasion, including the significant AMA1-RON2 interaction, we present the structural characterization of AMA1 from the apicomplexan parasites Babesia divergens (BdAMA1) and Neospora caninum (NcAMA1) by X-ray crystallography. These studies offer intriguing structural insight into the RON2-binding surface groove in the AMA1 apical domain, which shows clear evidence for receptor-ligand co-evolution, and the hyper variability of the membrane proximal domain, which in Plasmodium is responsible for direct binding to erythrocytes. By incorporating the structural analysis of BdAMA1 and NcAMA1 with existing AMA1 structures and complexes we were able to define conserved pockets in the AMA1 apical groove that could be targeted for the design of broadly reactive therapeutics.
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Affiliation(s)
- Michelle L Tonkin
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, V8W 3P6, Canada
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47
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Harvey KL, Yap A, Gilson PR, Cowman AF, Crabb BS. Insights and controversies into the role of the key apicomplexan invasion ligand, Apical Membrane Antigen 1. Int J Parasitol 2014; 44:853-7. [PMID: 25157917 DOI: 10.1016/j.ijpara.2014.08.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Revised: 08/04/2014] [Accepted: 08/06/2014] [Indexed: 10/24/2022]
Abstract
Apicomplexan parasites are obligate intracellular pathogens that cause a host of human and animal diseases. These parasites have developed a universal mechanism of invasion involving formation of a 'moving junction' that provides a stable anchoring point through which the parasite invades host cells. The composition of the moving junction, particularly the presence of the protein Apical Membrane Antigen 1 (AMA1), has recently been the subject of some controversy. In this commentary we review findings that led to the current model of the moving junction complex and dissect the major conflicts to determine whether a substantial reassessment of the role of AMA1 is justified.
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Affiliation(s)
- Katherine L Harvey
- Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Alan Yap
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 3010, Australia; Infection and Immunity Division, Walter and Eliza Hall Institute, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Paul R Gilson
- Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Immunology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Alan F Cowman
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 3010, Australia; Infection and Immunity Division, Walter and Eliza Hall Institute, 1G Royal Parade, Parkville, Victoria 3052, Australia
| | - Brendan S Crabb
- Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne, Victoria 3004, Australia; Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria 3010, Australia; Department of Immunology, Monash University, Wellington Road, Clayton, Victoria 3800, Australia.
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48
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Amarasinghe S, Kathriarachchi H, Udagama P. Conserved regions of Plasmodium vivax potential vaccine candidate antigens in Sri Lanka: conscious in silico analysis of prospective conformational epitope regions. ASIAN PAC J TROP MED 2014; 7:832-40. [PMID: 25129470 DOI: 10.1016/s1995-7645(14)60146-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 06/20/2014] [Accepted: 08/22/2014] [Indexed: 10/24/2022] Open
Abstract
OBJECTIVES To do mapping and modeling of conformational B cell epitope regions of highly conserved and protective regions of three merozoitecandidate vaccine proteins of Plasmodium vivax (P. vivax), ie. merozoite purface protein-1 (PvMSP-1), apical membrane antigen -1 domain ∏ (PvAMA1-D∏) and region ∏ of the Duffy binding protein (PvDBP∏), and to analyze the immunogenic properties of these predicted epitopes. METHODS 3-D structures of amino acid haplotypes from Sri Lanka (available in GeneBank) of PvMSP-119 (n=27), PvAMA1-D∏ (n=21) and PvDBP∏ (n=33) were modeled. SEPPA, selected as the best online server was used for conformational epitope predictions, while prediction and modeling of protein structure and properties related to immunogenicity was carried out with Geno3D server, SCRATCH Protein Server, NetSurfP Server and standalonesoftware, Genious 5.4.4. RESULTS SEPPA revealed that regions of predicted conformational epitopes formed 4 clusters in PvMSP-I19, and 3 clusters each in PvAMA1-D∏ and PvDBP∏, all of which displayed a high degree of hydrophilicity, contained solvent exposed residues, displayed high probability of antigenicity and showed positive antigenic propensity values, that indicated high degree of immunogenicity. CONCLUSIONS Findings of this study revealed and confirmed that different parts of the sequences of each of the conserved regions of the three selected potential vaccine candidate antigens of P. vivax are important with regard to conformational epitope prediction that warrants further laboratory experimental investigations in in vivo animal models.
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Affiliation(s)
- Shanika Amarasinghe
- Department of Plant Sciences, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka
| | - Hashendra Kathriarachchi
- Department of Plant Sciences, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka
| | - Preethi Udagama
- Department of Zoology, Faculty of Science, University of Colombo, CumarathungaMunidasaMawatha, Colombo 03, Sri Lanka.
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Immunization with a functional protein complex required for erythrocyte invasion protects against lethal malaria. Proc Natl Acad Sci U S A 2014; 111:10311-6. [PMID: 24958881 DOI: 10.1073/pnas.1409928111] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
An essential step in the invasion of red blood cells (RBCs) by Plasmodium falciparum (Pf) merozoites is the binding of rhoptry neck protein 2 (RON2) to the hydrophobic groove of apical membrane antigen 1 (AMA1), triggering junction formation between the apical end of the merozoite and the RBC surface to initiate invasion. Vaccination with AMA1 provided protection against homologous parasites in one of two phase 2 clinical trials; however, despite its ability to induce high-titer invasion-blocking antibodies in a controlled human challenge trial, the vaccine conferred little protection even against the homologous parasite. Here we provide evidence that immunization with an AMA1-RON2 peptide complex, but not with AMA1 alone, provided complete protection against a lethal Plasmodium yoelii challenge in mice. Significantly, IgG from mice immunized with the complex transferred protection. Furthermore, IgG from PfAMA1-RON2-immunized animals showed enhanced invasion inhibition compared with IgG elicited by AMA1 alone. Interestingly, this qualitative increase in inhibitory activity appears to be related, at least in part, to a switch in the proportion of IgG specific for certain loop regions in AMA1 surrounding the binding site of RON2. Antibodies induced by the complex were not sufficient to block the FVO strain heterologous parasite, however, reinforcing the need to include multiallele AMA1 to cover polymorphisms. Our results suggest that AMA1 subunit vaccines may be highly effective when presented to the immune system as an invasion complex with RON2.
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50
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Sharon J, Rynkiewicz MJ, Lu Z, Yang CY. Discovery of protective B-cell epitopes for development of antimicrobial vaccines and antibody therapeutics. Immunology 2014; 142:1-23. [PMID: 24219801 PMCID: PMC3992043 DOI: 10.1111/imm.12213] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2013] [Revised: 11/05/2013] [Accepted: 11/08/2013] [Indexed: 01/07/2023] Open
Abstract
Protective antibodies play an essential role in immunity to infection by neutralizing microbes or their toxins and recruiting microbicidal effector functions. Identification of the protective B-cell epitopes, those parts of microbial antigens that contact the variable regions of the protective antibodies, can lead to development of antibody therapeutics, guide vaccine design, enable assessment of protective antibody responses in infected or vaccinated individuals, and uncover or localize pathogenic microbial functions that could be targeted by novel antimicrobials. Monoclonal antibodies are required to link in vivo or in vitro protective effects to specific epitopes and may be obtained from experimental animals or from humans, and their binding can be localized to specific regions of antigens by immunochemical assays. The epitopes are then identified with mapping methods such as X-ray crystallography of antigen-antibody complexes, antibody inhibition of hydrogen-deuterium exchange in the antigen, antibody-induced alteration of the nuclear magnetic resonance spectrum of the antigen, and experimentally validated computational docking of antigen-antibody complexes. The diversity in shape, size and structure of protective B-cell epitopes, and the increasing importance of protective B-cell epitope discovery to development of vaccines and antibody therapeutics are illustrated through examples from different microbe categories, with emphasis on epitopes targeted by broadly neutralizing antibodies to pathogens of high antigenic variation. Examples include the V-shaped Ab52 glycan epitope in the O-antigen of Francisella tularensis, the concave CR6261 peptidic epitope in the haemagglutinin stem of influenza virus H1N1, and the convex/concave PG16 glycopeptidic epitope in the gp120 V1/V2 loop of HIV type 1.
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MESH Headings
- Animals
- Antibodies, Bacterial/immunology
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Neutralizing/immunology
- Antibodies, Neutralizing/therapeutic use
- Antibodies, Viral/immunology
- Antigen-Antibody Reactions
- Antigens, Bacterial/chemistry
- Antigens, Bacterial/immunology
- Antigens, Viral/chemistry
- Antigens, Viral/immunology
- Bacterial Vaccines/immunology
- Bacterial Vaccines/therapeutic use
- Epitope Mapping
- Epitopes, B-Lymphocyte/chemistry
- Epitopes, B-Lymphocyte/immunology
- Humans
- Models, Molecular
- Protein Conformation
- Viral Vaccines/immunology
- Viral Vaccines/therapeutic use
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Affiliation(s)
- Jacqueline Sharon
- Department of Pathology and Laboratory Medicine, Boston University School of MedicineBoston, MA, USA
| | - Michael J Rynkiewicz
- Department of Physiology and Biophysics, Boston University School of MedicineBoston, MA, USA
| | - Zhaohua Lu
- Department of Pathology and Laboratory Medicine, Boston University School of MedicineBoston, MA, USA
| | - Chiou-Ying Yang
- Department of Pathology and Laboratory Medicine, Boston University School of MedicineBoston, MA, USA
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