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Article: Structure guided mimicry of an essential P. falciparum receptor-ligand complex enhances cross neutralizing antibodies.

Srinivasan, Prakash / Yanik, Sean / Venkatesh, Varsha / Parker, Michelle / Diouf, Ababacar / Sarkar, Deepti / Miura, Kazutoyo / Long, Carole / Boulanger, Martin

Research square

2023

Abstract: Invasion of human red blood cells (RBCs) ... ...

Abstract	Invasion of human red blood cells (RBCs) by
Language	English
Publishing date	2023-04-20
Publishing country	United States
Document type	Preprint
DOI	10.21203/rs.3.rs-2733434/v1
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Article ; Online: Evaluation of the precision of the Plasmodium knowlesi growth inhibition assay for Plasmodium vivax Duffy-binding protein-based malaria vaccine development.

Mertens, Jonas E / Rigby, Cassandra A / Bardelli, Martino / Quinkert, Doris / Hou, Mimi M / Diouf, Ababacar / Silk, Sarah E / Chitnis, Chetan E / Minassian, Angela M / Moon, Robert W / Long, Carole A / Draper, Simon J / Miura, Kazutoyo

Vaccine

2024

Abstract: Recent data indicate increasing disease burden and importance of Plasmodium vivax (Pv) malaria. A robust assay will be essential for blood-stage Pv vaccine development. Results of the in vitro growth inhibition assay (GIA) with transgenic P. knowlesi (Pk) ...

Abstract	Recent data indicate increasing disease burden and importance of Plasmodium vivax (Pv) malaria. A robust assay will be essential for blood-stage Pv vaccine development. Results of the in vitro growth inhibition assay (GIA) with transgenic P. knowlesi (Pk) parasites expressing the Pv Duffy-binding protein region II (PvDBPII) correlate with in vivo protection in the first PvDBPII controlled human malaria infection (CHMI) trials, making the PkGIA an ideal selection tool once the precision of the assay is defined. To determine the precision in percentage of inhibition in GIA (%GIA) and in GIA
Language	English
Publishing date	2024-05-03
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	605674-x
ISSN	1873-2518 ; 0264-410X
ISSN (online)	1873-2518
ISSN	0264-410X
DOI	10.1016/j.vaccine.2024.04.073
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Article ; Online: Structure guided mimicry of an essential P. falciparum receptor-ligand complex enhances cross neutralizing antibodies.

Yanik, Sean / Venkatesh, Varsha / Parker, Michelle L / Ramaswamy, Raghavendran / Diouf, Ababacar / Sarkar, Deepti / Miura, Kazutoyo / Long, Carole A / Boulanger, Martin J / Srinivasan, Prakash

Nature communications

2023 Volume 14, Issue 1, Page(s) 5879

Abstract: Invasion of human erythrocytes by Plasmodium falciparum (Pf) merozoites relies on the interaction between two parasite proteins: apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2). While antibodies to AMA1 provide limited protection ... ...

Abstract	Invasion of human erythrocytes by Plasmodium falciparum (Pf) merozoites relies on the interaction between two parasite proteins: apical membrane antigen 1 (AMA1) and rhoptry neck protein 2 (RON2). While antibodies to AMA1 provide limited protection against Pf in non-human primate malaria models, clinical trials using recombinant AMA1 alone (apoAMA1) yielded no protection due to insufficient functional antibodies. Immunization with AMA1 bound to RON2L, a 49-amino acid peptide from its ligand RON2, has shown superior protection by increasing the proportion of neutralizing antibodies. However, this approach relies on the formation of a complex in solution between the two vaccine components. To advance vaccine development, here we engineered chimeric antigens by replacing the AMA1 DII loop, displaced upon ligand binding, with RON2L. Structural analysis confirmed that the fusion chimera (Fusion-F
MeSH term(s)	Female ; Animals ; Rats ; Broadly Neutralizing Antibodies ; Ligands ; Cell Membrane ; Antibodies, Neutralizing ; Epitopes
Chemical Substances	Broadly Neutralizing Antibodies ; Ligands ; Antibodies, Neutralizing ; Epitopes
Language	English
Publishing date	2023-09-21
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-023-41636-5
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Article ; Online: Structure-based design of a strain transcending AMA1-RON2L malaria vaccine.

Patel, Palak N / Dickey, Thayne H / Diouf, Ababacar / Salinas, Nichole D / McAleese, Holly / Ouahes, Tarik / Long, Carole A / Miura, Kazutoyo / Lambert, Lynn E / Tolia, Niraj H

Nature communications

2023 Volume 14, Issue 1, Page(s) 5345

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 ... ...

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.
MeSH term(s)	Animals ; Mice ; Malaria Vaccines ; Antibodies, Neutralizing ; Cell Membrane ; Epitopes ; Immunization
Chemical Substances	Malaria Vaccines ; Antibodies, Neutralizing ; Epitopes
Language	English
Publishing date	2023-09-02
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, N.I.H., Extramural
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-023-40878-7
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Article ; Online: Assessment of precision in growth inhibition assay (GIA) using human anti-PfRH5 antibodies.

Miura, Kazutoyo / Diouf, Ababacar / Fay, Michael P / Barrett, Jordan R / Payne, Ruth O / Olotu, Ally I / Minassian, Angela M / Silk, Sarah E / Draper, Simon J / Long, Carole A

Malaria journal

2023 Volume 22, Issue 1, Page(s) 159

Abstract: Background: For blood-stage malaria vaccine development, the in vitro growth inhibition assay (GIA) has been widely used to evaluate functionality of vaccine-induced antibodies (Ab), and Plasmodium falciparum reticulocyte-binding protein homolog 5 (RH5) ...

Abstract	Background: For blood-stage malaria vaccine development, the in vitro growth inhibition assay (GIA) has been widely used to evaluate functionality of vaccine-induced antibodies (Ab), and Plasmodium falciparum reticulocyte-binding protein homolog 5 (RH5) is a leading blood-stage antigen. However, precision, also called "error of assay (EoA)", in GIA readouts and the source of EoA has not been evaluated systematically. Methods: In the Main GIA experiment, 4 different cultures of P. falciparum 3D7 parasites were prepared with red blood cells (RBC) collected from 4 different donors. For each culture, 7 different anti-RH5 Ab (either monoclonal or polyclonal Ab) were tested by GIA at two concentrations on three different days (168 data points). To evaluate sources of EoA in % inhibition in GIA (%GIA), a linear model fit was conducted including donor (source of RBC) and day of GIA as independent variables. In addition, 180 human anti-RH5 polyclonal Ab were tested in a Clinical GIA experiment, where each Ab was tested at multiple concentrations in at least 3 independent GIAs using different RBCs (5,093 data points). The standard deviation (sd) in %GIA and in GIA Results: The Main GIA experiment revealed that the RBC donor effect was much larger than the day effect, and an obvious donor effect was also observed in the Clinical GIA experiment. Both %GIA and log-transformed GIA Conclusions: The RBC donor effect (donor-to-donor variance on the same day) in GIA was much bigger than the day effect (day-to-day variance using the same donor's RBC) at least for the RH5 Ab evaluated in this study; thus, future GIA studies should consider the donor effect. In addition, the 95%CI for %GIA and GIA
MeSH term(s)	Humans ; Plasmodium falciparum ; Antibodies, Protozoan ; Malaria, Falciparum/parasitology ; Erythrocytes/parasitology ; Malaria Vaccines ; Antibodies, Viral ; Antigens, Protozoan
Chemical Substances	Antibodies, Protozoan ; Malaria Vaccines ; Antibodies, Viral ; Antigens, Protozoan
Language	English
Publishing date	2023-05-19
Publishing country	England
Document type	Journal Article
ZDB-ID	2091229-8
ISSN	1475-2875 ; 1475-2875
ISSN (online)	1475-2875
ISSN	1475-2875
DOI	10.1186/s12936-023-04591-6
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Article: Development and Qualification of an Antigen Integrity Assay for a

Miura, Kazutoyo / Pham, Thao P / Lee, Shwu-Maan / Plieskatt, Jordan / Diouf, Ababacar / Sagara, Issaka / Coelho, Camila H / Duffy, Patrick E / Wu, Yimin / Long, Carole A

Vaccines

2022 Volume 10, Issue 10

Abstract: During development of a subunit vaccine, monitoring integrity of the recombinant protein for process development and quality control is critical. Pfs230 is a leading malaria transmission blocking vaccine candidate and the first to reach a Phase 2 ... ...

Abstract	During development of a subunit vaccine, monitoring integrity of the recombinant protein for process development and quality control is critical. Pfs230 is a leading malaria transmission blocking vaccine candidate and the first to reach a Phase 2 clinical trial. The Pfs230 protein is expressed on the surface of gametes, and plays an important role in male fertility. While the potency of Pfs230 protein can be determined by a standard membrane-feeding assay (SMFA) using antibodies from immunized subjects, the precision of a general in vivo potency study is known to be poor and is also time-consuming. Therefore, using a well-characterized Pfs230 recombinant protein and two human anti-Pfs230 monoclonal antibodies (mAbs), which have functional activity judged by SMFA, a sandwich ELISA-based in vitro potency assay, called the Antigen Integrity Assay (AIA), was developed. Multiple validation parameters of AIA were evaluated to qualify the assay following International Conference on Harmonization (ICH) Q2(R1) guidelines. The AIA is a high throughput assay and demonstrated excellent precision (3.2 and 5.4% coefficients of variance for intra- and inter-assay variability, respectively) and high sensitivity (>12% impurity in a sample can be detected). General methodologies and the approach to assay validation described herein are amenable to any subunit vaccine as long as more than two functional, non-competing mAbs are available. Thus, this study supports future subunit vaccine development.
Language	English
Publishing date	2022-09-28
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2703319-3
ISSN	2076-393X
ISSN	2076-393X
DOI	10.3390/vaccines10101628
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Article ; Online: Elucidating functional epitopes within the N-terminal region of malaria transmission blocking vaccine antigen Pfs230.

Miura, Kazutoyo / Takashima, Eizo / Pham, Thao P / Deng, Bingbing / Zhou, Luwen / Huang, Wei-Chiao / Diouf, Ababacar / Gebremicale, Yonas T / Tachibana, Mayumi / Ishino, Tomoko / Richter King, C / Lovell, Jonathan F / Long, Carole A / Tsuboi, Takafumi

NPJ vaccines

2022 Volume 7, Issue 1, Page(s) 4

Abstract: Pfs230 is a leading malaria transmission blocking vaccine (TBV) candidate. Comprising 3135 amino acids (aa), the large size of Pfs230 necessitates the use of sub-fragments as vaccine immunogens. Therefore, determination of which regions induce functional ...

Abstract	Pfs230 is a leading malaria transmission blocking vaccine (TBV) candidate. Comprising 3135 amino acids (aa), the large size of Pfs230 necessitates the use of sub-fragments as vaccine immunogens. Therefore, determination of which regions induce functional antibody responses is essential. We previously reported that of 27 sub-fragments spanning the entire molecule, only five induced functional antibodies. A "functional" antibody is defined herein as one that inhibits Plasmodium falciparum parasite development in mosquitoes in a standard membrane-feeding assay (SMFA). These five sub-fragments were found within the aa 443-1274 range, and all contained aa 543-730. Here, we further pinpoint the location of epitopes within Pfs230 that are recognized by functional antibodies using antibody depletion and enrichment techniques. Functional epitopes were not found within the aa 918-1274 region. Within aa 443-917, further analysis showed the existence of functional epitopes not only within the aa 543-730 region but also outside of it. Affinity-purified antibodies using a synthetic peptide matching aa 543-588 showed activity in the SMFA. Immunization with a synthetic peptide comprising this segment, formulated either as a carrier-protein conjugate vaccine or with a liposomal vaccine adjuvant system, induced antibodies in mice that were functional in the SMFA. These findings provide key insights for Pfs230-based vaccine design and establish the feasibility for the use of synthetic peptide antigens for a malaria TBV.
Language	English
Publishing date	2022-01-13
Publishing country	England
Document type	Journal Article
ISSN	2059-0105
ISSN (online)	2059-0105
DOI	10.1038/s41541-021-00423-3
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Article ; Online: Neutralizing and interfering human antibodies define the structural and mechanistic basis for antigenic diversion.

Patel, Palak N / Dickey, Thayne H / Hopp, Christine S / Diouf, Ababacar / Tang, Wai Kwan / Long, Carole A / Miura, Kazutoyo / Crompton, Peter D / Tolia, Niraj H

Nature communications

2022 Volume 13, Issue 1, Page(s) 5888

Abstract: Defining mechanisms of pathogen immune evasion and neutralization are critical to develop potent vaccines and therapies. Merozoite Surface Protein 1 (MSP-1) is a malaria vaccine antigen and antibodies to MSP-1 are associated with protection from disease. ...

Abstract	Defining mechanisms of pathogen immune evasion and neutralization are critical to develop potent vaccines and therapies. Merozoite Surface Protein 1 (MSP-1) is a malaria vaccine antigen and antibodies to MSP-1 are associated with protection from disease. However, MSP-1-based vaccines performed poorly in clinical trials in part due to a limited understanding of the protective antibody response to MSP-1 and of immune evasion by antigenic diversion. Antigenic diversion was identified as a mechanism wherein parasite neutralization by a MSP-1-specific rodent antibody was disrupted by MSP-1-specific non-inhibitory blocking/interfering antibodies. Here, we investigated a panel of MSP-1-specific naturally acquired human monoclonal antibodies (hmAbs). Structures of multiple hmAbs with diverse neutralizing potential in complex with MSP-1 revealed the epitope of a potent strain-transcending hmAb. This neutralizing epitope overlaps with the epitopes of high-affinity non-neutralizing hmAbs. Strikingly, the non-neutralizing hmAbs outcompete the neutralizing hmAb enabling parasite survival. These findings demonstrate the structural and mechanistic basis for a generalizable pathogen immune evasion mechanism through neutralizing and interfering human antibodies elicited by antigenic diversion, and provides insights required to develop potent and durable malaria interventions.
MeSH term(s)	Antibodies, Blocking ; Antibodies, Monoclonal ; Antibodies, Neutralizing ; Antigens, Protozoan ; Epitopes ; Humans ; Malaria Vaccines ; Merozoite Surface Protein 1
Chemical Substances	Antibodies, Blocking ; Antibodies, Monoclonal ; Antibodies, Neutralizing ; Antigens, Protozoan ; Epitopes ; Malaria Vaccines ; Merozoite Surface Protein 1
Language	English
Publishing date	2022-10-06
Publishing country	England
Document type	Journal Article ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, N.I.H., Intramural
ZDB-ID	2553671-0
ISSN	2041-1723 ; 2041-1723
ISSN (online)	2041-1723
ISSN	2041-1723
DOI	10.1038/s41467-022-33336-3
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Article ; Online: Antibodies from malaria-exposed Malians generally interact additively or synergistically with human vaccine-induced RH5 antibodies.

Willcox, Alexandra C / Huber, Alex S / Diouf, Ababacar / Barrett, Jordan R / Silk, Sarah E / Pulido, David / King, Lloyd D W / Alanine, Daniel G W / Minassian, Angela M / Diakite, Mahamadou / Draper, Simon J / Long, Carole A / Miura, Kazutoyo

Cell reports. Medicine

2021 Volume 2, Issue 7, Page(s) 100326

Abstract: Reticulocyte-binding protein homolog 5 (RH5) is a ... ...

Abstract	Reticulocyte-binding protein homolog 5 (RH5) is a leading
MeSH term(s)	Adolescent ; Adult ; Aged ; Antibodies, Monoclonal/immunology ; Antibodies, Neutralizing/immunology ; Antibodies, Protozoan/immunology ; Antimalarials/metabolism ; Child ; Child, Preschool ; Female ; Humans ; Immunoglobulin G/immunology ; Infant ; Malaria Vaccines/immunology ; Malaria, Falciparum/epidemiology ; Malaria, Falciparum/immunology ; Male ; Mali ; Middle Aged ; Plasmodium falciparum/growth & development ; Plasmodium falciparum/immunology ; Vaccination ; Young Adult
Chemical Substances	Antibodies, Monoclonal ; Antibodies, Neutralizing ; Antibodies, Protozoan ; Antimalarials ; Immunoglobulin G ; Malaria Vaccines
Language	English
Publishing date	2021-06-21
Publishing country	United States
Document type	Clinical Trial, Phase I ; Clinical Trial, Phase II ; Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
ISSN	2666-3791
ISSN (online)	2666-3791
DOI	10.1016/j.xcrm.2021.100326
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Article ; Online: Strong concordance between percent inhibition in oocyst and sporozoite intensities in a Plasmodium falciparum standard membrane-feeding assay.

Miura, Kazutoyo / Swihart, Bruce J / Deng, Bingbing / Zhou, Luwen / Pham, Thao P / Diouf, Ababacar / Fay, Michael P / Long, Carole A

Parasites & vectors

2019 Volume 12, Issue 1, Page(s) 206

Abstract: Background: Effective malaria transmission-blocking vaccines (TBVs) can support malaria eradication programmes, and the standard membrane-feeding assay (SMFA) has been used as a "gold standard" assay for TBV development. However, in SMFA, the inhibitory ...

Abstract	Background: Effective malaria transmission-blocking vaccines (TBVs) can support malaria eradication programmes, and the standard membrane-feeding assay (SMFA) has been used as a "gold standard" assay for TBV development. However, in SMFA, the inhibitory activity is commonly measured at oocyst stage of parasites, while it is the sporozoites which transmit malaria from a mosquito to a human. A handful of studies have shown that there is a positive correlation between oocyst and sporozoite intensities. However, no study has been completed to compare inhibition levels in oocyst and sporozoite intensities in the presence of transmission-blocking (TB) antibodies. Results: Plasmodium falciparum NF54 gametocytes were fed to Anopheles stephensi mosquitoes with or without anti-Pfs25 or anti-Pfs48/45 TB antibodies in 15 independent assays. For each group, a portion of the mosquitoes was dissected for oocyst counts (day 8 after feed), and a portion of the remaining mosquitoes was dissected for sporozoite counts (day 16). This study covered a large range of oocyst and sporozoite intensities: 0.2 to 80.5 on average for oocysts, and 141 to 77,417 for sporozoites. The sporozoite data were well explained by a zero-inflated negative binomial model, regardless of the presence or absence of TB antibodies. Inhibition levels in both oocyst and sporozoite intensities were determined within the same groups in 9 independent assays. When the level of inhibition in sporozoite number (expressed as Log Mean Ratio, LMR; average number in a control group was divided by the one in a test group, then took a log of the ratio) was plotted against LMR in oocyst number, the best-fit slope of a linear regression was not different from 1 (the best estimate, 1.08; 95% confidence interval, 0.87 to 1.29). Furthermore, a Bland-Altman analysis showed a strong agreement between inhibitions in oocysts and in sporozoites. Conclusions: The results indicate that percent inhibition in oocyst intensity of a test sample can be directly converted to % inhibition in sporozoite intensity in P. falciparum SMFA. Therefore, if sporozoite intensity determines transmission rate from mosquitoes to humans, the percent inhibition in oocyst intensity measured by SMFA can be used to estimate the TBV efficacy.
MeSH term(s)	Animals ; Anopheles/parasitology ; Antibodies, Protozoan/immunology ; Feeding Behavior ; Female ; Humans ; Malaria/parasitology ; Malaria/prevention & control ; Malaria/transmission ; Malaria Vaccines/immunology ; Membranes, Artificial ; Oocysts/immunology ; Oocysts/physiology ; Plasmodium falciparum/immunology ; Plasmodium falciparum/physiology ; Sporozoites/immunology ; Sporozoites/physiology
Chemical Substances	Antibodies, Protozoan ; Malaria Vaccines ; Membranes, Artificial
Language	English
Publishing date	2019-05-06
Publishing country	England
Document type	Journal Article
ZDB-ID	2409480-8
ISSN	1756-3305 ; 1756-3305
ISSN (online)	1756-3305
ISSN	1756-3305
DOI	10.1186/s13071-019-3470-3
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