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Alkema M, Smit MJ, Marin-Mogollon C, Totté K, Teelen K, van Gemert GJ, van de Vegte-Bolmer M, Mordmüller BG, Reimer JM, Lövgren-Bengtsson KL, Sauerwein RW, Bousema T, Plieskatt J, Theisen M, Jore MM, McCall MBB. A Pfs48/45-based vaccine to block Plasmodium falciparum transmission: phase 1, open-label, clinical trial. BMC Med 2024; 22:170. [PMID: 38649867 PMCID: PMC11036667 DOI: 10.1186/s12916-024-03379-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 04/02/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND The stalling global progress in malaria control highlights the need for novel tools for malaria elimination, including transmission-blocking vaccines. Transmission-blocking vaccines aim to induce human antibodies that block parasite development in the mosquito and mosquitoes becoming infectious. The Pfs48/45 protein is a leading Plasmodium falciparum transmission-blocking vaccine candidate. The R0.6C fusion protein, consisting of Pfs48/45 domain 3 (6C) and the N-terminal region of P. falciparum glutamate-rich protein (R0), has previously been produced in Lactococcus lactis and elicited functional antibodies in rodents. Here, we assess the safety and transmission-reducing efficacy of R0.6C adsorbed to aluminium hydroxide with and without Matrix-M™ adjuvant in humans. METHODS In this first-in-human, open-label clinical trial, malaria-naïve adults, aged 18-55 years, were recruited at the Radboudumc in Nijmegen, the Netherlands. Participants received four intramuscular vaccinations on days 0, 28, 56 and 168 with either 30 µg or 100 µg of R0.6C and were randomised for the allocation of one of the two different adjuvant combinations: aluminium hydroxide alone, or aluminium hydroxide combined with Matrix-M1™ adjuvant. Adverse events were recorded from inclusion until 84 days after the fourth vaccination. Anti-R0.6C and anti-6C IgG titres were measured by enzyme-linked immunosorbent assay. Transmission-reducing activity of participants' serum and purified vaccine-specific immunoglobulin G was assessed by standard membrane feeding assays using laboratory-reared Anopheles stephensi mosquitoes and cultured P. falciparum gametocytes. RESULTS Thirty-one participants completed four vaccinations and were included in the analysis. Administration of all doses was safe and well-tolerated, with one related grade 3 adverse event (transient fever) and no serious adverse events occurring. Anti-R0.6C and anti-6C IgG titres were similar between the 30 and 100 µg R0.6C arms, but higher in Matrix-M1™ arms. Neat participant sera did not induce significant transmission-reducing activity in mosquito feeding experiments, but concentrated vaccine-specific IgGs purified from sera collected two weeks after the fourth vaccination achieved up to 99% transmission-reducing activity. CONCLUSIONS R0.6C/aluminium hydroxide with or without Matrix-M1™ is safe, immunogenic and induces functional Pfs48/45-specific transmission-blocking antibodies, albeit at insufficient serum concentrations to result in transmission reduction by neat serum. Future work should focus on identifying alternative vaccine formulations or regimens that enhance functional antibody responses. TRIAL REGISTRATION The trial is registered with ClinicalTrials.gov under identifier NCT04862416.
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Affiliation(s)
- M Alkema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - M J Smit
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - C Marin-Mogollon
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - K Totté
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - K Teelen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - G J van Gemert
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - M van de Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - B G Mordmüller
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | | | - R W Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
- Present Address: TropIQ Health Sciences, Nijmegen, the Netherlands
| | - T Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - J Plieskatt
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
| | - M Theisen
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - M M Jore
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - M B B McCall
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands.
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Drakeley CJ, Bousema JT, Akim NIJ, Teelen K, Roeffen W, Lensen AH, Bolmer M, Eling W, Sauerwein RW. Transmission-reducing immunity is inversely related to age in Plasmodium falciparum gametocyte carriers. Parasite Immunol 2006; 28:185-90. [PMID: 16629703 DOI: 10.1111/j.1365-3024.2005.00818.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Immunity to the sexual stages of Plasmodium falciparum is induced during natural infections and can significantly reduce the transmission of parasites to mosquitoes (transmission reducing activity; TRA) but little is known about how these responses develop with increasing age/exposure to malaria. Routinely TRA is measured in the standard membrane feeding assay (SMFA). Sera were collected from a total of 199 gametocyte carriers (median age 4 years, quartiles 2 and 9 years) near Ifakara, Tanzania; 128 samples were tested in the SMFA and generated TRA data classified as a reduction of > 50% and > 90% of transmission. TRA of > 50% was highest in young children (aged 1-2) with a significant decline with age (chi(2) trend = 5.79, P = 0.016) and in logistic regression was associated with prevalence of antibodies to both Pfs230 and Pfs48/45 (OR 4.03, P = 0.011 and OR 2.43 P = 0.059, respectively). A TRA of > 90% reduction in transmission was not age related but was associated with antibodies to Pfs48/45 (OR 2.36, P = 0.055). Our data confirm that antibodies are an important component of naturally induced TRA. However, whilst a similar but small proportion of individuals at all ages have TRA > 90%, the gradual deterioration of TRA > 50% with age suggests decreased antibody concentration or affinity. This may be due to decreased exposure to gametocytes, probably as a result of increased asexual and/or gametocyte specific immunity.
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Affiliation(s)
- C J Drakeley
- Ifakara Health Research and Development Centre, Ifakara, Tanzania.
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Drakeley CJ, Eling W, Teelen K, Bousema JT, Sauerwein R, Greenwood BM, Targett GAT. Parasite infectivity and immunity to Plasmodium falciparum gametocytes in Gambian children. Parasite Immunol 2004; 26:159-65. [PMID: 15367293 DOI: 10.1111/j.0141-9838.2004.00696.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Immunity to the sexual stages of Plasmodium falciparum can be induced during natural infections. Characterization of this immunity may facilitate the design of a transmission-blocking vaccine (TBV). This study aimed to assess the prevalence and serological correlates of functional transmission-blocking immunity in Gambian children (aged 1-4 years old) who were P. falciparum gametocyte carriers. Serological assays showed 100% response to fixed, whole parasites but only 42% to live gametes. Responses to the antigens Pfs230 and Pfs48/45 were 54.1% and 37.3%, respectively, in an IgG1 ELISA. 14/55 sera were capable of reducing the infectivity of laboratory isolate NF54 in a standard membrane-feeding assay (SMFA). This activity was strongly correlated with IgG1 responses to Pfs48/45 (r = 0.49, P < 0.001) and to a serological reaction with epitopes of the same molecule (r = 0.38, P = 0.003). A weaker correlation was observed with IgG1 to Pfs230 (r = 0.29, P = 0.03). In direct membrane feeding assays (DMFA) with autologous isolates, sera from 4/29 children showed transmission-blocking activity. There was no correlation with serological assays and the DMFA or between the SMFA and DMFA. This may be caused by variation in sexual stage antigens and/or alternative modes of transmission-blocking immunity, both of which have implications for vaccine implementation.
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Affiliation(s)
- C J Drakeley
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel St., London WC1E 7HT, UK.
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Roeffen WF, Raats JM, Teelen K, Hoet RM, Eling WM, van Venrooij WJ, Sauerwein RW. Recombinant human antibodies specific for the Pfs48/45 protein of the malaria parasite Plasmodium falciparum. J Biol Chem 2001; 276:19807-11. [PMID: 11279092 DOI: 10.1074/jbc.m100562200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report the first construction of two combinatorial human phage display libraries derived from malaria-immune patients. Specific single-chain Fv fragments (scFv) against Pfs48/45, a gamete surface protein of the sexual stages of Plasmodium falciparum, were selected and analyzed extensively. The selected scFv reacted with the surface of extracellular sexual forms of the parasite and showed Pfs48/45 reactivity on immunoblot. The scFv inhibit binding of human malaria sera to native Pfs48/45 from gametocytes. Moreover, the scFv bind to target epitopes of Pfs48/45 exposed in natural infections. Sequence analysis of eight scFv clones specific for epitope III of Pfs48/45 revealed that these clones could be divided into one V(H) family-derived germ-line gene (V(H)1) and two V(L) family segments (V(L)2 and V(K)I).
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Affiliation(s)
- W F Roeffen
- Department of Medical Microbiology, University Medical Center St. Radboud, 6500 HB Nijmegen, The Netherlands.
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Roeffen W, Teelen K, van As J, vd Vegte-Bolmer M, Eling W, Sauerwein R. Plasmodium falciparum: production and characterization of rat monoclonal antibodies specific for the sexual-stage Pfs48/45 antigen. Exp Parasitol 2001; 97:45-9. [PMID: 11207113 DOI: 10.1006/expr.2000.4586] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- W Roeffen
- Department of Medical Microbiology, University Medical Centre, St. Radboud, Nijmegen, 6500 HB, The Netherlands
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Roeffen W, Mulder B, Teelen K, Bolmer M, Eling W, Targett GA, Beckers PJ, Sauerwein R. Association between anti-Pfs48/45 reactivity and P. falciparum transmission-blocking activity in sera from Cameroon. Parasite Immunol 1996; 18:103-9. [PMID: 9223163 DOI: 10.1046/j.1365-3024.1996.d01-54.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pfs48/45, a sexual stage parasite protein doublet of P. falciparum, is a target of antibodies which inhibit the development of the parasite in the mosquito. Twenty-eight (54%) out of 52 sera of gametocyte carriers from Cameroon reduced infectivity in the mosquito membrane feeding bioassay to less than 20% of the controls. These 52 sera were analysed by competition ELISAs for the presence of antibodies capable of competing the binding of six monoclonal antibodies (MoAbs) directed against five different epitopes on Pfs48/45. The percentage of these 52 Cameroon sera that competed with one of the MoAbs ranged from 13% (epitope I) to 33% (epitope IIc). Comparison of activity in the transmission-blocking assay (> or = 80%) and in the Pfs48/45 competition ELISA show a relative specificity of 100% (24 of 24) and a relative sensitivity of 75% (21 of 28). Non-blocking sera showed no competition with any of the MoAbs. These MoAbs were further used to study the diversity of epitopes among isolates of P. falciparum using a two-site ELISA. MoAbs against epitope I, III and V reacted with four different isolates whereas epitope II could be subdivided into three epitopes. None of the isolates reacted with MoAb 3G12 (epitope IV). Using these four different isolates, the competition ELISA titre varies from 1/20 to 1/80 and no significant differences are found between the isolates except for epitope II where only three out of 11 positives for epitope IIa were also positive for epitope IIc.
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Affiliation(s)
- W Roeffen
- University of Nijmegen, Department of Medical Microbiology, The Netherlands
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Roeffen W, Beckers PJ, Teelen K, Lensen T, Sauerwein RW, Meuwissen JH, Eling W. Plasmodium falciparum: a comparison of the activity of Pfs230-specific antibodies in an assay of transmission-blocking immunity and specific competition ELISAs. Exp Parasitol 1995; 80:15-26. [PMID: 7529717 DOI: 10.1006/expr.1995.1003] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The activity of monoclonal antibodies (mAbs) that specifically recognize the Plasmodium falciparum sexual stage-specific protein Pfs230 was analyzed. All mAbs reacted with the surface of extracellular sexual forms of the parasite in a suspension immunofluorescence antibody reaction and precipitated the Pfs230 protein from an NP-40 extract of surface radioiodinated macrogametes/zygotes. Only mAb that bound complement blocked transmission, whereas mAb that did not bind complement but competed with the complement-binding mAb for binding to the same epitope did not block transmission. These mAbs were used to develop Pfs230-specific competition ELISAs to analyze epitope diversity and to analyze the binding characteristics of anti-Pfs230 antibodies in human serum. Transmission-blocking (TB) antibodies in test/field sera competed in the competition ELISA for binding with epitope-specific, labeled mAbs against Pfs230. At least five different epitope regions could be defined with the competition ELISAs. All 46 sera from gametocyte carriers immunoprecipitated the Pfs230 molecule, while 19 of these sera blocked transmission in the bioassay. Five of the transmission-blocking and one of the nonblocking sera competed with monoclonal antibodies. A method comparison analysis was used to determine agreement between reactions in a competitive ELISA and the TB activity examined in the bioassay. The index of agreement kappa between outcomes of the bioassay and ELISA was fair to poor (kappa = 0.25) but since its range includes values below 0 the relation between the data obtained by the bioassay and the competition ELISA can be explained by chance alone. The serological data did not reveal a correlation between immunoprecipitation of Pfs230 and TB activity.
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Affiliation(s)
- W Roeffen
- University of Nijmegen, Department of Medical Microbiology, The Netherlands
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Roeffen W, Lensen T, Mulder B, Teelen K, Sauerwein R, Van Druten J, Eling W, Meuwissen JH, Beckers PJ. A comparison of transmission-blocking activity with reactivity in a Plasmodium falciparum 48/45-kD molecule-specific competition enzyme-linked immunosorbent assay. Am J Trop Med Hyg 1995; 52:60-5. [PMID: 7856826 DOI: 10.4269/ajtmh.1995.52.60] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Monoclonal antibodies (MAbs) 32F1 and 32F3 react with two independent epitopes of a protein doublet with molecular weights of 48 and 45 kilodaltons (kD) expressed on the surface of Plasmodium falciparum (Pfs48/45) macrogametes and zygotes; only 32F3 blocks transmission. These MAbs were used to develop a Pfs48/45-specific competition enzyme-linked immunosorbent assay (ELISA) using 32F1 to capture antigen and labeled 32F3 for quantification and analysis of the contribution of antibodies in human serum to transmission-blocking activity. A comparison analysis was used to determine agreement of competition ELISA titers and transmission-blocking activity as observed in the bioassay in three groups of serum samples: 37 from European travelers with previous exposure to malaria, 56 from gametocyte carriers, and 66 from schoolchildren from a malaria-endemic area in Cameroon. The index of agreement between outcomes of the ELISA and transmission-blocking assay in gametocyte carriers and in travelers was specifically defined as fair-to-moderate; in schoolchildren the agreement was not significant. The combined analysis of all sera showed a significant and fair-to-moderate agreement between the results of the competition ELISA and the transmission-blocking assay, with a relative specificity of 94% (of 105 cases negative in the transmission-blocking assay, 99 were also negative in the competition ELISA) and a relative sensitivity of 44% (of 54 cases positive in the transmission-blocking assay, 24 were also positive in the competition ELISA). This study shows that a positive C48/45-ELISA is indicative for transmission-blocking activity in the mosquito assay, while a negative result does not exclude transmission-blocking activity.
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Affiliation(s)
- W Roeffen
- Department of Medical Microbiology, University of Nijmegen, The Netherlands
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Roeffen W, Lensen T, Mulder B, Teelen K, Sauerwein R, Eling W, Meuwissen JH, Beckers P. Transmission blocking immunity as observed in a feeder system and serological reactivity to Pfs 48/45 and Pfs230 in field sera. Mem Inst Oswaldo Cruz 1994; 89 Suppl 2:13-5. [PMID: 7565122 DOI: 10.1590/s0074-02761994000600004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Monoclonal antibodies (mAbs) and human sera from gametocyte carriers were applied in the bio-assay to test for their transmission-blocking capacity. Competition ELISA's have been developed for the detection of natural transmission blocking antibodies. Approximately 55% of the sera blocking in the bio-assay gave positive results in these competition ELISA's.
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Affiliation(s)
- W Roeffen
- University of Nijmegen, Department of Medical Microbiology, The Netherlands
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Roeffen W, Beckers PJ, Teelen K, Verhave JP, Eling W, Sauerwein R. Comparison of serological tests and bio-assay for malaria transmission blocking capacity in field sera. Parassitologia 1993; 35 Suppl:95-7. [PMID: 7694226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Competition ELISAs have been developed for natural transmission blocking antibodies. Approximately 50% of the sera blocking in the conventional mosquito feeding experiments, gave positive results in these competition ELISAs. Attempts to adapt competition ELISAs to a field application have been partly successful.
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Affiliation(s)
- W Roeffen
- University of Nijmegen, Department of Medical Microbiology, The Netherlands
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