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van der Put RM, Metz B, Pieters RJ. Carriers and Antigens: New Developments in Glycoconjugate Vaccines. Vaccines (Basel) 2023; 11:vaccines11020219. [PMID: 36851097 PMCID: PMC9962112 DOI: 10.3390/vaccines11020219] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 01/05/2023] [Accepted: 01/15/2023] [Indexed: 01/20/2023] Open
Abstract
Glycoconjugate vaccines have proven their worth in the protection and prevention of infectious diseases. The introduction of the Haemophilus influenzae type b vaccine is the prime example, followed by other glycoconjugate vaccines. Glycoconjugate vaccines consist of two components: the carrier protein and the carbohydrate antigen. Current carrier proteins are tetanus toxoid, diphtheria toxoid, CRM197, Haemophilus protein D and the outer membrane protein complex of serogroup B meningococcus. Carbohydrate antigens have been produced mainly by extraction and purification from the original host. However, current efforts show great advances in the development of synthetically produced oligosaccharides and bioconjugation. This review evaluates the advances of glycoconjugate vaccines in the last five years. We focus on developments regarding both new carriers and antigens. Innovative developments regarding carriers are outer membrane vesicles, glycoengineered proteins, new carrier proteins, virus-like particles, protein nanocages and peptides. With regard to conjugated antigens, we describe recent developments in the field of antimicrobial resistance (AMR) and ESKAPE pathogens.
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Affiliation(s)
- Robert M.F. van der Put
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
- Correspondence:
| | - Bernard Metz
- Intravacc, P.O. Box 450, 3720 AL Bilthoven, The Netherlands
| | - Roland J. Pieters
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, P.O. Box 80082, 3508 TB Utrecht, The Netherlands
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2
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Scaria PV, Anderson C, Muratova O, Alani N, Trinh HV, Nadakal ST, Zaidi I, Lambert L, Beck Z, Barnafo EK, Rausch KM, Rowe C, Chen B, Matyas GR, Rao M, Alving CR, Narum DL, Duffy PE. Malaria transmission-blocking conjugate vaccine in ALFQ adjuvant induces durable functional immune responses in rhesus macaques. NPJ Vaccines 2021; 6:148. [PMID: 34887448 PMCID: PMC8660773 DOI: 10.1038/s41541-021-00407-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 11/03/2021] [Indexed: 12/14/2022] Open
Abstract
Malaria transmission-blocking vaccines candidates based on Pfs25 and Pfs230 have advanced to clinical studies. Exoprotein A (EPA) conjugate of Pfs25 in Alhydrogel® developed functional immunity in humans, with limited durability. Pfs230 conjugated to EPA (Pfs230D1-EPA) with liposomal adjuvant AS01 is currently in clinical trials in Mali. Studies with these conjugates revealed that non-human primates are better than mice to recapitulate the human immunogenicity and functional activity. Here, we evaluated the effect of ALFQ, a liposomal adjuvant consisting of TLR4 agonist and QS21, on the immunogenicity of Pfs25-EPA and Pfs230D1-EPA in Rhesus macaques. Both conjugates generated strong antibody responses and functional activity after two vaccinations though activity declined rapidly. A third vaccination of Pfs230D1-EPA induced functional activity lasting at least 9 months. Antibody avidity increased with each vaccination and correlated strongly with functional activity. IgG subclass analysis showed induction of Th1 and Th2 subclass antibody levels that correlated with activity.
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Affiliation(s)
- Puthupparampil V. Scaria
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Charles Anderson
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Olga Muratova
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Nada Alani
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Hung V. Trinh
- grid.507680.c0000 0001 2230 3166U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720A Rockledge Drive, Bethesda, MD 20817 USA
| | - Steven T. Nadakal
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Irfan Zaidi
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Lynn Lambert
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Zoltan Beck
- grid.507680.c0000 0001 2230 3166U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA ,grid.201075.10000 0004 0614 9826Henry M. Jackson Foundation for the Advancement of Military Medicine, 6720A Rockledge Drive, Bethesda, MD 20817 USA ,grid.410513.20000 0000 8800 7493Present Address: Pfizer, Vaccine Research and Development, Pearl River, NY USA
| | - Emma K. Barnafo
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Kelly M. Rausch
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Chris Rowe
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Beth Chen
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Gary R. Matyas
- grid.507680.c0000 0001 2230 3166U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA
| | - Mangala Rao
- grid.507680.c0000 0001 2230 3166U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA
| | - Carl R. Alving
- grid.507680.c0000 0001 2230 3166U.S. Military HIV Research Program, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910 USA
| | - David L. Narum
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
| | - Patrick E. Duffy
- grid.419681.30000 0001 2164 9667Laboratory of Malaria Immunology and Vaccinology, NIAID/NIH, 29 Lincoln Drive, Building 29B, Bethesda, MD 20892-2903 USA
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3
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Rotavirus spike protein ΔVP8* as a novel carrier protein for conjugate vaccine platform with demonstrated antigenic potential for use as bivalent vaccine. Sci Rep 2021; 11:22037. [PMID: 34764353 PMCID: PMC8586335 DOI: 10.1038/s41598-021-01549-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 10/29/2021] [Indexed: 11/18/2022] Open
Abstract
Conjugate vaccine platform is a promising strategy to overcome the poor immunogenicity of bacterial polysaccharide antigens in infants and children. A carrier protein in conjugate vaccines works not only as an immune stimulator to polysaccharide, but also as an immunogen; with the latter generally not considered as a measured outcome in real world. Here, we probed the potential of a conjugate vaccine platform to induce enhanced immunogenicity of a truncated rotavirus spike protein ΔVP8*. ΔVP8* was covalently conjugated to Vi capsular polysaccharide (Vi) of Salmonella Typhi to develop a bivalent vaccine, termed Vi-ΔVP8*. Our results demonstrated that the Vi-ΔVP8* vaccine can induce specific immune responses against both antigens in immunized mice. The conjugate vaccine elicits high antibody titers and functional antibodies against S. Typhi and Rotavirus (RV) when compared to immunization with a single antigen. Together, these results indicate that Vi-ΔVP8* is a potent and immunogenic vaccine candidate, thus strengthening the potential of conjugate vaccine platform with enhanced immune responses to carrier protein, including ΔVP8*.
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Park WJ, Yoon YK, Kim Y, Park JS, Pansuriya R, Cho SN, Seok YJ, Ganapathy R. Development of a bivalent conjugate vaccine candidate against rotaviral diarrhea and tuberculosis using polysaccharide from Mycobacterium tuberculosis conjugated to ΔVP8* protein from rotavirus. Vaccine 2021; 39:6644-6652. [PMID: 34642087 DOI: 10.1016/j.vaccine.2021.09.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 08/20/2021] [Accepted: 09/28/2021] [Indexed: 11/25/2022]
Abstract
Conjugation of carbohydrate antigens with a carrier protein is a clinically proven strategy to overcome the poor immunogenicity of bacterial polysaccharide. In addition to its primary role, which is to help generate a T cell-mediate long-lasting immune response directed against the carbohydrate antigen, the carrier protein in a glycoconjugate vaccine can also play an important role as a protective antigen. Among carrier proteins currently used in licensed conjugate vaccines, non-typeable Haemophilus influenzae protein D has been used as an antigenically active carrier protein. Our previous studies also indicate that some carrier proteins provide B cell epitopes, along with T cell helper epitopes. Herein we investigated the dual role of truncated rotavirus spike protein ΔVP8* as a carrier and a protective antigen. Capsular polysaccharide lipoarabinomannan (LAM), purified from Mycobacterium tuberculosis (M.tb), was chemically conjugated with ΔVP8*. Mouse immunization experiments showed that the resultant conjugates elicited strong and specific immune responses against the polysaccharide antigen, and the responses were comparable to those induced by Diphtheria toxoid (DT)-based conjugates. The conjugate vaccine induced enhanced antibody titers and functional antibodies against ΔVP8* when compared to immunization with the unconjugated ΔVP8*. Thus, these results indicate that ΔVP8* can be a relevant carrier protein for glycoconjugate vaccine and the glycoconjugates consisting of ΔVP8* with LAM are effective bivalent vaccine candidates against rotavirus and tuberculosis.
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Affiliation(s)
- Wook-Jin Park
- School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea; International Vaccine Institute, Seoul 08826, Republic of Korea
| | - Yeon-Kyung Yoon
- International Vaccine Institute, Seoul 08826, Republic of Korea
| | - Youngmi Kim
- College of Medicine and Institute for Immunology and Immunological Diseases, Yonsei University, Seoul 03722, Republic of Korea
| | - Ji-Sun Park
- International Vaccine Institute, Seoul 08826, Republic of Korea
| | | | - Sang-Nae Cho
- College of Medicine and Institute for Immunology and Immunological Diseases, Yonsei University, Seoul 03722, Republic of Korea
| | - Yeong-Jae Seok
- School of Biological Sciences and Institute of Microbiology, Seoul National University, Seoul 08826, Republic of Korea
| | - Ravi Ganapathy
- International Vaccine Institute, Seoul 08826, Republic of Korea.
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5
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Adeagbo BA, Akinlalu AO, Phan T, Guderian J, Boukes G, Willenburg E, Fenner C, Bolaji OO, Fox CB. Controlled Covalent Conjugation of a Tuberculosis Subunit Antigen (ID93) to Liposome Improved In Vitro Th1-Type Cytokine Recall Responses in Human Whole Blood. ACS OMEGA 2020; 5:31306-31313. [PMID: 33324841 PMCID: PMC7726955 DOI: 10.1021/acsomega.0c04774] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Tuberculosis (TB) remains a foremost poverty-related disease with a high rate of mortality despite global immunization with Bacille Calmette-Guérin (BCG). Several adjuvanted recombinant proteins are in clinical development for TB to protect against the disease in infants and adults. Nevertheless, simple mixing of adjuvants with antigens may not be optimal for enhancing the immune response due to poor association. Hence, co-delivery of adjuvants with antigens has been advocated for improved immune response. This report, therefore, presents a strategy of using chemical conjugation to co-deliver an adjuvanted recombinant protein TB vaccine (ID93 + GLA-LSQ). Chemical conjugation involving glutaraldehyde (GA) or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) was used to associate the antigen (ID93) to the modified liposome (mGLA-LSQ). The physicochemical stability of the formulations was evaluated using high-performance liquid chromatography (HPLC) (adjuvant content), dynamic light scattering (DLS, particle size analysis), and sodium dodecyl sulfate-polyacrylamide gel (SDS) electrophoresis (protein analysis). The bioactivity was assessed by cytokine stimulation using fresh whole blood from 10 healthy donors. The conjugates of ID93 + mGLA_LSQ maintained liposomal and protein integrity with the two protein chemistries. The GLA and QS21 content of the vaccine were also stable for 3 months. However, only the glutaraldehyde conjugates provoked significant secretion of interleukin-2 (210.4 ± 11.45 vs 166.7 ± 9.15; p = 0.0059), interferon-gamma (210.5 ± 14.79 vs 144.1 ± 4.997; p = 0.0011), and tumor necrosis factor alpha (2075 ± 46.8 vs 1456 ± 144.8; p = 0.0082) compared to simple mixing. Conjugation of recombinant protein (ID93) to the liposome (mGLA_LSQ) through chemical conjugation resulted in a stable vaccine formulation, which could facilitate co-delivery of the subunit vaccine to promote a robust immune response.
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Affiliation(s)
- Babatunde Ayodeji Adeagbo
- Department
of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, NG 220280, Nigeria
- Infectious
Disease Research Institute, 1616 Eastlake Avenue East Suite 400, Seattle, Washington 98102, United States
| | - Akintunde Oluseto Akinlalu
- Department
of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, NG 220280, Nigeria
| | - Tony Phan
- Infectious
Disease Research Institute, 1616 Eastlake Avenue East Suite 400, Seattle, Washington 98102, United States
| | - Jeff Guderian
- Infectious
Disease Research Institute, 1616 Eastlake Avenue East Suite 400, Seattle, Washington 98102, United States
| | - Gerhardt Boukes
- Afrigen
Biologics (Pty) Limited, South Africa Medical
Research Council Medicina Campus Francie van Zijl Drive, Cape Town, ZA 7500, South Africa
| | - Elize Willenburg
- Afrigen
Biologics (Pty) Limited, South Africa Medical
Research Council Medicina Campus Francie van Zijl Drive, Cape Town, ZA 7500, South Africa
| | - Caryn Fenner
- Afrigen
Biologics (Pty) Limited, South Africa Medical
Research Council Medicina Campus Francie van Zijl Drive, Cape Town, ZA 7500, South Africa
| | - Oluseye Oladotun Bolaji
- Department
of Pharmaceutical Chemistry, Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, NG 220280, Nigeria
| | - Christopher B. Fox
- Infectious
Disease Research Institute, 1616 Eastlake Avenue East Suite 400, Seattle, Washington 98102, United States
- Department
of Global Health, University of Washington, 3980 15th Ave NE, Seattle, Washington 98195, United States
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6
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Scaria PV, Chen BB, Rowe CG, Alani N, Muratova OV, Barnafo EK, Lambert LE, Zaidi IU, Lees A, Rausch KM, Narum DL, Duffy PE. Comparison of carrier proteins to conjugate malaria transmission blocking vaccine antigens, Pfs25 and Pfs230. Vaccine 2020; 38:5480-5489. [PMID: 32600913 PMCID: PMC11127250 DOI: 10.1016/j.vaccine.2020.06.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/18/2022]
Abstract
Malaria transmission blocking vaccines (TBV) target the sexual stage of the parasite and have been pursued as a stand-alone vaccine or for combination with pre-erythrocytic or blood stage vaccines. Our efforts to develop TBV focus primarily on two antigens, Pfs25 and Pfs230. Chemical conjugation of these poorly immunogenic antigens to carrier proteins enhances their immunogenicity, and conjugates of these antigens to Exoprotein A (EPA) are currently under evaluation in clinical trials. Nonetheless, more potent carriers may augment the immunogenicity of these antigens for a more efficacious vaccine; here, we evaluate a series of proteins to identify such a carrier. Pfs25 and Pfs230 were chemically conjugated to 4 different carriers [tetanus toxoid (TT), a recombinant fragment of tetanus toxin heavy chain (rTThc), recombinant CRM197 produced in Pseudomonas fluorescens (CRM197) or in E. coli (EcoCRM®)] and compared to EPA conjugates in mouse immunogenicity studies. Conjugates of each antigen formulated in Alhydrogel® elicited similar antibody titers but showed differences in functional activity. At a 0.5 µg dose, Pfs230 conjugated to TT, CRM197 and EcoCRM® showed significantly higher functional activity compared to EPA. When formulated with the more potent adjuvant GLA-LSQ, all 4 alternate conjugates induced higher antibody titers as well as increased functional activity compared to the EPA conjugate. IgG subclass analysis of Pfs230 conjugates showed no carrier-dependent differences in the IgG profile. While Alhydrogel® formulations induced a Th2 dominant immune response, GLA-LSQ formulations induced a mixed Th1/Th2 response.
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Affiliation(s)
- Puthupparampil V Scaria
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Beth B Chen
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Christopher G Rowe
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Nada Alani
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Olga V Muratova
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Emma K Barnafo
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Lynn E Lambert
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Irfan U Zaidi
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | | | - Kelly M Rausch
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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7
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Outer membrane protein complex as a carrier for malaria transmission blocking antigen Pfs230. NPJ Vaccines 2019; 4:24. [PMID: 31312527 PMCID: PMC6614402 DOI: 10.1038/s41541-019-0121-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 06/07/2019] [Indexed: 12/12/2022] Open
Abstract
Malaria transmission blocking vaccines (TBV) target the mosquito stage of parasite development by passive immunization of mosquitoes feeding on a vaccinated human. Through uptake of vaccine-induced antibodies in a blood meal, mosquito infection is halted and hence transmission to another human host is blocked. Pfs230 is a gametocyte and gamete surface antigen currently under clinical evaluation as a TBV candidate. We have previously shown that chemical conjugation of poorly immunogenic TBV antigens to Exoprotein A (EPA) can enhance their immunogenicity. Here, we assessed Outer Membrane Protein Complex (OMPC), a membrane vesicle derived from Neisseria meningitidis, as a carrier for Pfs230. We prepared Pfs230-OMPC conjugates with varying levels of antigen load and examined immunogenicity in mice. Chemical conjugation of Pfs230 to OMPC enhanced immunogenicity and functional activity of the Pfs230 antigen, and OMPC conjugates achieved 2-fold to 20-fold higher antibody titers than Pfs230-EPA/AdjuPhos® at different doses. OMPC conjugates were highly immunogenic even at low doses, indicating a dose-sparing effect. EPA conjugates induced an IgG subclass profile biased towards a Th2 response, whereas OMPC conjugates induced a strong Th1-biased immune response with high levels of IgG2, which can benefit Pfs230 antibody functional activity, which depends on complement activation. OMPC is a promising carrier for Pfs230 vaccines. Malaria transmission blocking vaccines (TBV) target Plasmodium stages that transmit between human and mosquitos in order to interrupt the parasite’s life cycle and reduce spread. One TBV antigen currently under clinical development is Pf230, which is expressed on sexual Plasmodium stages. In this study, led by Patrick Duffy from the NIAID, researchers improve immunogenicity of Pf230. They chemically conjugate a part of Pf230 to membrane vesicles derived from bacteria, so-called outer membrane protein complexes (OMPC). Immunization of mice with Pf230-OMPC elicits a higher antibody response and a more balanced IgG subclass profile than control immunizations. Serum from Pf230-OMPC-vaccinated mice efficiently blocks infection of mosquitoes. These results with mice encourage further pre-clinical and clinical characterization of OMPC as a carrier for TBV antigens.
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