scholarly journals A Bicistronic DNA Vaccine Containing Apical Membrane Antigen 1 and Merozoite Surface Protein 4/5 Can Prime Humoral and Cellular Immune Responses and Partially Protect Mice against Virulent Plasmodium chabaudi adami DS Malaria

2004 ◽  
Vol 72 (10) ◽  
pp. 5565-5573 ◽  
Author(s):  
A. Rainczuk ◽  
T. Scorza ◽  
T. W. Spithill ◽  
P. M. Smooker
Keyword(s):  
Immune Responses ◽  
Dna Vaccine ◽  
Apical Membrane ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Delivery Systems ◽  
Plasmodium Chabaudi ◽  
Apical Membrane Antigen 1 ◽  
Apical Membrane Antigen

ABSTRACT The ultimate malaria vaccine will require the delivery of multiple antigens from different stages of the complex malaria life cycle. In order to efficiently deliver multiple antigens with use of DNA vaccine technology, new antigen delivery systems must be assessed. This study utilized a bicistronic vector construct, containing an internal ribosome entry site, expressing a combination of malarial candidate antigens: merozoite surface protein 4/5 (MSP4/5) (fused to a monocyte chemotactic protein 3 chemoattractant sequence) and apical membrane antigen 1 (AMA-1) (fused to a tissue plasminogen activator secretion signal). Transfection of COS 7 cells with bicistronic plasmids resulted in production and secretion of both AMA-1 and MSP4/5 in vitro. Vaccination of BALB/c mice via intraepidermal gene gun and intramuscular routes against AMA-1 and MSP4/5 resulted in antibody production and significant in vitro proliferation of splenocytes stimulated by both AMA-1 and MSP4/5. Survival of BALB/c mice vaccinated with bicistronic constructs after lethal Plasmodium chabaudi adami DS erythrocytic-stage challenge was variable, although significant increases in survival and reductions in peak parasitemia were observed in several challenge trials when the vaccine was delivered by the intramuscular route. This study using a murine model demonstrates that the delivery of malarial antigens via bicistronic vectors is feasible. Further experimentation with bicistronic delivery systems is required for the optimization and refinement of DNA vaccines to effectively prime protective immune responses against malaria.

scholarly journals Prediction of Merozoite Surface Protein 1 and Apical Membrane Antigen 1 Vaccine Efficacies against Plasmodium chabaudi Malaria Based on Prechallenge Antibody Responses

2008 ◽  
Vol 16 (3) ◽  
pp. 293-302 ◽  
Author(s):  
Michelle M. Lynch ◽  
Amy Cernetich-Ott ◽  
William P. Weidanz ◽  
James M. Burns
Keyword(s):  
Apical Membrane ◽  
Protective Efficacy ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Antibody Responses ◽  
Enzyme Linked Immunosorbent Assay ◽  
Plasmodium Chabaudi ◽  
Apical Membrane Antigen 1 ◽  
Merozoite Surface Protein 1 ◽  
Apical Membrane Antigen

ABSTRACT For the development of blood-stage malaria vaccines, there is a clear need to establish in vitro measures of the antibody-mediated and the cell-mediated immune responses that correlate with protection. In this study, we focused on establishing correlates of antibody-mediated immunity induced by immunization with apical membrane antigen 1 (AMA1) and merozoite surface protein 142 (MSP142) subunit vaccines. To do so, we exploited the Plasmodium chabaudi rodent model, with which we can immunize animals with both protective and nonprotective vaccine formulations and allow the parasitemia in the challenged animals to peak. Vaccine formulations were varied with regard to the antigen dose, the antigen conformation, and the adjuvant used. Prechallenge antibody responses were evaluated by enzyme-linked immunosorbent assay and were tested for a correlation with protection against nonlethal P. chabaudi malaria, as measured by a reduction in the peak level of parasitemia. The analysis showed that neither the isotype profile nor the avidity of vaccine-induced antibodies correlated with protective efficacy. However, high titers of antibodies directed against conformation-independent epitopes were associated with poor vaccine performance and may limit the effectiveness of protective antibodies that recognize conformation-dependent epitopes. We were able to predict the efficacies of the P. chabaudi AMA1 (PcAMA1) and P. chabaudi MSP142 (PcMSP142) vaccines only when the prechallenge antibody titers to both refolded and reduced/alkylated antigens were considered in combination. The relative importance of these two measures of vaccine-induced responses as predictors of protection differed somewhat for the PcAMA1 and the PcMSP142 vaccines, a finding confirmed in our final immunization and challenge study. A similar approach to the evaluation of vaccine-induced antibody responses may be useful during clinical trials of Plasmodium falciparum AMA1 and MSP142 vaccines.

scholarly journals Protection against Plasmodium chabaudi Malaria Induced by Immunization with Apical Membrane Antigen 1 and Merozoite Surface Protein 1 in the Absence of Gamma Interferon or Interleukin-4

2004 ◽  
Vol 72 (10) ◽  
pp. 5605-5612 ◽  
Author(s):  
James M. Burns ◽  
Patrick R. Flaherty ◽  
Payal Nanavati ◽  
William P. Weidanz
Keyword(s):  
Apical Membrane ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Gamma Interferon ◽  
Interleukin 4 ◽  
Plasmodium Chabaudi ◽  
Protective Antibody ◽  
Apical Membrane Antigen 1 ◽  
Immune Mechanisms ◽  
Merozoite Surface Protein 1

ABSTRACT Strategies to optimize formulations of multisubunit malaria vaccines require a basic knowledge of underlying protective immune mechanisms induced by each vaccine component. In the present study, we evaluated the contribution of antibody-mediated and cell-mediated immune mechanisms to the protection induced by immunization with two blood-stage malaria vaccine candidate antigens, apical membrane antigen 1 (AMA-1) and merozoite surface protein 1 (MSP-1). Immunologically intact or selected immunologic knockout mice were immunized with purified recombinant Plasmodium chabaudi AMA-1 (PcAMA-1) and/or the 42-kDa C-terminal processing fragment of P. chabaudi MSP-1 (MSP-142). The efficacy of immunization in each animal model was measured as protection against blood-stage P. chabaudi malaria. Immunization of B-cell-deficient JH −/− mice indicated that PcAMA-1 vaccine-induced immunity is largely antibody dependent. In contrast, JH −/− mice immunized with PcMSP-142 were partially protected against P. chabaudi malaria, indicating a role for protective antibody-dependent and antibody-independent mechanisms of immunity. The involvement of γδ T cells in vaccine-induced PcAMA-1 and/or PcMSP-142 protection was minor. Analysis of the isotypic profile of antigen-specific antibodies induced by immunization of immunologically intact mice revealed a dominant IgG1 response. However, neither interleukin-4 and the production of IgG1 antibodies nor gamma interferon and the production of IgG2a/c antibodies were essential for PcAMA-1 and/or PcMSP-142 vaccine-induced protection. Therefore, for protective antibody-mediated immunity, vaccine adjuvants and delivery systems for AMA-1- and MSP-1-based vaccines can be selected for their ability to maximize responses irrespective of IgG isotype or any Th1 versus Th2 bias in the CD4+-T-cell response.

scholarly journals Anti-Apical-Membrane-Antigen-1 Antibody Is More Effective than Anti-42-Kilodalton-Merozoite-Surface-Protein-1 Antibody in Inhibiting Plasmodium falciparum Growth, as Determined by the In Vitro Growth Inhibition Assay

2009 ◽  
Vol 16 (7) ◽  
pp. 963-968 ◽  
Author(s):  
Kazutoyo Miura ◽  
Hong Zhou ◽  
Ababacar Diouf ◽  
Samuel E. Moretz ◽  
Michael P. Fay ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Surface Protein ◽  
Merozoite Surface Protein ◽  
Inhibition Assay ◽  
Growth Inhibition Assay ◽  
Apical Membrane Antigen 1 ◽  
Merozoite Surface Protein 1 ◽  
Growth Inhibitory ◽  
Growth Inhibitory Activity

ABSTRACT Apical membrane antigen 1 (AMA1) and the 42-kDa merozoite surface protein 1 (MSP142) are leading malaria vaccine candidates. Several preclinical and clinical trials have been conducted, and an in vitro parasite growth inhibition assay has been used to evaluate the biological activities of the resulting antibodies. In a U.S. phase 1 trial with AMA1-C1/Alhydrogel plus CPG 7909, the vaccination elicited anti-AMA1 immunoglobulin G (IgG) which showed up to 96% inhibition. However, antibodies induced by MSP142-C1/Alhydrogel plus CPG 7909 vaccine showed less than 32% inhibition in vitro. To determine whether anti-MSP142 IgG had less growth-inhibitory activity than anti-AMA1 IgG in vitro, the amounts of IgG that produced 50% inhibition of parasite growth (Ab50) were compared for rabbit and human antibodies. The Ab50s of rabbit and human anti-MSP142 IgGs were significantly higher (0.21 and 0.62 mg/ml, respectively) than those of anti-AMA1 IgGs (0.07 and 0.10 mg/ml, respectively) against 3D7 parasites. Ab50 data against FVO parasites also demonstrated significant differences. We further investigated the Ab50s of mouse and monkey anti-AMA1 IgGs and showed that there were significant differences between the species (mouse, 0.28 mg/ml, and monkey, 0.14 mg/ml, against 3D7 parasites). Although it is unknown whether growth-inhibitory activity in vitro reflects protective immunity in vivo, this study showed that the Ab50 varies with both antigen and species. Our data provide a benchmark for antibody levels for future AMA1- or MSP142-based vaccine development efforts in preclinical and clinical trials.

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