ABSTRACT
Recently, we generated two bacterial recombinant proteins expressing 89 amino acids of the C-terminal domain of the Plasmodium vivax merozoite surface protein-1 and the hexa-histidine tag (His6MSP1(19)). One of these recombinant proteins contained also the amino acid sequence of the universal pan allelic T-cell epitope (His6MSP1(19)-PADRE). In the present study, we evaluated the immunogenic properties of these antigens when administered via the intra-nasal route in the presence of distinct adjuvant formulations. We found that C57BL/6 mice immunized with either recombinant proteins in the presence of the adjuvants cholera toxin (CT) or the Escherichia coli heat labile toxin (LT) developed high and long lasting titers of specific serum antibodies. The induced immune responses reached maximum levels after three immunizing doses with a prevailing IgG1 subclass response. In contrast, mice immunized by intranasal route with His6MSP1(19)-PADRE in the presence of the synthetic oligonucleotides adjuvant CpG ODN 1826 developed lower antibody titers but when combined to CT, CpG addition resulted in enhanced IgG responses characterized by lower IgG1 levels. Considering the limitations of antigens formulations that can be used in humans, mucosal adjuvants can be a reliable alternative for the development of new strategies of immunization using recombinant proteins of P. vivax.
Subject(s)
Humans , Animals , Female , Mice , Immunoglobulin G/immunology , Malaria Vaccines/immunology , Malaria, Vivax/immunology , Merozoite Surface Protein 1/immunology , Plasmodium vivax/immunology , Adjuvants, Immunologic , Administration, Intranasal , Immunity, Cellular/immunology , Immunity, Mucosal/drug effects , Immunoglobulin G/blood , Malaria Vaccines/administration & dosage , Malaria, Vivax/prevention & control , Merozoite Surface Protein 1/administration & dosage , Merozoite Surface Protein 1/genetics , Recombinant Proteins/immunology , Vaccines, Synthetic/immunologyABSTRACT
The thrombospondin related adhesion protein (TRAP) is a malaria pre-erythrocytic antigen currently pursued as malaria vaccine candidate to Plasmodium falciparum. In this study, a long synthetic peptide (LSP) representing a P. vivax TRAP fragment involved in hepatocyte invasion was formulated in both Freund and Montanide ISA 720 adjutants and administered by IM and subcutaneous routes to BALB/c mice and Aotus monkeys. We measured specific humoral immune responses in both animal species and performed a sporozoite challenge in Aotus monkeys to assess the protective efficacy of the vaccine. After immunization both mice and Aotus seroconverted as shown by ELISA, and the specific anti-peptide antibodies cross reacted with the parasite in IFAT assays. Only two out of six immunized animals became infected after P. vivax sporozoite challenge as compared with four out of six animals from the control group. These results suggest that this TRAP fragment has protective potential against P. vivax malaria and deserves further studies as vaccine candidate.
Subject(s)
Animals , Male , Female , Mice , Malaria Vaccines/immunology , Malaria, Vivax/immunology , Plasmodium vivax/immunology , Protozoan Proteins/immunology , Vaccines, Synthetic/immunology , Aotidae , Antibodies, Protozoan/blood , Antibodies, Protozoan/immunology , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique, Indirect , Mice, Inbred BALB C , Malaria Vaccines/administration & dosage , Malaria, Vivax/prevention & control , Pilot Projects , Peptide Fragments/immunology , Vaccines, Synthetic/administration & dosageABSTRACT
El estudio de péptidos antigémicos candidatos al desarrollo de una vacuna contra la malaria por Plasmodium falciparum, ha mostrado la influencia del complejo mayor de histocompatibilidad humano en la respuesta inmune a determinados epítopes parásitarios. El estudio de la asociación entre el Antígeno Leucocitario Humano-B-53 (HLA) y la protección contra malaria severa ha permitido la caracterización de los péptidos presentados por esta molécula definiendo un epítope reconocido por los linfocitos T citotóxicos de los individuos protegidos. A pesar de que existen muchos hallazgos contradictorios, se sugiere la evaluación de este péptido como componente de una vacuna sintética. Otros hallazgos indican que algunas moléculas HLA clase II modifican la respuesta inmune humoral a antígenos parasitarios específicos mostrándose por ejemplo, una asociación positiva entre los portadores del alelo DQw2 y la respuesta de anticuerpos a la secuencia repetitiva (EENV)6 del antígeno Pf155/RESA o una asociación negativa entre los individuos homocigotos al antígeno HLA-DR4 y la respuesta inmune humoral al péptido sintético Spf66. Es importante estudiar los mecanismos por los cuales operan estas asociaciones para definir nuevos péptidos antigénicos potencialmente protectores, verificar el papel de otros genes cuyo locus está ubicado en la región HLA en el desarrollo de susceptibilidad o de resistencia a la infección y aumentar nuestro conocimiento sobre los procesos de selección natural de las moléculas HLA en las poblaciones considerando que el polimorfismo de estas moléculas ha surgido fundamentalmente por el encuentro con diferentes patógenos