Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

TY - JOUR

T1 - Immunogenicity of a virosomally-formulated Plasmodium falciparum GLURP-MSP3 chimeric protein-based malaria vaccine candidate in comparison to adjuvanted formulations

AU - Tamborrini, Marco

AU - Stoffel, Sabine A

AU - Westerfeld, Nicole

AU - Amacker, Mario

AU - Theisen, Michael

AU - Zurbriggen, Rinaldo

AU - Pluschke, Gerd

PY - 2011

Y1 - 2011

N2 - Background: In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs) have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP. Methods. The highly purified recombinant protein GMZ2 was coupled to phosphatidylethanolamine and the conjugates incorporated into the membrane of IRIVs. The immunogenicity of this adjuvant-free virosomal formulation was compared to GMZ2 formulated with the adjuvants Montanide ISA 720 and Alum in three mouse strains with different genetic backgrounds. Results: Intramuscular injections of all three candidate vaccine formulations induced GMZ2-specific antibody responses in all mice tested. In general, the humoral immune response in outbred NMRI mice was stronger than that in inbred BALB/c and C57BL/6 mice. ELISA with the recombinant antigens demonstrated immunodominance of the GLURP component over the MSP3 component. However, compared to the Al(OH) 3-adjuvanted formulation the two other formulations elicited in NMRI mice a larger proportion of anti-MSP3 antibodies. Analyses of the induced GMZ2-specific IgG subclass profiles showed for all three formulations a predominance of the IgG1 isotype. Immune sera against all three formulations exhibited cross-reactivity with in vitro cultivated blood-stage parasites. Immunofluorescence and immunoblot competition experiments showed that both components of the hybrid protein induced IgG cross-reactive with the corresponding native proteins. Conclusion: A virosomal formulation of the chimeric protein GMZ2 induced P. falciparum blood stage parasite cross-reactive IgG responses specific for both MSP3 and GLURP. GMZ2 thus represents a candidate component suitable for inclusion into a multi-valent virosomal malaria vaccine and influenza virosomes represent a versatile antigen delivery system suitable for adjuvant-free immunization with recombinant proteins.

AB - Background: In clinical trials, immunopotentiating reconstituted influenza virosomes (IRIVs) have shown great potential as a versatile antigen delivery platform for synthetic peptides derived from Plasmodium falciparum antigens. This study describes the immunogenicity of a virosomally-formulated recombinant fusion protein comprising domains of the two malaria vaccine candidate antigens MSP3 and GLURP. Methods. The highly purified recombinant protein GMZ2 was coupled to phosphatidylethanolamine and the conjugates incorporated into the membrane of IRIVs. The immunogenicity of this adjuvant-free virosomal formulation was compared to GMZ2 formulated with the adjuvants Montanide ISA 720 and Alum in three mouse strains with different genetic backgrounds. Results: Intramuscular injections of all three candidate vaccine formulations induced GMZ2-specific antibody responses in all mice tested. In general, the humoral immune response in outbred NMRI mice was stronger than that in inbred BALB/c and C57BL/6 mice. ELISA with the recombinant antigens demonstrated immunodominance of the GLURP component over the MSP3 component. However, compared to the Al(OH) 3-adjuvanted formulation the two other formulations elicited in NMRI mice a larger proportion of anti-MSP3 antibodies. Analyses of the induced GMZ2-specific IgG subclass profiles showed for all three formulations a predominance of the IgG1 isotype. Immune sera against all three formulations exhibited cross-reactivity with in vitro cultivated blood-stage parasites. Immunofluorescence and immunoblot competition experiments showed that both components of the hybrid protein induced IgG cross-reactive with the corresponding native proteins. Conclusion: A virosomal formulation of the chimeric protein GMZ2 induced P. falciparum blood stage parasite cross-reactive IgG responses specific for both MSP3 and GLURP. GMZ2 thus represents a candidate component suitable for inclusion into a multi-valent virosomal malaria vaccine and influenza virosomes represent a versatile antigen delivery system suitable for adjuvant-free immunization with recombinant proteins.

KW - Adjuvants, Immunologic

KW - Animals

KW - Antibodies, Protozoan

KW - Antigens, Protozoan

KW - Cross Reactions

KW - Immunoglobulin G

KW - Injections, Intramuscular

KW - Malaria Vaccines

KW - Mannitol

KW - Mice

KW - Oleic Acids

KW - Plasmodium falciparum

KW - Protozoan Proteins

KW - Recombinant Fusion Proteins

KW - Vaccines, Synthetic

KW - Vaccines, Virosome

U2 - 10.1186/1475-2875-10-359

DO - 10.1186/1475-2875-10-359

M3 - Journal article

C2 - 22166048

SN - 1475-2875

VL - 10

SP - 359

JO - Malaria Journal

JF - Malaria Journal

ER -