Immunogenicity and in vitro protective efficacy of a polyepitope Plasmodium falciparum candidate vaccine constructed by epitope shuffling.
A polyepitope chimeric antigen incorporating multiple protective and conservative epitopes from multiple antigens of Plasmodium falciparum has been considered to be more effective in inducing multiple layers of immunity against malaria than a single stage- or single antigen-based vaccine. By modifying the molecular breeding approach to epitope shuffling, we have constructed a polyepitope chimeric gene that encodes 11 B-cell and T-cell proliferative epitope peptides derived from eight key antigens mostly in the blood stage of Plasmodium falciparum. A 35-kDa antigen encoded by this gene, named Malaria RCAg-1, was purified from an E. coli expression system. Immunization of rabbits and mice with the purified protein in the presence of Freund's adjuvant strongly generated long-lasting antibody responses that recognized the corresponding individual epitope peptide in this vaccine as well as blood stage parasites. CD4(+) T-cell responses were also elicited as shown by the enhancement of T-cell proliferation, IFN-gamma and IL-4 level. In vitro assay of protection revealed that vaccine-elicited antibodies could efficiently inhibit the growth of blood-stage parasites. Additionally, the chimeric antigen was recognized by human serum specimens from malaria patients and individuals living in the endemic area. Our studies indicate the potential of M.RCAg-1 recombinant protein as malaria candidate vaccines as well as the rationale of the epitope shuffling technology applied in designing malaria vaccines.
Cai
Qiliang
Q
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing 100005, China.
Peng
Guiying
G
Bu
Lingyi
L
Lin
Yahui
Y
Zhang
Lianhui
L
Lustigmen
Sara
S
Wang
Heng
H
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000917:Antibody Formation / Q000276:immunology; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D049109:Cell Proliferation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000235:genetics / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000378:metabolism; D015847:Interleukin-4 / Q000378:metabolism; D017780:Malaria Vaccines / Q000008:administration & dosage / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology* / Q000648:ultrastructure; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000008:administration & dosage / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D000276:Adjuvants, Immunologic; D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes; D007074:Immunoglobulin G; D017780:Malaria Vaccines; D011993:Recombinant Fusion Proteins; D015847:Interleukin-4; D007371:Interferon-gamma