Preclinical efficacy and immunogenicity assessment to show that a chimeric Plasmodium falciparum UB05-09 antigen could be a malaria vaccine candidate

Parasite Immunol. 2018 Mar;40(3):e12514. doi: 10.1111/pim.12514. Epub 2018 Jan 25.


Although it is generally agreed that an effective vaccine would greatly accelerate the control of malaria, the lone registered malaria vaccine Mosquirix™ has an efficacy of 30%-60% that wanes rapidly, indicating a need for improved second-generation malaria vaccines. Previous studies suggested that immune responses to a chimeric Plasmodium falciparum antigen UB05-09 are associated with immune protection against malaria. Herein, the preclinical efficacy and immunogenicity of UB05-09 are tested. Growth inhibition assay was employed to measure the effect of anti-UB05-09 antibodies on P. falciparum growth in vitro. BALB/c mice were immunized with UB05-09 and challenged with the lethal Plasmodium yoelii 17XL infection. ELISA was used to measure antigen-specific antibody production. ELISPOT assays were employed to measure interferon-gamma production ex vivo after stimulation with chimeric UB05-09 and its constituent antigens. Purified immunoglobulins raised in rabbits against UB05-09 significantly inhibited P. falciparum growth in vitro compared to that of its respective constituent antigens. A combination of antibodies to UB05-09 and the apical membrane antigen (AMA1) completely inhibited P. falciparum growth in culture. Immunization of BALB/c mice with recombinant UB05-09 blocked parasitaemia and protected them against lethal P. yoelii 17XL challenge infection. These data suggest that UB05-09 is a malaria vaccine candidate that could be developed further and used in conjunction with AMA1 to create a potent malaria vaccine.

Keywords: UB05 antigen; UB05-09; circumsporozoite protein-related antigen; exported protein 1; growth inhibition assay; immunization; malaria vaccine candidate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Protozoan / immunology
  • Antigens, Protozoan / immunology*
  • Disease Models, Animal
  • Female
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / immunology
  • Mice
  • Mice, Inbred BALB C
  • Plasmodium falciparum / immunology
  • Plasmodium yoelii / immunology
  • Protozoan Proteins / immunology*
  • Rabbits


  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Malaria Vaccines
  • Protozoan Proteins

Associated data

  • GENBANK/DQ235690.1
  • GENBANK/XP_001347895