Immunoscreening of Plasmodium falciparum proteins expressed in a wheat germ cell-free system reveals a novel malaria vaccine candidate

Sci Rep. 2017 Apr 5;7:46086. doi: 10.1038/srep46086.

Abstract

The number of malaria vaccine candidates in preclinical and clinical development is limited. To identify novel blood-stage malaria vaccine candidates, we constructed a library of 1,827P. falciparum proteins prepared using the wheat germ cell-free system (WGCFS). Also, a high-throughput AlphaScreen procedure was developed to measure antibody reactivity to the recombinant products. Purified IgGs from residents in malaria endemic areas have shown functional activity against blood-stage parasites as judged by an in vitro parasite Growth Inhibition Assay (GIA). Therefore, we evaluated the GIA activity of 51 plasma samples prepared from Malian adults living in a malaria endemic area against the WGCFS library. Using the AlphaScreen-based immunoreactivity measurements, antibody reactivity against 3 proteins was positively associated with GIA activity. Since anti-LSA3-C responses showed the strongest correlation with GIA activity, this protein was investigated further. Anti-LSA3-C-specific antibody purified from Malian adult plasmas showed GIA activity, and expression of LSA3 in blood-stage parasites was confirmed by western blotting. Taken together, we identified LSA3 as a novel blood-stage vaccine candidate, and we propose that this system will be useful for future vaccine candidate discovery.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antibodies, Protozoan / immunology
  • Antibody Formation / immunology
  • Antibody Specificity / immunology
  • Cell-Free System
  • Erythrocytes / parasitology
  • Erythrocytes / ultrastructure
  • Humans
  • Immunoglobulin G / metabolism
  • Malaria Vaccines / immunology*
  • Mali
  • Merozoites / metabolism
  • Merozoites / ultrastructure
  • Parasites / growth & development
  • Plasmodium falciparum / growth & development
  • Plasmodium falciparum / immunology*
  • Plasmodium falciparum / ultrastructure
  • Protozoan Proteins / immunology*
  • Recombinant Proteins / metabolism
  • Triticum / metabolism*

Substances

  • Antibodies, Protozoan
  • Immunoglobulin G
  • Malaria Vaccines
  • Protozoan Proteins
  • Recombinant Proteins