title: Antibody Profiling in Naïve and Semi-immune Individuals Experimentally Challenged with Plasmodium vivax Sporozoites.
abstract: BACKGROUND
  Acquisition of malaria immunity in low transmission areas usually occurs after relatively few exposures to the parasite. A recent Plasmodium vivax experimental challenge trial in malaria naïve and semi-immune volunteers from Colombia showed that all naïve individuals developed malaria symptoms, whereas semi-immune subjects were asymptomatic or displayed attenuated symptoms. Sera from these individuals were analyzed by protein microarray to identify antibodies associated with clinical protection.
  
  
  RESULTS
  Serum samples from naïve (n = 7) and semi-immune (n = 9) volunteers exposed to P. vivax sporozoite-infected mosquito bites were probed against a custom protein microarray displaying 515 P. vivax antigens. The array revealed higher serological responses in semi-immune individuals before the challenge, although malaria naïve individuals also had pre-existing antibodies, which were higher in Colombians than US adults (control group). In both experimental groups the response to the P. vivax challenge peaked at day 45 and returned to near baseline at day 145. Additional analysis indicated that semi-immune volunteers without fever displayed a lower response to the challenge, but recognized new antigens afterwards.
  
  
  CONCLUSIONS
  Clinical protection against experimental challenge in volunteers with previous P. vivax exposure was associated with elevated pre-existing antibodies, an attenuated serological response to the challenge and reactivity to new antigens.
authors.affiliation: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.|Faculty of Health, Universidad del Valle, Cali, Colombia.
authors.forename: Myriam
authors.initials: M
authors.lastname: Arévalo-Herrera
authors.affiliation: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.|Caucaseco Scientific Research Center, Cali, Colombia.
authors.forename: Mary
authors.initials: M
authors.lastname: Lopez-Perez
authors.affiliation: Department of Medicine, University of California Irvine, Irvine, California, United States of America.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Dotsey
authors.affiliation: Department of Medicine, University of California Irvine, Irvine, California, United States of America.
authors.forename: Aarti
authors.initials: A
authors.lastname: Jain
authors.affiliation: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.
authors.forename: Kelly
authors.initials: K
authors.lastname: Rubiano
authors.affiliation: Department of Medicine, University of California Irvine, Irvine, California, United States of America.
authors.forename: Philip L
authors.initials: PL
authors.lastname: Felgner
authors.affiliation: Department of Medicine, University of California Irvine, Irvine, California, United States of America.
authors.forename: D Huw
authors.initials: DH
authors.lastname: Davies
authors.affiliation: Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia.|Caucaseco Scientific Research Center, Cali, Colombia.
authors.forename: Sócrates
authors.initials: S
authors.lastname: Herrera
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000276:immunology; D000962:Antimalarials / Q000627:therapeutic use; D002738:Chloroquine / Q000627:therapeutic use; D006801:Humans; D016780:Malaria, Vivax / Q000097:blood* / Q000276:immunology; D010966:Plasmodium vivax / Q000276:immunology*; D040081:Protein Array Analysis; D034101:Sporozoites / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000962:Antimalarials; D002738:Chloroquine