title: Interferon-γresponses toPlasmodium falciparumvaccine candidate antigens decrease in the absence of malaria transmission.
abstract: BACKGROUND
  Malaria elimination campaigns are planned or active in many countries. The effects of malaria elimination on immune responses such as antigen-specific IFN-γresponses are not well characterized.
  
  
  METHODS
  IFN-γresponses to theP. falciparumantigens circumsporozoite protein, liver stage antigen-1, thrombospondin-related adhesive protein, apical membrane antigen-1, MB2, and merozoite surface protein-1 were tested by ELISA in 243 individuals in highland Kenya in April 2008, October 2008, and April 2009, after a one-year period of interrupted malaria transmission from April 2007 to March 2008.
  
  
  RESULTS
  While one individual (0.4%) tested positive forP. falciparumby PCR inOctober 2008 and another two (0.9%) tested positive in April 2009, no clinical malaria cases were detected during weekly visits. Levels of IFN-γto all antigens decreased significantly from April 2008 to April 2009 (allP< 0.001).
  
  
  CONCLUSIONS
  Naturally acquired IFN-γresponses toP. falciparumantigensare short-lived in the absence of repeatedP. falciparuminfection. Even short periods of malaria interruption may significantly decrease IFN-γresponses toP. falciparumantigens.
authors.affiliation: Department of Zoology, Maseno University, Maseno, Kenya.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Ayieko
authors.affiliation: Department of Biological Sciences, Masai Mara University, Narok, Kenya.
authors.forename: Bilha S
authors.initials: BS
authors.lastname: Ogola
authors.affiliation: Department Biological Sciences, Kabianga University, Kericho, Kenya.
authors.forename: Lyticia
authors.initials: L
authors.lastname: Ochola
authors.affiliation: School of Medicine, Maseno University, Maseno, Kenya.
authors.forename: Gideon A M
authors.initials: GAM
authors.lastname: Ngwena
authors.affiliation: School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Bondo, Kenya.
authors.forename: George
authors.initials: G
authors.lastname: Ayodo
authors.affiliation: School of Public Health, University of Minnesota, Minneapolis, MN, United States.
authors.forename: James S
authors.initials: JS
authors.lastname: Hodges
authors.affiliation: Medical School, University of Minnesota, Minneapolis, MN, United States.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Noland
authors.affiliation: Medical School, Indiana University, Indianapolis, IN, United States.
authors.forename: Chandy C
authors.initials: CC
authors.lastname: John
keywords: Highland Kenya; Interferon gamma; Malaria; Plasmodium falciparum