title: Naturally-acquired cellular immune response against Plasmodium vivax merozoite surface protein-1 paralog antigen.
abstract: BACKGROUND
  Plasmodium vivax merozoite surface protein-1 paralog (PvMSP1P) is a glycosylphosphatidylinositol-anchored protein expressed on the merozoite surface. This molecule is a target of natural immunity, as high anti-MSP1P-19 antibody levels were detected during P. vivax infection and the antibody inhibited PvMSP1P-erythrocyte binding. Recombinant PvMSP1P antigen results in production of a significant Th1 cytokine response in immunized mice. The present study was performed to characterize natural cellular immunity against PvMSP1P-19 and PvDBP region II in acute and recovery P. vivax infection.
  
  
  METHODS
  Peripheral blood mononuclear cells (PBMCs) from acute and recovery P. vivax infection were obtained for lymphocyte proliferation assay upon PvMSP1P-19 and PvDBP region II antigen stimulation. The culture supernatant was examined for the presence of the cytokines IL-2, TNF, IFN-γ and IL-10 by enzyme-linked immunosorbent assay (ELISA). To determine whether Th1 or Th2 have a memory response against PvMSP1P-19 and PvDBPII protein antigen, PBMCs from subjects who had recovered from P. vivax infection 8-10 weeks prior to the study were obtained for lymphocyte proliferation assay. Cytokine-producing cells were analysed by flow cytometry.
  
  
  RESULTS
  IL-2 was detected at high levels in lymphocyte cultures from acutely infected P. vivax patients upon PvMSP1P-19 stimulation. Analysis of the Th1 or Th2 memory response in PBMC cultures from subjects who had recovered from P. vivax infection showed significantly elevated levels of PvMSP1P-19 and PvDBPII-specific IFN-γ-producing cells (P  <  0.05). Interestingly, the response of IFN-γ-producing cells in PvMSP1P stimulation was fourfold greater in recovered subjects than that in acute-infection patients. CD4(+) T cells were the major cell phenotype involved in the response to PvMSP1P-19 and PvDBPII antigen.
  
  
  CONCLUSIONS
  PvMSP1P-19 strongly induces a specific cellular immune response for protection against P. vivax compared with PvDBPII as the antigen induces activation of IFN-γ-producing effector cells following natural P. vivax exposure. Upon stimulation, PvMSP1P-19 has the potential to activate the recall response of Th1 effector memory cells that play a role in killing the parasite.
authors.affiliation: Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand. siriruk.ch@gmail.com.
authors.forename: Siriruk
authors.initials: S
authors.lastname: Changrob
authors.affiliation: Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand. chaniya.lee@mahidol.ac.th.
authors.forename: Chaniya
authors.initials: C
authors.lastname: Leepiyasakulchai
authors.affiliation: Division of Malaria Research Proteo-Science Center, Ehime University, Matsuyama, Ehime, 790-8577, Japan. tsuboi.takafumi.mb@ehime-u.ac.jp.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Tsuboi
authors.affiliation: Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, 200-701, Republic of Korea. chengyang1127@gmail.com.|Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH), Rockville, MD, 20852, USA. chengyang1127@gmail.com.
authors.forename: Yang
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Laboratory Medicine, College of Medicine, Korea University Guro Hospital, 97 Guro Dong Gil, Guro Gu, Seoul, 152-703, Republic of Korea. malarim@korea.ac.kr.
authors.forename: Chae Seung
authors.initials: CS
authors.lastname: Lim
authors.affiliation: Department of Clinical Microbiology and Applied Technology, Faculty of Medical Technology, Mahidol University, Bangkok, Thailand. pchooton@gmail.com.
authors.forename: Patchanee
authors.initials: P
authors.lastname: Chootong
authors.affiliation: Department of Medical Environmental Biology and Tropical Medicine, School of Medicine, Kangwon National University, Chuncheon, Gangwon-do, 200-701, Republic of Korea. ethan@kangwon.ac.kr.
authors.forename: Eun-Taek
authors.initials: ET
authors.lastname: Han
mesh_terms: D000293:Adolescent; D000328:Adult; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D006801:Humans; D016780:Malaria, Vivax / Q000276:immunology*; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D008875:Middle Aged; D010966:Plasmodium vivax / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D055815:Young Adult
chemical_list: D016207:Cytokines; D020066:Merozoite Surface Protein 1