Naturally-Acquired Immune Response against Plasmodium vivax Rhoptry-Associated Membrane Antigen

PLoS One. 2016 Feb 17;11(2):e0148723. doi: 10.1371/journal.pone.0148723. eCollection 2016.

Abstract

Rhoptry-associated membrane antigen (RAMA) is an abundant glycophosphatidylinositol (GPI)-anchored protein that is embedded within the lipid bilayer and is implicated in parasite invasion. Antibody responses against rhoptry proteins are produced by individuals living in a malaria-endemic area, suggesting the immunogenicity of Plasmodium vivax RAMA (PvRAMA) for induction of immune responses during P. vivax infection. To determine whether PvRAMA contributes to the acquisition of immunity to malaria and could be a rational candidate for a vaccine, the presence of memory T cells and the stability of the antibody response against PvRAMA were evaluated in P. vivax-exposed individuals. The immunogenicity of PvRAMA for the induction of T cell responses was evaluated by in vitro stimulation of peripheral blood mononuclear cells (PBMCs). High levels of interferon (IFN)-γ and interleukin (IL)-10 cytokines were detected in the culture supernatant of PBMCs, and the CD4+ T cells predominantly produced IL-10 cytokine. The levels of total anti-PvRAMA immunoglobulin G (IgG) antibody were significantly elevated, and these antibodies persisted over the 12 months of the study. Interestingly, IgG1, IgG2 and IgG3 were the major antibody subtypes in the response to PvRAMA. The frequency of IgG3 in specific to PvRAMA antigen maintained over 12 months. These data could explain the immunogenicity of PvRAMA antigen in induction of both cell-mediated and antibody-mediated immunity in natural P. vivax infection, in which IFN-γ helps antibody class switching toward the IgG1, IgG2 and IgG3 isotypes and IL-10 supports PvRAMA-specific antibody production.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptive Immunity / immunology*
  • Adolescent
  • Adult
  • Antibodies, Protozoan / immunology
  • Antibody Formation / immunology
  • CD4-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / immunology
  • Female
  • Flow Cytometry
  • Humans
  • Immunoglobulin G / immunology
  • Interferon-gamma / metabolism
  • Interleukin-10 / metabolism
  • Male
  • Middle Aged
  • Plasmodium vivax / immunology*
  • Protein Stability
  • Protozoan Proteins / immunology*
  • Young Adult

Substances

  • Antibodies, Protozoan
  • Immunoglobulin G
  • Protozoan Proteins
  • rhoptry associated protein, Plasmodium
  • Interleukin-10
  • Interferon-gamma

Grants and funding

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. NRF-2014R1A2A1A11052079) and a grant from the Korea Health Technology R&D Project, the Ministry of Health & Welfare, Republic of Korea (A121180). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.