Vaccine-induced monoclonal antibodies targeting circumsporozoite protein prevent Plasmodium falciparum infection

J Clin Invest. 2014 Jan;124(1):140-4. doi: 10.1172/JCI70349.

Abstract

Malaria, which is the result of Plasmodium falciparum infection, is a global health threat that resulted in 655,000 deaths and 216 million clinical cases in 2010 alone. Recent phase 3 trials with malaria vaccine candidate RTS,S/AS01 (RTS,S) in children has demonstrated modest efficacy against clinical and severe malaria. RTS,S targets the pre-erythrocytic phase of the disease and induces high antibody titers against the P. falciparum circumsporozoite protein (CSP) and a moderate CD4(+) T cell response. The individual contribution of these adaptive immune responses to protection from infection remains unknown. Here, we found that prophylactic administration of anti-CSP mAbs derived from an RTS,S-vaccinated recipient fully protected mice with humanized livers from i.v.- and mosquito bite–delivered P. falciparum sporozoite challenge. Titers of anti-CSP that conveyed full protection were within the range observed in human RTS,S vaccine recipients. Increasing anti-CSP titers resulted in a dose-dependent reduction of the liver parasite burden. These data indicate that RTS,S-induced antibodies are protective and provide sterilizing immunity against P. falciparum infection when reaching or exceeding a critical plasma concentration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology*
  • Clinical Trials as Topic
  • Humans
  • Liver / parasitology
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / prevention & control*
  • Mice
  • Mice, SCID
  • Plasmodium falciparum / immunology*
  • Protozoan Proteins / immunology*
  • Sporozoites / immunology
  • Vaccination
  • Vaccines, Synthetic / immunology*

Substances

  • Antibodies, Monoclonal
  • Malaria Vaccines
  • Protozoan Proteins
  • RTS,S-AS01 vaccine
  • Vaccines, Synthetic
  • circumsporozoite protein, Protozoan