Heterologous protection against malaria by a simple chemoattenuated PfSPZ vaccine regimen in a randomized trial

Nat Commun. 2021 May 4;12(1):2518. doi: 10.1038/s41467-021-22740-w.

Abstract

Immunization with Plasmodium falciparum (Pf) sporozoites under chemoprophylaxis (PfSPZ-CVac) is the most efficacious approach to malaria vaccination. Implementation is hampered by a complex chemoprophylaxis regimen and missing evidence for efficacy against heterologous infection. We report the results of a double-blinded, randomized, placebo-controlled trial of a simplified, condensed immunization regimen in malaria-naive volunteers (EudraCT-Nr: 2018-004523-36). Participants are immunized by direct venous inoculation of 1.1 × 105 aseptic, purified, cryopreserved PfSPZ (PfSPZ Challenge) of the PfNF54 strain or normal saline (placebo) on days 1, 6 and 29, with simultaneous oral administration of 10 mg/kg chloroquine base. Primary endpoints are vaccine efficacy tested by controlled human malaria infection (CHMI) using the highly divergent, heterologous strain Pf7G8 and safety. Twelve weeks following immunization, 10/13 participants in the vaccine group are sterilely protected against heterologous CHMI, while (5/5) participants receiving placebo develop parasitemia (risk difference: 77%, p = 0.004, Boschloo's test). Immunization is well tolerated with self-limiting grade 1-2 headaches, pyrexia and fatigue that diminish with each vaccination. Immunization induces 18-fold higher anti-Pf circumsporozoite protein (PfCSP) antibody levels in protected than in unprotected vaccinees (p = 0.028). In addition anti-PfMSP2 antibodies are strongly protection-associated by protein microarray assessment. This PfSPZ-CVac regimen is highly efficacious, simple, safe, well tolerated and highly immunogenic.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antimalarials / therapeutic use
  • Cell Line
  • Chemoprevention
  • Chloroquine / therapeutic use
  • Female
  • Humans
  • Immunoglobulin G / immunology
  • Malaria Vaccines / adverse effects
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / drug therapy
  • Malaria, Falciparum / immunology
  • Malaria, Falciparum / parasitology
  • Malaria, Falciparum / prevention & control*
  • Male
  • Parasitemia / immunology
  • Plasmodium falciparum / immunology*
  • Protein Array Analysis
  • Sporozoites / immunology
  • Vaccination / adverse effects
  • Vaccination / methods*
  • Vaccines, Attenuated / adverse effects
  • Vaccines, Attenuated / immunology*

Substances

  • Antimalarials
  • Immunoglobulin G
  • Malaria Vaccines
  • Vaccines, Attenuated
  • Chloroquine

Associated data

  • EudraCT/2018-004523-36