Late-breaking Poster Asia-Pacific Vaccine and Immunotherapy Congress 2024

Fc receptor binding of naturally acquired antibodies to placental binding Plasmodium falciparum infected erythrocytes (#151)

Elizabeth Aitken 1 , Natasha Sharma 1 , Wina Hasang 1 , Kwok Zi Rou 1 , P Mark Hogarth 2 , Bruce Wines 2 , Maria Ome-Kaius 3 , Mwayiwawo Mandanitsa 4 , Victor Mwapasa 5 , Kamija Phiri 5 , Ken Maleta 5 , Feiko ter Kuile 6 , Holger Unger 7 , Stephen Rogerson 1
  1. Department of Infectious Diseases, Peter Doherty Institute, University of Melbourne, Melbourne, Victoria, Asutralia
  2. Burnet Institute, Melbourne, Victoria, Australia
  3. Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
  4. College of Medicine University of Malwi, Malawi
  5. Kamuzu University of Health Sciences, Malawi
  6. Liverpool School of Tropical Medicine, Liverpool
  7. Menzies School of Health Research, Darwin

 Malaria causes significant child and maternal morbidity and mortality. The identification of antibody responses which protect against malaria can assist with vaccine and therapeutic monoclonal antibody design, and antibodies that facilitate uptake or destruction of infected erythrocytes (IEs) by leukocytes or complement-mediated lysis may play important roles. We developed novel assays to measure binding of leukocyte receptors FcγRI, FcγRIIA and FcγRIIIA on IEs after opsonization with plasma from pregnant Papua New Guinean (n=77) and Malawian women (n=40). FcγRI, FcγRIIA and FcγRIIIA binding antibodies to placental binding IEs were acquired in a gravidity-dependent manner (P≤0.063). FcγRI binding antibodies were associated with protection from placental malaria (P=0.02).  FcyRI, IIA and IIIA binding antibody on the IE were weakly to moderately correlated with IgG levels to the IE, and only FcyRI binding antibody on the IE was correlated with FcyRI, IIA or IIIA binding antibodies on recombinant placental binding PfEMP1.  Measuring functional antibodies to IEs provide valuable information on antibody functions and quality in malaria as clinically relevant correlates of protective immunity.