Rapid Fire Presentation 8th International Conference on Plasmodium vivax Research 2022

A fluorometric assay to determine the protective effect of Glucose-6-Phosphate Dehydrogenase (G6PD) against a Plasmodium spp. infection in females heterozygous for the G6PD gene: Proof of concept in Plasmodium falciparum (#331)

Angela AR Rumaseb 1 , Jutta JM Marfurt 1 , Steven SK Kho 1 , Maria MK Kahn 2 , Ric RNP Price 1 3 4 , Benedikt BL Ley 1
  1. Global and Tropical Health Division, Menzies School of Health Research, Darwin, NT, Australia
  2. PATH Diagnostics Group, Seattle, Washington, United States of America
  3. Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, UK
  4. Mahidol‐Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand

OBJECTIVE

Glucose-6-phosphate dehydrogenase (G6PD) deficiency offers some protection against malaria; however, the degree of protection is poorly described and likely to vary with G6PD genotype and Plasmodium species. We present a novel approach to quantify the differential invasion rates of P. falciparum between G6PD deficient and normal red blood cells (RBCs) in an ex vivo model.

A flow-cytometry based assay was developed to distinguish G6PD deficient and normal, parasitized and non-parasitized RBCs within the same sample. Venous blood collected from a G6PD heterozygous female was infected and cultured ex vivo with a laboratory strain of P. falciparum (FC27).

RESULTS

Aliquots of infected blood were assayed at schizont and subsequent synchronized ring stages. At schizont stage, 84.9% of RBCs were G6PD deficient of which 0.4% were parasitized compared to 2.0% of normal RBCs. In the subsequent ring stage, 90.4% of RBCs were deficient and 0.2% of deficient and 0.9% of normal cells respectively were parasitized. The pooled Odds Ratio for a deficient RBC to be parasitized was 0.2 (95% confidence interval: 0.18 – 0.22, p<0.001) compared to a normal cell. Further studies are warranted to explore preferential parasitisation with different G6PD variants and Plasmodium species.