Screening and characterization of antimalarial resistance related genetic structural variations in P. falciparum

• Main Author: Assisi, Christina
• Other Authors: Zbynek Bozdech
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Biological sciences::Genetics; Science::Biological sciences::Molecular biology; Science::Biological sciences::Microbiology::Drug Resistance
• Online Access: https://hdl.handle.net/10356/156357
• Institution: Nanyang Technological University

The emergence of parasite resistance to antimalarials has been impeding the efforts in malaria elimination. Continuous surveillance of treatment failures from the clinical population informs the efficacy of the currently used antimalarial treatment and provide essential clues in deciphering the molecular mechanism of resistance. Screening of resistance biomarkers from clinical isolates has undermined the identification of large genetic variants, mainly due to technical challenges imposed by low quantity of genetic material and low complexity Plasmodium genome, making the analysis prone to bias. This study screened large genetic structural variations from 413 clinical samples collected in Greater Mekong Subregions, the epicentre of antimalarial treatment failures. Samples were obtained in collaboration with Tracking Resistance to Artemisinin Collaboration (TRAC) studies. Large structural variants were screened using an optimized microarray based Comparative Genomic Hybridization (aCGH) technique. We identified Copy Number Amplification in pfmdr1, pfgch1, and pfpm2, previously reported in association with mainly Mefloquine, Sulfadoxine-Pyrimethamine, and Piperaquine resistance, respectively. In addition, we also identified novel CNV in pfvit and pfyhm2 within the same locus, known for function in iron detoxification and mitochondrial electron transport chain, respectively. Four variant genes: pfpm2, pfvit, pfcyp19b, and pfk13, were chosen for biological and phenotypical characterization using an in vitro parasite model. The overall work suggested the CYP19B as a potential downstream effector of K13 C580Y allele as well as PMII and K13 probable compensatory/synergistic relationship in Ring stage; the stage had been shown to exhibit reduced susceptibility to Artemisinin treatment. Collectively, this work presented an additional potential molecular mechanism to the current notion of antimalarial resistance.